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Cathodic processes in initial stages of atmospheric corrosion of rolled zinc and bare, Al–Si and Zn–Fe coated press hardened steel were studied. A ratio between hydrogen evolution and oxygen reduction reactions was evaluated using the manometric respirometry technique. Hydrogen evolution reaction proceeded on all studied materials, providing from 7 to 27 % of the cathodic current. The content of diffusible hydrogen in steel was low indicating that hydrogen recombination was highly efficient and only a minor part of produced hydrogen absorbed into the materials. The efficiency of hydrogen recombination is thus expected to control the hydrogen entry process. • Respirometry is suitable for studies of cathodic processes in atmospheric corrosion. • Hydrogen evolution reaction proceeded on all studied materials. • Only low amounts of diffusible hydrogen found in steel structure. • Hydrogen recombination is significantly more efficient compared to absorption. • Hydrogen formation on zinc enhanced in CO 2 -free atmosphere. [ABSTRACT FROM AUTHOR]

Due to its high use, amoxicillin (AMX) contributes in a large measure to the pollution of aquatic environment. Unfortunately this emerging pollutant has not been covered by the release standards. There is little information regarding the AMX effect on heterotrophic biomass of the wastewater treatment plant (WWTP), which are not designed to degrade them, causing possible dysfunction. The novelty in this study is the application of LFS respirometer as a fast, efficient and robust means to evaluate the AMX effect on heterotrophs response, allowing the determination of inhibition rates by simulating the biological processes taking place in conventional WWTP. Three types of activated sludge and an easily biodegradable synthetic substrate based on sodium acetate at 300 mgCOD/L considering the ratio S0/X0 = 0.04 gCOD/gVSS, were used. Respirometry showed quite different and low inhibition rates of heterotrophic where the maximum reduction in YO/S rate was 30.6%, 22% and 20% for 75, 120 and 150 mgAMX/L, respectively explaining that the heterotrophic biomass adapted to the substrate and to AMX showed a fairly significant resistance to inhibition compared to non-acclimated one. Heterotrophs biomasses are less sensitive and quick to adapt because they were inhibited by 35% at 150 mgAMX/L, on other, biomass contained autotrophes, which were inhibited up to 35% in 25 mgAMX/L. [ABSTRACT FROM AUTHOR]

Bioturbation in estuarine environments describes all sediment reworking processes implied in sediment transport. However, modelling at large spatial and temporal scales remains a challenge because of the need to consider the fauna at the community level, and because animal behaviour is highly seasonal with non-linear effects of macrofauna functional trait interactions. Bioturbation processes can be linked to the activity of organisms, based on the principle of energy ecology, linking the metabolic rate to the erodibility of a sediment colonised by benthic fauna. This study investigates this postulate by evaluating the erodibility parameters of a sediment subjected to: i) the bioturbation under seasonal temperature variations; ii) the synergistic bioturbation of different species. The experimental design consisted of: i) three temperature levels (winter, spring and summer), ii) three types of species duos (Cerastoderma edule and Macoma balthica ; Scrobicularia plana and Hediste diversicolor ; Corophium volutator and Peringia ulvae) at 4 different relative densities. Two successive experiments were carried out on the same individuals: measurement of oxygen consumption of fauna then measurement of the erodibility of the colonised sediment in a flume. The oxygen consumption confirmed that the metabolic rate is a good model of the fauna respiration, regardless of species. The erosion results indicated that the metabolic rate in the case of the fluff layer resuspension is an interesting descriptor for 1) the assessment of the bioturbation under variable temperatures and 2) the integration of the two different bioturbator species that could co-occur in the same habitat. In contrast, the effect of bioturbation on the mass sediment erosion threshold cannot be easily modelled by using the metabolic rate and the classification in functional groups is required. Bioturbation models of the fluff layer using metabolic rate is a promising tool for modelling the effects of faunal communities on sediment transport at the scale of an estuary and over the long term, even projected in the context of global warming. [Display omitted] • Temperature influences the effect of bioturbation on sediment erodibility by regulating physiological metabolism. • The erosion of the fluff layer is positively linked to the total metabolic rate, without consideration of the species. • The mass sediment erosion threshold is negatively impacted by some species, without consideration of their metabolic rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Clark electrode gives reliable O 2 results for metabolic rate calculation in ants. • Ant castes (queens and workers) have different allometric coefficient. Respirometry provides a direct measure of an organism's O 2 consumption rate (VO 2), which is a significant component of its metabolic rate (energy expenditure). Amongst ants, variations in lifespan between different social castes (such as workers and queens) can be substantial, varying depending on the species. As metabolic rate is higher in short-living species, we aimed to determine how VO 2 and longevity may have coevolved within ant casts. Measuring VO 2 in such tiny animal models can be challenging, and as a first methodological step, we validate the use of a Clark electrode, initially designed for measuring mitochondrial respiration control pathways, for assessing VO 2 in ants within a sealed chamber. This was done by comparing it with stop-flow VO 2 and CO 2 production, using a traditional indirect calorimetry device. The global aim is to provide a reliable protocol to conduct accurate comparisons of metabolic rates within and among ant species. As expected, using the Clark electrode entails high time resolution and revealed that queens and workers exhibited discontinuous gas exchange, with episodes of apnea lasting up to 20 min. [ABSTRACT FROM AUTHOR]

There is a dearth of basic life history and physiological data from Southern Ocean species, particularly from benthic vagile predators. This is an important data gap because species inhabiting the Southern Ocean live in a more temperature stable but seasonally varying environment than temperate and tropical counterparts. For many species living below 0 °C for a significant proportion of the year, bodily functions are slowed to disproportionately lower rates than would be predicted by temperature alone. Certain life history and physiological processes are often aligned with the short summer season of productivity. However, predators may behave differently because they are decoupled from the phytoplankton bloom and some have been shown to exhibit less seasonal physiological change. To further our understanding of Antarctic predator growth and seasonal ecophysiology, field growth rates were measured for two soft-bodied Antarctic anemone benthic predators, Isotealia antarctica and Urticinopsis antarctica, using in situ sampling of anemones on uniquely marked tiles. Ex situ measurements of oxygen consumption and seven-day faecal output were obtained from recently collected specimens in aquaria and compared between summer and winter. Winter physiological data for Antarctic species are rare, and we tested the hypothesis that generalist feeders or predators continue to feed during the winter. Growth rates differed between species and between years. I. antarctica and U. antarctica both exhibited overall positive field growth rates across a 15 month period between 2020 and 2021; with U. antarctica increasing 199.80% (± SE 25.8) in mass compared to a 16.85% (± SE 8.9) increase in I. antarctica. There was no significant difference in I. antarctica ' s growth between 15 and 25 months field deployment. After 25 months, I. antarctica showed an average 7.96% (± SE 8.05) increase in buoyant weight. Ex situ oxygen consumption and faecal egestion did not differ seasonally, which, demonstrates that anemones fed at similar rates during the winter and summer. In contrast to some members of the Antarctica benthos, I. antarctica and U. antarctica actively feed all year round, whereas several other species have been reported to enter a state of torpor in winter. • Field growth rates show species-specific differences in growth. • Urticinopsis antarctica grew 183% faster than Isotealia antarctica across a 15-month growth period. • There was no seasonal difference in faecal egestion for either anemone species. • Both anemones exhibit similar metabolic rates during summer and winter. • We demonstrate year-round feeding in I. antarctica and U. antarctica. [ABSTRACT FROM AUTHOR]

Nitrite has been viewed essentially as an inert metabolic endpoint of nitric oxide (•NO). However, under certain conditions, nitrite can be a source of •NO. In the brain, this alternative source of •NO production independent of nitric oxide synthase activity may be particularly relevant in ischemia/reperfusion (I/R), where low oxygen availability limits enzymatic production of •NO. Notably, in vivo concentration of nitrite can be easily increased with diet, through the ingestion of nitrate-rich foods, opening the window for a therapeutic intervention based on diet. Considering the modulation of mitochondrial respiration by •NO, we have hypothesized that the protective action of nitrite in I/R may also result from modulation of mitochondrial function. We used high-resolution respirometry to evaluate the effects of nitrite in two in vitro models of I/R. In both cases, an increase in oxygen flux was observed following reoxygenation, a phenomenon that has been coined "oxidative burst". The amplitude of this "oxidative burst" was decreased by nitrite in a concentration-dependent manner. Additionally, a pilot in vivo study in which animals received a nitrate-rich diet as a strategy to increase circulating and tissue levels of nitrite also revealed that the "oxidative burst" was decreased in the nitrate-treated animals. These results may provide mechanistic support to the observation of a protective effect of nitrite in situations of brain ischemia. [Display omitted] • Ischemia/Reperfusion in hippocampal slices reveals oxidative burst upon reperfusion at the tissue level; • Nitrite reduces oxidative burst upon reperfusion in hippocampal slices; • In vivo nitrate supplementation reduces oxidative burst upon reperfusion in hippocampal slices. [ABSTRACT FROM AUTHOR]

