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Acclimation to hypoxia and anoxia is important in various ecological systems, especially flooded soil. Phyllostachys pracecox is sensitive to flooding, and therefore, it is important to explore ways of alleviating hypoxia stress in the roots. In this study, we investigated the regulatory effect of spermidine (Spd) on flooded P. praecox seedlings.A batch experiment was carried out in roots treated with Spd under flooding for eight days. The following factors were subsequently measured: growth, survival rate, root respiratory activity, soluble protein and anaerobic respiration enzyme contents (pyruvate decarboxylase, PDC; alcohol dehydrogenase, ADH; lactate dehydrogenase, LDH; alanine aminotransferase, AlaAT), S-adenosylmethionine decarboxylase (SAMDC), nitrate reductase (NR), ACC oxidase (ACO) and ACC synthetase (ACS) activities, free Spd, spermine (Spm) and the diamine precursor putrescine (Put) content, indole-3-acetic acid (IAA) and abscisic acid (ABA) content, ethylene emissions and expression of hormone-related genes.Application of Spd promoted root growth (root length, volume, surface and dry weight) and root respiratory inhibition, improved the soluble protein content, and reduced the OThese results suggest that Spd regulated hormone concentrations, the content of Spd, Spm and Put, and related gene expression, in turn regulating physiological changes such as anaerobic enzyme activity, mitigating flooding stress in the roots and improving overall growth. Spd therefore has the potential to improve the adaptability of P. praecox to flooding stress.

The transcript levels of the phytoglobin (Pgb) genes Pgb1 and Pgb3, and the protein content of Pgb1 were responsive to anaerobiosis in several tissues of barley (Hordeum vulgare L.). Oxygen deficiency induced the level of both Pgb transcripts and protein in aleurone layers and coleoptiles, as well as up-regulated both Pgb1 and Pgb3 in leaves, apexes and more strongly in roots of barley seedlings. In O

Syntrophic acetate oxidation (SAO) coupled with hydrogenotrophic methanogenesis (HM) plays a vital role in the anaerobic digestion of protein-rich feedstocks such as food wastes. However, current knowledge of the biodiversity and genetic potential of the involved microbial participants, especially syntrophic acetate-oxidizing bacteria (SAOB), is limited due to the low abundance of these microorganisms and challenges in their isolation. The intent of this study was to enrich and identify potential SAOB. Therefore, we conducted continuous acetate feeding under high ammonia concentrations using two separate inoculum consortia of microorganisms that originated from full-scale mesophilic food waste digesters, which lasted for more than 200 days. Using 16S rRNA gene amplicon and metagenomic analyses, we observed a convergence of the experimental microbial communities during the enrichment regarding taxonomic composition and metabolic functional composition. Stable carbon isotope analyses of biogas indicated that SAO-HM was the dominant methanogenic pathway during the enrichment process. The hydrogenotrophic methanogen

The greenhouse gas methane (CH4) is of pivotal importance for Earth’s climate system and as a human energy source. A significant fraction of this CH4 is produced by anaerobic Archaea. Here, we describe the first CH4 production by facultative anaerobic wood-rot fungi during growth on hydroxylated/carboxylated aromatic compounds, including lignin and lignite. The amount of CH4 produced by fungi is positively correlated with the amount of CH3Cl produced during the rapid growth period of the fungus. Biochemical, genetic, and stable isotopic tracer analyses reveal the existence of a novel halomethane-dependent fungal CH4 production pathway during the degradation of phenol and benzoic acid monomers and polymers and utilization of cyclic sugars. Even though this halomethane-dependent pathway may only play a side role in anaerobic fungal activity, it could represent a globally significant, previously overlooked source of biogenic CH4 in natural ecosystems. IMPORTANCE Here, we demonstrate that wood-rot fungi produce methane anaerobically without the involvement of methanogenic archaea via a new, halomethane-dependent pathway. These findings of an anaerobic fungal methane formation pathway open another avenue in methane research and will further assist with current efforts in the identification of the processes involved and their ecological implications., Microbiology Spectrum, 10 (5), ISSN:2165-0497

We recently described a new member of the CRP (cyclic AMP receptor protein)/FNR (fumarate and nitrate reductase regulatory protein) family called RedB, an acronym for redox brake, that functions to limit the production of ATP and NADH. This study shows that the RedB regulon significantly overlaps the FnrL regulon, with 199 genes being either directly or indirectly regulated by both of these global regulatory proteins. Among these 199 coregulated genes, 192 are divergently regulated, indicating that RedB functions as an antagonist of FnrL. Chromatin immunoprecipitation sequencing (ChIP-seq) analysis indicates that RedB and Fnr directly coregulate only 4 out of 199 genes. The primary mechanism for the divergent regulation of target genes thus involves indirect regulation by both RedB and FnrL (156 cases). Additional regulation involves direct binding by RedB and indirect regulation by FnrL (36 cases) or direct binding by FnrL and indirect regulation by RedB (3 cases). Analysis of physiological pathways under direct and indirect control by these global regulators demonstrates that RedB functions primarily to limit energy production, while FnrL functions to enhance energy production. This regulation includes glycolysis, gluconeogenesis, photosynthesis, hydrogen oxidation, electron transport, carbon fixation, lipid