Chemical disinfection in a recirculating aquaculture system (RAS) may affect biofilm-associated bacteria and the nitrification performance in the biofilter units. The biofilm response to chemical disinfectants in RAS remains unclear, but it can be understood using methods to quantify biofilm activity. Here, we compared the effects of two disinfection strategies, continuous ozone at 0.06 mg/L Cl 2 equivalent (Ozone group) and peracetic acid (PAA) at 1 mg/L (PAA group) to control group without disinfectant, on biofilm activity on biofilter elements from nine identical experimental RAS with Atlantic salmon parr (Salmo salar) during a four-week trial. Biofilm activities on biofilter elements from the three groups were examined by measuring oxygen consumption rates (OCR) following sequential spiking with pure tap water, and tap water spiked with nitrite or ammonium, as well as oxygen release rate (k or) following hydrogen peroxide (H 2 O 2) addition, to estimate metabolic activities of biofilm related to endogenous respiration and substrate turnover. The results show that the applied PAA dose increased the endogenous respiration activity of biofilm by 39–133%, stimulated the rate of biofilm enzymatic decomposition of H 2 O 2 by 135%, and partially impaired the biofilm metabolism for nitrite oxidation (decrease by 36%), resulting in a significant nitrite accumulation (rise by 59%) in the cultured water, compared to control over experimental period. Ozone treatment caused an enhanced endogenous respiration activity of biofilm at the beginning of the experiment (increase by 45–74%), but dropped to control levels at the end of the experiment. The results indicate that chronic exposure to PAA can alter the metabolic state of biofilm, which can have consequences for biofilter functions, while chronic exposure to ozone improved water clarity without compromising the metabolic status of biofilm. The investigations provided insights into biofilm response to chemical disinfectant in RAS, which would benefit the optimization of an effective and safe use of disinfectants in RAS. • Respirometry was applied to estimate biofilm activity within RAS biofilters. • Impacts of ozone and PAA disinfection on biofilm activity were assessed. • PAA altered biofilm metabolic state with consequences for the intended function. • Ozone applied improved water clarity without compromising biofilm metabolic status. [ABSTRACT FROM AUTHOR]

Glucose is the main energy source of the brain, yet recent studies demonstrate that fatty acid oxidation (FAO) plays a relevant role in the pathogenesis of central nervous system disorders. We evaluated FAO in brain mitochondria under physiological conditions, in the aging brain, and after stroke. Using high-resolution respirometry we compared medium-chain (MC, octanoylcarnitine) and long-chain (LC, palmitoylcarnitine) acylcarnitines as substrates of β-oxidation in the brain. The protocols developed avoid FAO overestimation by malate-linked anaplerotic activity in brain mitochondria. The capacity of FA oxidative phosphorylation (F-OXPHOS) with palmitoylcarnitine was up to 4 times higher than respiration with octanoylcarnitine. The optimal concentration of palmitoylcarnitine was 10 μM which corresponds to the total concentration of LC acylcarnitines in the brain. Maximal respiration with octanoylcarnitine was reached at 20 μM, however, this concentration exceeds MC acylcarnitine concentrations in the brain 15 times. F-OXPHOS capacity was highest in mouse cerebellum, intermediate in cortex, prefrontal cortex, and hypothalamus, and hardly detectable in hippocampus. F-OXPHOS capacity was 2-fold lower and concentrations of LC acylcarnitines were 2-fold higher in brain of aged rats. A similar trend was observed in the rat model of endothelin-1-induced stroke, but reduction of OXPHOS capacity was not limited to FAO. In conclusion, although FAO is not a dominant pathway in brain bioenergetics, it deserves specific attention in studies of brain metabolism. • Fatty acid oxidation analysis by high-resolution respirometry avoiding artefacts. • Fatty acid oxidation-linked respiration was compared in mice, rats, and fly brains. • In rat brains, fatty acid-linked respiration decreased specifically with age. • Acylcarnitine accumulated in brain associated with fatty acid oxidation decline. • Fatty acid oxidation is low in brain energy metabolism but deserves attention. [ABSTRACT FROM AUTHOR]

An organism's oxygen supply capacity, measured as a ratio of a metabolic rate to its critical oxygen partial pressure, describes the efficacy of oxygen uptake and transport. This metric is sensitive to errors in oxygen measurement, especially near anoxia where the magnitude of instrument error as a proportion of total signal is magnified. Here, we present a conceptual and mathematical method that uses this sensitivity to identify, quantify, and therefore correct oxygen measurements collected using inaccurately calibrated sensors. When appropriate, adding a small correction value to each oxygen measurement counteracts the effects of this error and provides results that are comparable to data from accurately calibrated oxygen probes. We demonstrate, using simulated, laboratory, and literature datasets, how this method can be used post hoc to diagnose error in, correct the magnitude of, and reduce the variability in repeat measures of traits relevant to oxygen tolerance. [Display omitted] • Errors in oxygen measurement can bias estimates of the oxygen supply capacity. • Using physiological principles, we can correct for this error. • Corrected oxygen observations are comparable to data collected without error. [ABSTRACT FROM AUTHOR]

Yellowtail kingfish (Seriola lalandi) are a highly active marine species, with increasing value in commercial aquaculture. While practices which manipulate oxygen (O 2) dynamics through metabolic demand and environmental O 2 supply have been shown to impact juvenile growth rate in fish development, there has been no work exploring the effects of O 2 at the subcellular level. In addition, manipulation of O 2 supply or demand via changes in environmental factors such as O 2 levels or salinity, may impact whole animal performance. Still, there has been little work exploring the physiological effects at a subcellular level. Mitochondria (mt) consume O 2 and are pivotal in central metabolism, directly impacting growth, and dictating whole animal performance. Here we explore the effects of manipulating O 2 demand and supply on mt in yellowtail kingfish ventricle and skeletal muscle by exposure to chronic hyperoxia (200% [O 2 ], 35 ppt) and to hypoosmotic conditions (100% [O 2 ], 17.5 ppt). Chronic exposure to hypoosmotic conditions resulted in greater overall biomass, while it lowered relative ventricular mass compared to control fish. Mitochondrial respiratory flux for most measures remained consistent with control fish, with the exception of cytochrome c oxidase (COX) respiration. Chronic hyperoxia had no impact on overall morphology, and no significant effect on ventricle mt respiration, yet increased COX activity in skeletal muscle. These data indicate that lowering routine mt O 2 demands in S. lalandi with hypoosmotic conditions has more impact than increasing O 2 availability, and that this may enhance biomass output while maintaining mt integrity. • Decreasing routine oxygen demands of S. lalandi (Yellow tailed Kingfish) during rearing through lowering environmental salinity, showed increased benefits on both whole organism overall biomass and mitochondrial function in skeletal and cardiac muscle, while manipulation of oxygen supply (i.e. chronic hyperoxia) showed no impact on S. lalandi morphology, and only elevated oxygen flux at cytochrome c oxidase in skeletal muscle mitochondria. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of Paraná Basin basalt powder, a mining byproduct from southern Brazil, on the macro- and micronutrient content of two soil types, Oxisol (OX) and Typic Quartzipsamment (TQ), as well as the metabolic activity of soil microorganisms. Basalt powder doses were determined based on CaO levels required to correct Ca2+ levels in each soil, ranging from 0 to 4 times the recommended amount. Soil samples were collected for analysis after 60 and 170 days of incubation to assess soil attributes. Additionally, a laboratory study examined soil basal respiration (SBR) after 168 days of greenhouse incubation. The results revealed that higher doses of basalt powder application led to increased pH, P, K+, Ca2+, Mg2+, Cu, B, and Si levels in OX, while decreasing Al3+ levels in the same soil. In TQ soils, the effects were more limited, showing specific increases in pH, P, S–SO 4 2-, and Si levels. Moreover, there was a 21% increase in SBR in OX with higher basalt rates. These findings suggest that basalt powder has the potential to serve as an environmentally friendly solution for soil fertilization, positively impacting its chemical and biological properties. [Display omitted] • Basalt powder application increased soil pH and most nutrient contents. • Higher basalt doses reduced Al3+ contents in soil. • Basalt powder enhanced soil basal respiration by 21%. • Study suggests basalt powder as eco-friendly soil fertilizer. [ABSTRACT FROM AUTHOR]

Microorganisms quickly colonise microplastics entering the ocean, forming a biofilm that, if ingested, is consumed with the microplastics. Past research often neglects to expose fish to biofouled microplastics, opting only for clean microplastics despite the low likelihood that fish will encounter clean microplastics. Here, we investigate the physiological impacts of biofouled polyethylene microplastic (300–335 μm) exposure in juvenile fish. Intermittent flow respirometry, antioxidant enzyme activity, and lipid peroxidation were investigated after fish were exposed to clean, biofouled, or no microplastic beads. Fish exposed to biofouled microplastics had a wider aerobic scope than those exposed to clean microplastics while antioxidant enzyme and lipid peroxidation levels were higher in clean microplastics. Clean microplastic exposure indicated higher fitness costs, potentially due to a nutritional advantage of the biofilm or varying bioavailability. These findings highlight the importance of replicating natural factors in exposure experiments when predicting the impacts of increasing pollutants in marine systems. [Display omitted] • Clean microplastic cause higher antioxidant enzymes in juvenile fish than biofouled. • Narrower aerobic scope in juvenile fish from clean, not biofouled, microplastic. • Biofouled microplastic cause different physiological responses to clean microplastic. [ABSTRACT FROM AUTHOR]

Aerobic training can improve vascular endothelial function in-vivo. The aim of this study was to elucidate the mechanisms underlying this improvement in isolated human microvascular endothelial cells. Sedentary males, aged 57 ± 6 years completed 8 weeks of intense aerobic training. Resting muscle biopsies were obtained from the thigh muscle and used for isolation of endothelial cells (pre n = 23, post n = 16). The cells were analyzed for mitochondrial respiration, H 2 O 2 emission, glycolysis, protein levels of antioxidants, NADPH oxidase, endothelial nitric oxide (NO) synthase and prostacyclin synthase (PGI 2 S). In-vivo microvascular function, assessed by acetylcholine infusion and arterial blood pressure were also determined. Endothelial mitochondrial respiration and H 2 O 2 formation were similar before and after training whereas the expression of superoxide dismutase and the expression of glutathione peroxidase were 2.4-fold (p = 0.012) and 2.3–fold (p = 0.006) higher, respectively, after training. In-vivo microvascular function was increased by 1.4-fold (p = 0.036) in parallel with a 2.1-fold increase in endothelial PGI 2 S expression (p = 0.041). Endothelial cell glycolysis was reduced after training, as indicated by a 65% lower basal production of lactate (p = 0.003) and a 30% lower expression of phosphofructokinase (p = 0.011). Subdivision of the participants according to blood pressure at base-line (n = 23), revealed a 2-fold higher (p = 0.049) rate of H 2 O 2 production in endothelial cells from hypertensive participants. Our data show that exercise training increases skeletal muscle microvascular endothelial cell metabolism, antioxidant capacity and the capacity to form prostacyclin. Moreover, elevated blood pressure is associated with increased endothelial mitochondrial ROS formation. [Display omitted] • High resolution respirometry of human muscle microvascular endothelial cells • Endothelial cell expression of SOD and GPX-1 is enhanced by exercise training • Hypertension is associated with higher levels of ROS in endothelial cells • Endothelial cell glycolysis is reduced by exercise training [ABSTRACT FROM AUTHOR]

Despite the growing use of hybrid catfish (Ictalurus punctatus × I. furcatus) in the aquaculture industry, few studies have compared their physiological performance with more commonly reared channel catfish (I. punctatus) and their other parent stock, blue catfish (I. furcatus). An understanding of metabolic scope and swimming performance, particularly in elevated water temperatures, is important because these metrics directly relate to the overall performance or fitness of an organism. Therefore, metabolic scope, the difference between standard metabolic rate (SMR) and maximum metabolic rate (MMR), and swimming performance in channel, blue, and hybrid catfish were compared using intermittent and swim-flume respirometry coupled with U crit protocols at moderate (23 °C) and high (33 °C) temperatures. It was hypothesized hybrid catfish would have larger metabolic scope and greater swimming performance than channel and blue catfish due to heterosis from hybridization. Hybrid catfish SMR did not differ from blue catfish, while hybrid catfish had higher MMR, larger metabolic scope, and better swimming performance than channel and blue catfish. These results indicate hybrid catfish outperform channel and blue catfish, in terms of swimming performance, presumably due to larger metabolic scope over moderate to high temperatures. • Hybrid catfish outperform channel and blue catfish due to larger metabolic scope. • Hybrid catfish have better swimming performance than channel and blue catfish. • Temperature has a profound effect on metabolic rate but not swimming performance. [ABSTRACT FROM AUTHOR]

Major depressive disorder (MDD) has been associated with lower mitochondrial energy production and higher oxidative stress. We investigated whether these alterations manifest in patients with current mild to moderate MDD severity. We observed no differences in mitochondrial respiration and density (i.e., c itrate-synthase activity) in peripheral blood mononuclear cells and oxidative stress markers (i.e., 8-hydroxy-2′-deoxyguanosine, 8-isoprostane) in blood serum of 20 female MDD patients compared to 24 non-depressed women. Alterations in mitochondrial energy production and oxidative stress did not linearly depend on the current severity of MDD. However, biological alterations might rather manifest with higher MDD severity/chronicity and at higher age. [ABSTRACT FROM AUTHOR]

This present study considered the evaluation of the feasibility of combining an electrocoagulation (EC) process with a biological treatment for cutting oil emulsions (COE) biodegradation. The optimization of the EC process by means of the second-order model obtained using a central composite design methodology led to the following optimal conditions: an initial pH of 5.8, a current density of 241 A m-2 and an electrolysis time of 29 min. Under these optimal conditions, chemical oxygen demand (COD), and turbidity reductions were, respectively, 97.42% and 99.97%. Despite the significant reduction in pollution, the final COD values remained always high. Therefore, the effluents pretreated by electrocoagulation were then treated in an aerobic bioreactor coupled to a sequential respirometer for 52 d. The obtained results were very satisfactory showing an additional COD reduction of more than 98.5%, accompanied by a good biomass activity (40 mg O2 L-1 h-1) for the pretreated COE. Moreover, the non-pretreated COE solutions reached COD reduction of 94% during 33 d of running after 52 d of the biomass acclimatization period. A total COD removal of 99.8% was obtained with a residual value of 177 mg L-1, indicating the success of a biological treatment combined to an electrocoagulation pretreatment process. [ABSTRACT FROM AUTHOR]

• The variant m.9032T > C variant in MT-ATP6 encoding p.(Leu169Pro) is pathogenic. • At high heteroplasmy levels the variant caused microcephaly, ataxia, hearing loss, and lactic acidosis in early childhood. • This variant is recognizable by abnormal fragment F 1 of complex V on blue native gel electrophoresis. Diagnosing complex V deficiencies caused by new variants in mitochondrial DNA is challenging due to the rarity, phenotypic diversity, and limited functional assessments. We describe a child with the m.9032T > C variant in MT-ATP6 encoding p.(Leu169Pro), with primary presentation of microcephaly, ataxia, hearing loss, and lactic acidosis. Functional studies reveal abnormal fragment F 1 of complex V on blue native gel electrophoresis. Respirometry showed excessively tight coupling through complex V depressing oxygen consumption upon ADP stimulation and an excessive increase following uncoupling, in the presence of upregulation of mitochondrial biogenesis. These data add evidence about pathogenicity and functional impact of this variant. [ABSTRACT FROM AUTHOR]

•Chicken manure, alperujo, olive leaves/pruning and cereal straw were co-composted. •Lignocellulosic wastes reduced the odour emissions derived from chicken manure. •Physico-chemical, respirometric and olfactometric variables were properly monitored. •The compost obtained was stabilised, sanitised and rated as Compost type A. •The average global odour emission rate of the composting plant was 5.16 ou E /kg. Co-composting is a simple and inexpensive alternative for stabilizing and reducing jointly different biodegradable waste. In this study, the feasibility of co-composting chicken manure (CM), alperujo (AL), olive leaves/pruning (OL) and cereal straw (CS) was evaluated at full-scale. The different areas of a composting plant such as fermentation area, composting area and leachate lagoon, were evaluated from physico-chemical, respirometric and olfactometric points of view. The compostable mixture was previously subjected to anaerobic fermentative pretreatment to hydrolyse the non-easy biodegradable organic matter and favour the subsequent composting process. The physico-chemical, respirometric and olfactometric characterization of the composted mixture showed a high-quality final product characterized by a 57 % average organic matter content, an adequate metal content (Compost type A) and a suitable microbiological stability (SOUR max value of 14 mmol O 2 /kg VS h), complying with current national legislation for use as fertilizer in agriculture. Furthermore, the average global odour emission rate of the composting plant was 5.16 ou E /kg, considering the total mass of the compostable mixture and the time required to be treated. Finally, the leachate collected from different treatments of the compostable mixture was found to be a stabilized organic liquid waste with a high nutrient content, useful for wetting composting piles. [ABSTRACT FROM AUTHOR]

• Leachate biodegradability was assessed for autochthonous and allochthonous biomasses. • Leachate biodegradability strongly depended on the biomass used to perform the tests. • Autochthonous biomass enabled a higher biodegradation capacity (75% vs 40%). • Autochthonous biomass exhibited a higher resistance to inhibitory leachate compounds. • Allochthonous biomass required the supply of an organic co-substrate. The biodegradability and treatability of a young (3 years old) municipal landfill leachate was evaluated by means of chemical oxygen demand (COD) fractionation tests, based on respirometric techniques. The tests were performed using two different biomasses: one cultivated from the raw leachate (autochthonous biomass) and the other collected from a conventional municipal wastewater treatment plant after its acclimation to leachate (allochthonous biomass). The long term performances of the two biomasses were also studied. The results demonstrated that the amount of biodegradable COD in the leachate was strictly dependent on the biomass that was used to perform the fractionation tests. Using the autochthonous biomass, the amount of biodegradable organic substrate resulted in approximately 75% of the total COD, whereas it was close to 40% in the case of the allochthonous biomass, indicating the capacity of the autochthonous biomass to degrade a higher amount of organic compounds present in the leachate. The autochthonous biomass was characterized by higher biological activity and heterotrophic active fraction (14% vs 7%), whereas the activity of the allochthonous biomass was significantly affected by inhibitory compounds in the leachate, resulting in a lower respiration rate (SOUR = 13 mg O 2 gVSS−1 h-1 vs 37 mg O 2 gVSS−1 h−1). The long-term performance of the autochthonous and allochthonous biomasses indicated that the former was more suitable for the treatment of raw landfill leachate, ensuring higher removal performance towards the organic pollutants. [ABSTRACT FROM AUTHOR]

• A liquid phase stability test (MANLIQ) was compared to 2 solid-phase stability tests. • The respiration indices' order was: Dynamic > MANLIQ ≥ Static. • The strongest correlation was between the liquid and the static solid-phase indices. • The ratio of the liquid indices to the static solid-phase indices was 1.6–2.7. • The solid phase tests should be preferred over the liquid test to assess stability. Goal of the work was to compare the respiration activities, as measured via oxygen consumption with three different organic waste stability methods so that to propose the optimal one. The novelty of the work is that there exists no comparison of solid-phase with liquid-phase stability assessment techniques in the literature. The respiration activities were assessed using two solid-phase methods and a manometric liquid-phase method (MANLIQ) performed on twenty-seven organic substrates. The methods rely on measuring oxygen consumption (uptake) via pressure drops (liquid-phase test, static solid-phase test) or via direct O 2 measurements on the gaseous phases at the inlet and outlet of the respirometer (solid-phase dynamic test). A positive statistically significant correlation was calculated between the MANLIQ and the static solid-phase indices. The maximum rate MANLIQ index for the raw substrates was 2900 mg O 2 kg−1 VS h−1, while most of the processed substrates had cumulative MANLIQ indices below 160 g O 2 kg−1 VS. The ratio of the liquid indices to the static solid-phase indices ranged from 1.6 to 2.7 and the ratio of the liquid indices to the dynamic solid-phase indices ranged from 0.2 to 0.4. The MANLIQ method failed to result in a good correlation of the processing time with the respiration indices. On the other hand, a correlation was more visible in the two solid-phase tests, despite the large variability of the types and sources of the substrates. Therefore, the solid-phase methods should be preferred over the liquid-phase method to assess stability for various organic substrates. [ABSTRACT FROM AUTHOR]

Corrosion of aluminium alloy 6063-T6 with exposure to simulated steel corrosion products using ferric chloride droplets was investigated. Focus of these experiments was to understand the role of oxygen in the redox process; therefore, samples were exposed to standard atmospheric conditions as well as to oxygen-derived conditions. Respirometric measurements indicate that the hydrogen evolution reaction (HER) is the dominant cathodic reaction. Especially in the initial stages when the corrosion rates are the highest, the HER occurs almost exclusively. At the later stages the oxygen reduction reaction (ORR) barely takes over as the main cathodic reaction. The dissolved volumes and maximum corrosion depths determined with X-ray Computed Tomography (XCT) were more significant for those samples deprived of oxygen. The composition of iron-rich deposits formed consisted of magnetite and maghemite, supporting exposure conditions where reactions were deprived of oxygen. • Respirometric measurements highlight the critical role of the hydrogen evolution reaction (HER) in the studied process. • The HER emerges as the primary cathodic reaction during the initial exposure stages, leading to the highest corrosion rates. • Utilising XCT and Respirometric measurements; researchers uncover valuable insights into the role of O 2 in the redox process. • O 2 deprived conditions exhibit amplified dissolved volumes and corrosion depths, indicating the HER's dominance. [ABSTRACT FROM AUTHOR]

• A comparative study into respiratory markers was conducted with 4 d and 12 d old zebrafish. • Modulation of respiratory markers was observed mainly in 12 d old early gill-breathing larvae. • Onset of gill respiration corresponds to increased neurotoxicant mediated lethality. • The respiratory failure syndrome (RFS) is most likely the reason for observed higher sensitivity of older stages. Neurotoxic compounds can interfere with active gill ventilation in fish, which might lead to premature death in adult fish, but not in skin-breathing embryos of zebrafish, since these exclusively rely on passive diffusion across the skin. Regarding lethality, this respiratory failure syndrome (RFS) has been discussed as one of the main reasons for the higher sensitivity of adult fish in the acute fish toxicity test (AFT), if compared to embryos in the fish embryo toxicity test (FET). To further elucidate the relationship between the onset of gill respiration and death by a neurotoxic mode of action, a comparative study into oxygen consumption (MO 2), breathing frequency (f v) and amplitude (f ampl) was performed with 4 d old skin-breathing and 12 d old early gill-breathing zebrafish. Neurotoxic model substances with an LC 50 FET/AFT ratio of > 10 were used: chlorpyrifos, permethrin, aldicarb, ziram, and fluoxetine. Exposure to hypoxia served as a positive control, whereas aniline was tested as an example of a narcotic substance interfering non-specifically with gill membranes. In 12 d old larvae, all substances caused an increase in MO 2 , f v and partly f ampl , whereas effects were minor in 4 d old embryos. An increase of f v in 4 d old embryos following exposure to chlorpyrifos, aldicarb and hypoxia could not be correlated with an increased MO 2 and might be attributed either to (1) to the successfully postponed decrease of arterial partial pressure of oxygen (PO 2) through support of skin respiration by increased f v , (2) to an unspecific stimulation of the sphincter muscles at the base of the gill filaments, or (3) to the establishment of oxygen sensing for later stages. In gill-breathing 12 d old zebrafish, a concentration-dependent increase of f v was detected for aniline and chlorpyrifos, whereas for aldicarb, fluoxetine and permethrin, a decline of f v at higher substance concentrations was measured, most likely due to the onset of paralysis and/or fatigue of the gill filament sphincter muscles. Since alterations of f v serve to postpone the decrease in arterial PO 2 and MO 2 increased with decreasing f v , the respiratory failure syndrome could clearly be demonstrated in 12 d old zebrafish larvae. Passive respiration across the skin in zebrafish embryos could thus be confirmed as a probable reason for the lower sensitivity of early life-stages to neurotoxicants. Integration of respiratory markers into existing testing protocols with non-protected developmental stages such as embryos might help to not underestimate the toxicity of early life-stages of fish. [Display omitted] [ABSTRACT FROM AUTHOR]

The present article deals with the calibration and validation of a biological model of SMBR for hospital wastewater treatment using respirometry. In a first part, the stoichiometric and kinetic parameters are estimated and validated using the experimental oxygen uptake rate (OUR) profiles from the sodium acetate degradation process, according two kinetic theories: one considering that microorganisms use the carbon reserve and easily biodegradable substrates simultaneously for growth; and the other that microorganisms use the carbon reserve only when easily biodegradable substrate is depleted. In this study, the first theory proved to be the most adequate to predict the experimental OUR profile. In the second part, the hospital wastewater degradation process simulated using the theory determined as the more suitable. The stoichiometric parameters obtained for acetate were used for the hospital wastewater COD fractionation process, considering simultaneous growth and substrate storage. These COD fractions and the stoichiometric parameters obtained for acetate were employed for the simulation process of hospital wastewater degradation, where only kinetic parameters were calibrated. Good correspondence was obtained between experimental data and the model outputs. The values obtained for kinetic parameters were different from those obtained for sodium acetate, evidencing the influence of the substrate nature. Through the calibration of stoichiometric and kinetic parameters using the proposed procedure, the activated sludge models proved their capacity and usefulness for the simulation of a hospital wastewater degradation process. [ABSTRACT FROM AUTHOR]

A simple balancing method using passive samplers over a week's period has been developed and tested successfully to determine elimination rates of 22 common micropollutants of household and industrial sources in 18 full-scale wastewater treatment plants of different design and performance. Independent reactor tests to delineate elimination rates with native sludge of the treatment plants correlated very well with the full-scale elimination rate determinations. As opposed to common assumptions, this large dataset indicated that shorter sludge retention times – read: higher active biomass – showed higher micropollutant elimination rates in many cases. Multivariate statistical analysis of the elimination rates over the 18 treatment plants was able to group compounds according to common degradation pathways and showed that sensitivity to SRT drove the grouping. The dataset also allowed to determine population equivalent normalized loads of the investigated micropollutants. The application of WWTP balancing with passive sampling makes it relatively easy to gather elimination rates and inlet loads on a much broader basis than before and gives orientation for more in-depth analysis of degradation pathways. Image 1 • There is a need for accurate micropollutant elimination data at plant scale. • Passive sampling provides elimination rates based on a conservative tracer correction. • Elimination rates allowed clustering compounds into groups with consistent degradation schemes. • The statistical grouping was driven by negative correlations with sludge retention times. [ABSTRACT FROM AUTHOR]

Highlights • A biofilm airlift reactor filled with Raschig rings in the downcomer section was used. • The biofilm reactor was operated at several liquid superficial velocities. • Kinetic and stoichiometric parameters were determined by in situ pulse respirometry. • Internal and external resistance as well as effectiveness factors were determined. • External mass transfer accounted for up to 70% of the total mass transfer resistance. Abstract An airlift reactor filled with Raschig rings in the downcomer section only was designed to allow for the characterization of biofilm biomass at several superficial liquid velocities. The reactor was inoculated with activated sludge and operated with synthetic wastewater containing acetate. After steady state was reached, the kinetic parameters of the process were determined at each superficial liquid velocity by an in-situ pulse respirometry method. Subsequently, the biofilm contained in the reactor was disaggregated, resuspended in a mineral medium, and reintroduced in the reactor, without Raschig rings, i.e., a standard airlift reactor. The kinetic parameters of the bioprocess were determined again, by the same respirometry method. That strategy allowed for the estimation of apparent and intrinsic kinetic parameters; i.e., with and without mass transfer limitation, respectively. Moreover, the method also allowed for the determination of the internal and external effectiveness factors and mass transfer resistances. The results shown that the hydrodynamic conditions had a strong effect on the kinetic parameters but none on the stoichiometric parameters. The external mass transfer accounted for up to 70% of the total mass transfer resistance. It is concluded that respirometry is a useful tool for the characterization of biofilms, in actual random packing reactors. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the occurrence of storage mechanisms in biofilm from constructed wetlands (CWs) through respirometric studies and calculated the corresponding heterotrophic growth yields. Respirometric tests were performed in biofilm extracted from horizontal sub-surface flow CWs batch loaded with three different COD mass loads: 7.0., 15.6 and 35.2 g COD/(m2∙day). The bed removal efficiency remained above 96% for all mass loads and COD mass removal rates increased from 6.8 g COD/(m2∙day) for the lowest load to 34.5 g COD/(m2∙day) for the highest load. The percentage of tests with storage evidence decreased from 85% to 10% with increasing mass loads and the responses of the microbial community to the acetate pulse showed an adaptation to the feast-famine conditions, through storage mechanisms, for lower loads, and a metabolic shift to the use of COD for growth for higher loads. Heterotrophic biomass yield values varied from 0.54–0.56 g COD/g COD for low mass loads to 0.69–0.71 for higher mass loads, indicating that greater substrate availably triggers growth and reduces the occurrence of storage. Storage yield values supported this trend varying between 0.89 and 0.94 with increasing mass loads. Given the significant storage evidence obtained in the present study, it is suggested that a modified modelling architecture, which includes storage mechanisms, should be considered in future simulations of CW systems. Graphical abstract Unlabelled Image Highlights • Storage evidence was found in biofilm from constructed wetlands. • Storage decreased with COD mass load increase. • Heterotrophic growth yield and storage yield increased with COD mass load increase. • Storage evidence suggests heterotrophic bacteria modelling could be modified. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Respirometry was suitable for the nitrification inhibition assessment. • Fenton and ozone oxidation showed excellent performance for nitrification detoxication. • NH 3 -N was effectively removed by integrating advanced oxidation process and biodegradation. • Compounds with hydrophobicity, large molecule, and aromatic/unsaturated structures may cause inhibition. Abstract The excess emission of ammonia nitrogen is a common issue encountered by many industry wastewater treatment plants, due to the elevated concentrations and toxicities of compounds released from a large number of industries which might inhibit the growth of nitrifying bacteria. In this work, we are aiming at addressing the above issue raised by an industry wastewater treatment plant and elucidating the nitrification inhibitory mechanisms. A straight-forward and reliable method i.e., respirometry, was developed for the characterisation of nitrification inhibition. The pretreatment methods of Fenton and ozone oxidations and iron carbon micro electrolysis have been attempted to reduce the nitrification inhibition and the former two turned out to be effective. The nitrification inhibition rate (NIR) of the wastewater after Fenton oxidation was reduced from 87% to 13.6% with the optimized condition (pH = 3.0, H 2 O 2 dosage of 14.7 mM, Fe2+ dosage of 4.90 mM, and reaction time of 20 min). The optimal parameters for ozonation were: pH = ∼8.2 (original pH of wastewater), reaction time of 25 min (equivalent to an ozone dosage of 381 mg/L), under which the NIR was declined to 12.7%. The nitrification inhibition might be attributed to the presence of compounds with hydrophobic properties, high molecular weight, and aromatic and unsaturated structures in industry wastewater. The coupling use of Fenton-SBR and ozone-SBR achieved NH 3 -N removal efficiency of 98% and 93%, respectively. The effluent NH 3 -N finally met with the Integrated Wastewater Discharge Standard (DB31/199-2009). [ABSTRACT FROM AUTHOR]

Abstract This work analyzes the effect of nalidixic acid (NAL) on the kinetics of the heterotrophic and autotrophic biomass growth within a "NIPHO" activated sludge reactor treating municipal wastewater. Thus, the effect of this chemical in the degradation rates of carbon and nitrogen sources and net biomass growth rate is evaluated. Activated sludge samples were taken at three different operation conditions, changing the values of hydraulic retention time (2.8–3.8 h), biomass concentration (1400–1700 mgVSS L−1), temperature (12.6–14.8 °C), and sludge retention time (11.0–12.6 day). A respirometric method was applied to model the kinetic performance of heterotrophic and autotrophic biomass in absence and presence of NAL, and a multivariable statistical analysis was carried out to characterize the influence of the operation variables on the kinetic response of the system, which was finally optimized. The results showed that there was no inhibitory effect of NAL on heterotrophic biomass, with an increase of net heterotrophic biomass growth rate from 1.70 to 6.73 mgVSS L−1 h−1 at the most favorable period. By contrast, the autotrophic biomass was negatively affected by NAL, reducing the value of net autotrophic biomass growth rate from 25.37 to 10.29 mgVSS L−1 h−1 at the best operation conditions. In general, biomass concentration and temperature had the highest influence on the degradation rate of carbon and nitrogen sources, whereas hydraulic retention time and sludge retention time were the most influential on net heterotrophic and autotrophic biomass growth rates. Highlights • NAL affects heterotrophic and autotrophic kinetics in a NIPHO reactor. • Rates of carbon sources removal and net heterotrophic growth increased with NAL. • Rates of nitrogen sources removal and net autotrophic growth decreased with NAL. • X VSS and T affect substrate degradation rate; HRT and SRT influence growth rate. • Modeling and optimization strategies applied to NIPHO activated sludge reactor. [ABSTRACT FROM AUTHOR]

Highlights • Encapsulated calcium nitrate (ECN) can be used as a substitute for soybean meal. • The maximum quantity of ECN for goat diets might be 10 g/kg on a dry matter basis. • This is the maximum quantity that did not constrain dry matter intake. • Ingestion of ECN reduces fast heat production in goats. Abstract Encapsulated calcium nitrate (ECN) has been studied as a source of non-protein nitrogen (NPN) that establishes an alternative sink of free hydrogen in the ruminal environment and, consequently, reduces the emission of methane and probably improves efficiency of energy use. The aim of this study was to assess the impact of ECN as a substitute for soybean meal (SBM) in energy partition, substrate oxidation, and microbial nitrogen (MicN) synthesis. Twelve growing castrated male goats (21.9 kg ± 3.19 kg of initial body weight) were used in four 3 × 3 Latin squares (LS) during three 48-d periods. Goats were grouped by body weight (BW) within each LS and randomly assigned to one of three diets: SBM – control based on SBM, 75 g/kg of SBM on dry matter (DM) basis; ECN12.5 – 12.5 g/kg of ECN on DM basis; and ECN25 – 25 g/kg of ECN on DM basis. Each period included 21 days for adaptation, five days for metabolism trials (d 22 to d 26), and 15 days for indirect calorimetry trials (d 27 to d 41). At the end of each period, a 7-day washout interval was provided during which the goats were fed SBM diet. The goats showed no symptoms of intoxication based on methemoglobin (MetHb) levels (0.7% ± 0.17 of total hemoglobin). Heat production (HP) was not influenced by treatments (P = 0.91), but fast heat production (FHP) was 22% (P < 0.05) lower in ECN25 than in SBM. Methane emission decreased by 0.21 g for each g of nitrate intake. The inclusion of 9.5 g/kg of ECN on DM resulted in a maximum DE and ME intake. The total retained N decreased linearly (P < 0.05) with the increase of ECN; however, microbial nitrogen (MicN) synthesis did not differ between treatments. In conclusion, the use of ECN as a replacement for SBM decreased FHP, which might spare energy for growth. The use of ECN as a substitute for SBM did not affect MicN synthesis. The inclusion of 9.5 g/kg of ECN on DM basis results in maximum DMI, DE, and ME intake in growing goats. [ABSTRACT FROM AUTHOR]

Abstract Oviparous reptile embryos must tolerate fluctuations in oxygen availability and incubation temperature during development. In this study, regional hypoxia was simulated by painting eggs of Eublepharis macularius with melted paraffin wax to decrease the available surface area for gas exchange by approximately 80%. Experimental and control eggs were incubated at either 28 or 34 °C and embryo mass, stage, heart mass, relative heart mass, and oxygen consumption (V̇O 2) were measured at 15 and 30 days of incubation. Embryo mass from the regional hypoxia treatment was reduced by about 50% at day 15 and by about 30% at day 30 of incubation, independent of incubation temperature compared to controls. Embryo stage from the regional hypoxia treatment was reduced by about 2 stages at day 15 independent of incubation temperature but there was no effect of hypoxia treatment at day 30. Absolute heart mass was reduced by about 60% in regional hypoxia embryos sampled at day 15 while relative heart mass was increased by about 30% in regional hypoxic embryos at day 30 compared to controls, suggesting that heart mass is conserved at the expense of somatic growth. Embryo V̇O 2 was affected by incubation temperature at both 15 and 30 days of incubation but not by regional hypoxia treatment. These results indicate that embryos of E. macularius possess plasticity in their capacity to respond to reduction in oxygen availability during incubation, and are able to survive and continue developing when gas exchange surface area is severely limited. Highlights • Gecko embryos tolerate wide fluctuations in O2 and temperature • Embryos continue development despite 80% reduction in respiratory membrane • Regional hypoxia results in retarded development and reduced embryo mass • There is no interactive effect of temperature and hypoxia on embryo development • During late development heart mass is maintained at the expense of somatic growth [ABSTRACT FROM AUTHOR]

Abstract The aquatic habitats of the Amazon basin present dramatic variation of oxygen level, and, to survive such changes, many aquatic animals developed biochemical and physiological adaptations. The advanced teleost Astronotus crassipinnis (Perciformes) is a fish tolerant to hypoxia and known to endure such naturally variable environments. Hypoxia-Inducible factor-1α (hif-1α) is among the most important and studied genes related to hypoxia-tolerance, maintaining regular cellular function and controlling anaerobic metabolism. In the present work, we studied hif-1α expression and related it to changes in metabolic pathways of Astronotus crassipinnis exposed to 1, 3 and 5 h of hypoxia, followed by 3 h of recovery. The results show that A. crassipinnis depresses aerobic metabolic under hypoxia, with a decrease in glycolysis and oxidative enzyme activities, and increases its anaerobic metabolism with an increase in LDH activity coupled with a decrease in oxygen consumption, which indicates an increase in anaerobic capacity. In addition, the animal differentially regulates hif-1α gene in each tissue studied, with a positive relationship to its metabolic profile, suggesting that hif-1α might be one of the most important induction factors that regulate hypoxia tolerance in this species. [ABSTRACT FROM AUTHOR]

The increasing demand for pikeperch ( Sander lucioperca) from recirculating aquaculture systems (RAS) has raised the need for detailed knowledge on water quality parameters. Nitrate thresholds are of interest as nitrate accumulates in RAS and influences fish physiology. The trial was conducted in a recirculating aquaculture respirometer with pikeperch (average body weight (BW) 367 ± 1.1 g) successively reared at three different nitrate-nitrogen (NO 3 –N) concentrations (N30: 30 mg L −1 , N120: 120 mg L −1 and N240: 240 mg L −1 ) and compared to a control group reared at the lowest possible nitrate-nitrogen concentration (N0: 5 mg L −1 ). Pikeperch were fed once per day with a commercial diet at three different feeding levels corresponding to 0.3% BW, 0.6% BW and 0.9% BW in triplicates for 8 days at either nitrate-nitrogen concentration before fasting for additional 3 days. Oxygen consumption and ammonia excretion were measured for 22-h in fed and fasting pikeperch to examine the influence of nitrate on energy metabolism. Metabolisable energy, retained energy and digestible energy requirements for maintenance (DE m ) as well as the efficiency for energy utilisation (k g ) and relative protein utilisation for energy metabolism (as ammonia quotient (AQ)) were determined. Specific dynamic action (SDA) was calculated to estimate the amount of energy spend on ingestion, digestion, absorption and assimilation of feed at different nitrate levels. SDA was significantly increased in the N240 treatment. Results of DE m showed a significant difference between N30 and N120 with DE m of N120 being about 73% higher than DE m of N30. The efficiency k g was significantly decreased between N240 and both N120 and N30 by 10% and 11% respectively. Increased values in AQ in the feed depleted fish in the N240 treatment indicates that fasting pikeperch in the high nitrate treatment had to use body protein to fuel an average of 46 ± 7% of their energy metabolism. The results of this trial show that pikeperch tolerate NO 3 –N concentrations of up to 240 mg L −1 but energy requirements are most favourable at concentrations of 30 mg L −1 NO 3 –N. [ABSTRACT FROM AUTHOR]

Abstract Over the last few decades, plastic waste has become an increasing environmental concern as it accumulates in every environment on our planet. Though traditionally seen as a macroscopic problem (i.e., large plastic debris), plastic pollution is also evident at smaller scales. Indeed, the intentional industrial production of small plastic particles and the physical degradation of larger plastic debris have overtime resulted in an increased environmental prevalence of smaller plastic particles, including microplastics. While the effects of these small polymers on marine biota have been an important research focus, recent global surveys indicate that our freshwater lakes and rivers are also plagued by microplastics. However, despite these discoveries we currently have a limited understanding of the impact these particles may have on freshwater animals, particularly on vertebrate species. Thus, the aim of the present study was to assess the impact of high concentrations of microplastics (5 and 20 mg.L−1) on the early life stages in zebrafish, a model freshwater vertebrate model. To do this, we exposed embryonic and larval zebrafish to fluorescently labelled polyethylene microspheres for up to 14 days and assessed their microplastic content, growth, hatching and oxygen consumption rates. We then explored the molecular underpinnings of the microplastic response by RNA sequencing. Over the course of the exposure, we observed a consistent accumulation of microplastics in the gastrointestinal tract of the fish in a concentration dependent manner, but could not detect any detrimental effects of these particles on larval development, growth or metabolism. However, whole animal transcriptomics revealed that microplastics induced a transient and extensive change in larval gene expression within 48 h exposure, which largely disappeared by 14 days. However, as these transcriptional changes occurred during a critical period of larval development, we suggest that an evaluation of the potential long-term impact of these particles is warranted. Graphical abstract Image 1 Highlights • No effects of MP (microplastics) on hatching, mortality and growth in zebrafish • No effects of MP on O 2 consumption rates • Large transcriptomic changes after 2 days of MP exposure • Downregulated genes involved with neural development and function • Most gene expression differences disappeared at 14 days of MP exposure Short term exposure of developing zebrafish to polyethylene microplastics induces extensive transcriptomic perturbations with no apparent immediate effects on larval development and physiology. [ABSTRACT FROM AUTHOR]

• Ultrasound (US) pulses and backwashing were combined for membrane fouling control in MBR system. • A slight worsening of effluent quality was observed with 20kHz of US frequency. • The application of US to clean MBR membranes did not cause biomass deflocculation. • The application of US to clean MBR membranes did not alter activated sludge characteristics. • Alteration in the biological activity of the activated sludge by US application was not relevant. The influence of ultrasound (US) irradiation applied for membrane fouling control of a membrane bioreactor (MBR) over the physico-chemical and biological characteristics of the activated sludge was analysed. Three parallel MBR modules coupled to a sonicator which provided US irradiation at 20, 30 and 40kHz (fixed power 0.5W/L) were evaluated. The modules were fed with activated sludge from a conventional MBR. Particle size distribution (PSD), exopolysaccharide substances, soluble microbial products, biomass concentration and kinetic and stoichiometric parameters were assessed. The combination of 2s US pulses every 3min of filtration with 1min of backwashing with 3s of coarse bubble aeration achieved good results in membrane fouling control. A slight worsening of the effluent quality was observed for the sonicated MBR modules with respect to a conventional MBR, mainly for the 20kHz module, which showed the worst transmembrane pressure control. A slight activated sludge PSD displacement towards larger sizes was observed for all frequencies, but the characteristics of the activated sludge was not significantly altered, so the worsening of the effluent quality or membrane fouling were not related to the effect of US irradiation on biomass. Alteration in the biological activity was not relevant. [Display omitted] [ABSTRACT FROM AUTHOR]

• Reliable respirometric method for determination of biodegradation of biogenic polymers. • Determination of system boundaries, limits and calibration of the respirometric system. • Particle size is crucial for hardly biodegradable material such as polylactic acid. • High water solubility of proteins improves biodegradation. • Increased biodegradation of polylactic acid reinforced with microfibrillated cellulose compared to neat polylactic acid. The biodegradation of polymers can be determined by measuring the CO 2 evolution from the biodegradation medium, for example soil. In this work, the biological degradation of cellulose (powder and fibers), polylactic acid (PLA, powder and films), a combination of both and lupin protein isolate (LPI, films) was investigated. Therefore, a reliable method using a respirometric system needed to be developed. The soil to sample ratio, the system boundaries concerning the maximum CO 2 uptake and O 2 consumption in addition to the change in electrical conductivity of the KOH absorbant solution caused by CO 2 uptake were investigated. LPI-based films showed the highest biodegradation in %, followed by regenerated cellulose fibers (RC fibers). In case of PLA only the samples with powder morphology were biological degraded. The degradation of PLA films was highly increased to 68 % by addition of microfibrillated cellulose (MFC). The samples were analyzed before and after biodegradation using scanning electron microscopy (SEM) and gel permeation chromatography (SEC). The developed method was successful to validate the degree of biodegradation for a large variety of biogenic polymers and can be generally applied. [ABSTRACT FROM AUTHOR]

Ectotherms survive exposure to subzero temperatures through freeze tolerance or freeze avoidance. Among vertebrate ectotherms, glucose is commonly used as a cryoprotectant in freeze tolerant strategies and as an osmolyte in freeze avoidant strategies, while also functioning as a metabolic substrate. Whereas some lizard species are capable of both freeze tolerance and freeze avoidance, Podarcis siculus is limited to freeze avoidance through supercooling. We hypothesized that, even in a freeze-avoidant species such as P. siculus , plasma glucose would accumulate with cold acclimation and would increase in response to acute exposure to subzero temperatures. To investigate this, we tested whether plasma glucose concentration and osmolality would increase in response to a subzero cold challenge before and after cold acclimation. In addition, we examined the relationship between metabolic rate, cold acclimation, and glucose by measuring metabolic rate during the cold challenge trials. We found that plasma glucose increased during the cold challenge trials, and that the increase was more pronounced after cold acclimation. However, baseline plasma glucose decreased throughout cold acclimation. Interestingly, total plasma osmolality did not change, and the increase in glucose only slightly altered freezing point depression. Metabolic rate during the cold challenge decreased after cold acclimation, and changes in respiratory exchange ratio suggest an increased relative use of carbohydrates. Overall, our findings demonstrate an important role for glucose in the response of P. siculus to an acute cold challenge, thus adding evidence for glucose as an important molecule for overwintering ectotherms that use freeze avoidant strategies. [Display omitted] • P. siculus does not accumulate plasma glucose or cryoprotectants during cold acclimation. • P. siculus increases plasma glucose, but not plasma osmolality in response to an acute cold challenge. • P. siculus decreases respiratory metabolism following cold acclimation. • P. siculus increases respiratory exchange ratio following cold acclimation. [ABSTRACT FROM AUTHOR]

We describe a new sensor platform for simple on-site analysis of total aerobic viable counts (TVCs) in food samples, which uses disposable sealable plastic sachets with phosphorescent oxygen sensor inserts and liquid growth media. Food samples are collected, placed directly in the sachets, which are then sealed and incubated at 30 °C while monitoring (hourly or endpoint) sensor signals non-invasively with a commercial handheld reader FirestingO2. The growth of microbiota produces characteristic respiration profiles, from which sample initial TVC load is quantified: the Threshold Time (TT, in hours), when the sensor signal reaches the set signal threshold, is determined and calibration equation is applied to it to calculate sample TVC load. The initial calibration equation, which provides the conversion of measured TT values (hours) into TVC, was generated with pure Escherichia coli culture: log(CFU/g) = 8.30–0.60 *TT 25 ° for signal threshold of 25 degrees phase. Another calibration equation, which provides a better representation of whole food microbiota, was generated with a panel of 90 different food samples: log(CFU/g) = 8.53–0.60 *TT 25 °. This simple sensor system shows good correlation with traditional plate counting TVC method (ISO 4833) and suitability for autonomous on-site or in-field operation. Time to result of 1–6 h provided by the sensor sachet system is more than seven time faster than for the standard method. [Display omitted] • A sensor system for rapid microbiological testing of food samples. • It uses disposable sealable sachets with O2 sensors. • It provides rapid and simple detection and enumeration of total viable counts in food. • Results are produced in 1-8 h vs 48-72 h for standard TVC test. [ABSTRACT FROM AUTHOR]

Abstract Stricter effluent limits, water shortage conditions, land availability requires today even more the needs of advanced wastewater treatments. Attractive solutions come from membrane bioreactors (MBR), Integrated Fixed Film Activated Sludge (IFAS) or combinations (i.e., IFAS-MBRs). One crucial aspect for the applicability of this overall new technology, compared to the conventional activated sludge systems, is the lack of knowledge for design and manage (e.g., kinetic constants, optimal operative conditions etc.). In view of the above frame, the aim of the present study was to assess the kinetic and stoichiometric parameters of bacterial species in MBRs by means of respirometric techniques. Plant configurations, operational conditions and wastewater features (domestic/industrial) were analysed. Four different MBR plants were investigated: i) sequencing batch MBR subjected to a gradual salinity increase; ii) pre-denitrification MBR treating saline wastewater contaminated by hydrocarbons; iii) University of Cape Town (UCT) MBR treating domestic wastewater subjected to a carbon-to-nitrogen (C/N) ratio variation; iiii) UCT- IFAS -MBR treating domestic wastewater. Results show a significant influence on biomass respiratory activity from both plant configurations and operational conditions. The salinity increase severely affected the activity of autotrophic species, while heterotrophic community was mainly influenced by the C/N variation. Moreover, it was observed a specialization in the IFAS-MBR configuration, with the suspended biomass more affine to organic matter, whilst biofilm in the nitrification process. The respirometric analysis confirmed to be an effective tool for the evaluation of the biomass kinetic and stoichiometric parameters. The results of this study can be useful for the application of mathematical models in the design phase and for the monitoring of biomass viability during plant operations. Graphical abstract Image 1 Highlights • The study aim was to provide new insights on biokinetic behaviour of MBRs. • Respirometry was used to assess the kinetic and stoichiometric coefficients. • Heterotrophs highly suffered low C/N ratio with increased membrane fouling. • Salinity highly affected the autotrophic activity increasing the pore blocking. • It was observed a specialization of suspended and attached biomass in the IFAS-MBR. [ABSTRACT FROM AUTHOR]

A novel bench-scale stirred bioreactor for solid-state fermentation was used to determine the effect of the stirring rate on growth and enzymes production by Trichoderma harzianum PBLA. Lab-scale static tubular bioreactors were first used to assess the effect of bioreactor diameter on heat accumulation, growth, and production of cellulases and xylanases. The increased diameters (1.8–4.2 cm) led to increases in temperature up to 36 °C (at a rate of 1.08 °C/cm), which negatively affected the growth and enzyme production. Afterward, in the bench-scale bioreactor operated at rates up to 3.0 rpm, maximum xylanases production (107 ± 0.3 U/g dm) was attained at rates of 0.5 and 1.0 rpm, reaching a maximum of 34 ± 0.3 °C. Cellulases production was reduced (up to 79%) due to stirring. Therefore, the production of xylanases by T. harzianum can be performed in this cross-flow stirred SSF bioreactor at rates up to 1.0 rpm, avoiding heat accumulation and damage on metabolic activity. [ABSTRACT FROM AUTHOR]

Abstract Objective Islets from the same pancreas show remarkable variability in glucose sensitivity. While mitochondrial respiration is essential for glucose-stimulated insulin secretion, little is known regarding heterogeneity in mitochondrial function at the individual islet level. This is due in part to a lack of high-throughput and non-invasive methods for detecting single islet function. Methods We have developed a novel non-invasive, high-throughput methodology capable of assessing mitochondrial respiration in large-sized individual islets using the XF96 analyzer (Agilent Technologies). Results By increasing measurement sensitivity, we have reduced the minimal size of mouse and human islets needed to assess mitochondrial respiration to single large islets of >35,000 μm2 area (∼210 μm diameter). In addition, we have measured heterogeneous glucose-stimulated mitochondrial respiration among individual human and mouse islets from the same pancreas, allowing population analyses of islet mitochondrial function for the first time. Conclusions We have developed a novel methodology capable of analyzing mitochondrial function in large-sized individual islets. By highlighting islet functional heterogeneity, we hope this methodology can significantly advance islet research. Highlights • Islets from the same pancreas show remarkable variability in glucose sensitivity. • Little is known about heterogeneity in mitochondrial respiration in individual islets. • We developed a novel high-throughput method to measure individual islet function. • Individual islets within a population show heterogeneous glucose-stimulated respiration. • Our method may advance islet research by enabling populational metabolic profiling. [ABSTRACT FROM AUTHOR]

Autotrophic growth and decay rates of ammonium and nitrite oxidizing bacteria (AOB and NOB, respectively) have a significant impact on the design and on the process performance of wastewater treatment systems where nitrification occurs. Literature data on the separate decay rates of AOB and NOB is scarce and inconsistent. In this study, batch experiments based on respirometric techniques were conducted to determine the NOB decay rates under different oxidation-reduction potential conditions, in order to widen the understanding of nitrite dynamics. The decay rate measured under anoxic conditions was 85% lower than under aerobic conditions, whereas under anaerobic conditions the decay rate reduction was 92%. A design and simulation tool was used to assess the impact of applying these results in differentiated areas of an activated sludge system. Simulations show a greater impact for systems with a sludge retention time under 10 days, for which up to a 16-fold increase in NOB biomass concentration and up to 86% and 80% reductions in ammonium and nitrite concentrations in the effluent were calculated. Therefore, this work demonstrates that considering different decay rates for autotrophic biomass under different ORP conditions avoids underestimating system performance and over dimensioning new activated sludge schemes. [ABSTRACT FROM AUTHOR]

Environmental factors add constraints to organismal performance at their extremes, but support optimal performance at energetically beneficial conditions. In aquatic environments, salinity adds costs for ion transportation to the energetic budgets of osmoregulating animals, such as teleost fishes. These additional costs may limit the available energy for important ecological traits of fishes, including maximal and optimal swimming performance, which are required for successful foraging and migration in the wild. Here, we hypothesize that swimming performance, and its related costs, will be optimized at near-isoosmotic salinity, and decline under more saline conditions. Using the euryhaline shiner perch ( Cymatogaster aggregata ) as a model for coastal fishes, we determined critical swimming speeds and oxygen consumption rates during swimming at salinities of 12 g kg −1 (near-isoosmotic, brackish, S12) and 31 g kg −1 (hyperosmotic, marine, S31). Most tested metrics were unaffected by salinity, including aerobic scope, active metabolic rate and optimal swimming speed. Likewise, critical swimming speed (in body lengths per second, BL s −1 ) was not significantly different between fishes acclimated to S12 (4.8 ± 0.6 BL s −1 ) or S31 (5.1 ± 0.5 BL s −1 , means ± SD, n  = 5) suggesting that the fish could swim and hunt for prey equally well regardless of salinity. However, S31 conditions did cause comparatively higher oxygen consumption rates at swimming speeds from 0.5 to 1.5 BL s −1 , and a 20% increase in the extrapolated standard metabolic rate (i.e. cost of maintaining bodily functions). Our results confirm that there is an added energetic cost of salinity, but highlight that the cost of osmoregulation appears minimal relative to the energetic demands of swimming, and consequently has no effect on the maximal swimming performance of adult shiner perch. Given the strong salinity gradients naturally encountered in many coastal ecosystems, these data provide an explanation for the capacity of a coastal roaming species to move in an out of coastal habitat zones without significantly compromising their ability to hunt prey, avoid predation and migrate. As climate change locally affects environmental salinity, our results offer valuable insight towards the effects of environmental perturbations on fishes in coastal marine and estuarine habitats. [ABSTRACT FROM AUTHOR]

Dynamic environmental thermal conditions are known to affect physiological processes in ectothermic organisms that may influence movement, distribution and energetic costs. A better understanding of their metabolic Q 10 , temperature sensitivity, is needed in order to make realistic predictions about how some nearshore populations may respond to changing oceanographic conditions. Oxygen consumption was used as a proxy to measure acclimated standard metabolic rates (SMR) of the California horn shark ( Heterodontus francisci ) at four temperatures (14°, 16°, 20° and 22 °C) typically experienced throughout an annual cycle. Sharks were acclimated in a large holding tank at each of the desired temperatures for at least two weeks prior to the trial. All individuals tested were juveniles, ranging in size from 37 to 48 cm TL and weights of 0.41–0.94 kg. Respirometry trials ranged in length from 6 to 14 h. The estimated (±SE) resting Ṁ O 2 (mg O 2 kg −1  h −1 ) of the CA horn shark at each temperature treatment was 30.6 ± 3.4 (14°, n  = 4), 33.9 ± 2.3 (16°, n  = 10), 44.9 ± 2.4 (20°; n  = 9) and 57.9 ± 2.7 (22 °C; n  = 3). The metabolic Q 10 of the CA horn shark from 14° to 22 °C is 2.01, providing a metric to generate predictive models to estimate minimum metabolic costs associated with changing thermal regimes and global sea temperature rise. Predictions from our model indicate during years 2012 to 2016, rising sea surface temperature associated with a strong El Niño Southern Oscillation (ENSO) event resulted in a 23% increase in minimum metabolic costs for the CA horn shark. The results from our model suggest the CA horn shark may need to adapt compensatory behaviors (e.g., behavioral thermoregulation) to cope with ENSO events and climate change. [ABSTRACT FROM AUTHOR]

Round goby ( Neogobius melanostomus ) and western tubenose goby ( Proterorhinus semilunaris ) invaded the Laurentian Great Lakes at approximately the same time and area yet have shown substantial differences in their post-invasion success with more rapid establishment and development of much larger abundances of round goby populations throughout the invaded habitat. In this study, we compared differences in physiological performance (thermal tolerance and standard metabolic rate) between round and tubenose goby collected from the Huron-Erie corridor. Tubenose goby were observed to have lower thermal tolerance but exhibited similar standard metabolic rate across environmental temperatures compared to round goby. At temperatures exceeding 31 °C, tubenose goby demonstrated significantly higher mortalities and shorter times to death relative to round goby. The observed differences in thermal tolerance were consistent with differences in the native geographic ranges observed for each species at their southern ranges. The observed differences in physiological performance combined with species differences in other life history traits such body size, reproduction, feeding ecology and habitat affiliation may also explain differences in the invasiveness experienced by these two Great Lakes invasive fish including a greater ability of round gobies to occupy extreme habitats with large water temperature fluctuations. [ABSTRACT FROM AUTHOR]

In this study, the monitoring of reactive oxygen species and the regeneration of the ferrous ions catalyst were performed during electro-Fenton (EF) process to highlight the influence of operating parameters. The removal of metronidazole (MTZ) was implemented in an electrochemical mono-compartment batch reactor under various ranges of current densities, initial MTZ and ferrous ions concentrations, and pH values. It was found that under 0.07 mA cm −2 , 0.1 mM of ferrous ions and pH = 3, the efficiency of 100 mg L −1 MTZ degradation and mineralization were 100% within 20 min and 40% within 135 min of electrolysis, respectively. The highest hydrogen peroxide and hydroxyl radical concentrations, 1.4 mM and 2.28 mM respectively, were obtained at 60 min electrolysis at 0.07 mA cm −2 . Improvement of the biodegradability was reached from 60 min of electrolysis with a BOD 5 /COD ratio above 0.4, which was reinforced by a respirometric study, that supports the feasibility of coupling electro-Fenton and biological treatment for the metronidazole removal. [ABSTRACT FROM AUTHOR]

Across a wide range of taxa, individuals within populations exhibit alternative life history strategies (ALHS) where their phenotypes dramatically differ due to divergent investments in growth, reproduction and survivorship, with the resulting trade-offs directly impacting Darwinian fitness. Though the maintenance of ALHS within populations is fairly well understood, little is known regarding the physiological mechanisms that underlie ALHS and how environmental conditions can affect the evolution and expression of these phenotypes. One such ALHS, known as Alba, exists within females of many species in the butterfly genus Colias . Previous works in New World species not only found that female morphs differ in their wing color due to a reallocation of resources away from the synthesis of wing pigments to other areas of development, but also that temperature played an important role in these trade-offs. Here we build on previous work conducted in New World species by measuring life history traits and conducting lipidomics on individuals reared at hot and cold temperatures in the Old World species Colias croceus . Results suggest that the fitness of Alba and orange morphs likely varies with rearing temperature, where Alba females have higher fitness in cold conditions and orange in warm. Additionally shared traits between Old and New World species suggest the Alba mechanism is likely conserved across the genus. Finally, in the cold treatment we observe an intermediate yellow morph that may have decreased fitness due to slower larval development. This cost may manifest as disruptive selection in the field, thereby favoring the maintenance of the two discrete morphs. Taken together these results add insights into the evolution of, and the selection on, the Alba ALHS. [ABSTRACT FROM AUTHOR]

Chemical industry wastewater is known to have disproportionate nutrient concentrations with varying C:N ratios, thereby individually affecting the growth of heterotrophs and autotrophs in activated sludge. The present study underlines the impact of the changing availability of organic and inorganic carbon on the ratio of nitrifying biomass in an industrial activated sludge. To quantify changes, oxygen uptake rates by nitrifiers were monitored using respirometry, while nitrifier abundance was determined by real-time PCR using 16S rRNA primers. The obtained results point to the prominent influence of the organic or inorganic carbon source, reducing or increasing the active nitrifying biomass ratio and AOB gene quantity respectively. When the active nitrifier ratio dropped below 10% of the total activity or when nitrifiers were limited for inorganic carbon, ammonia oxidation was compromised. Nitrifiers were able to recover sufficient activity after a carbon starvation period of 34 days through the supply of gaseous CO 2 or bicarbonate. The results of this study suggest a superior role of gaseous CO 2 over bicarbonate as carbon source for nitrifiers and the feasibility to operate a high performing nitrification without any COD. [ABSTRACT FROM AUTHOR]

Objective Energy metabolism is challenged upon nutrient stress, eventually leading to a variety of metabolic diseases that represent a major global health burden. Methods Here, we combine quantitative mitochondrial respirometry (Seahorse technology) and proteomics (LC-MS/MS-based total protein approach) to understand how molecular changes translate to changes in mitochondrial energy transduction during diet-induced obesity (DIO) in the liver. Results The integrative analysis reveals that significantly increased palmitoyl-carnitine respiration is supported by an array of proteins enriching lipid metabolism pathways. Upstream of the respiratory chain, the increased capacity for ATP synthesis during DIO associates strongest to mitochondrial uptake of pyruvate, which is routed towards carboxylation. At the respiratory chain, robust increases of complex I are uncovered by cumulative analysis of single subunit concentrations. Specifically, nuclear-encoded accessory subunits, but not mitochondrial-encoded or core units, appear to be permissive for enhanced lipid oxidation. Conclusion Our integrative analysis, that we dubbed “respiromics”, represents an effective tool to link molecular changes to functional mechanisms in liver energy metabolism, and, more generally, can be applied for mitochondrial analysis in a variety of metabolic and mitochondrial disease models. [ABSTRACT FROM AUTHOR]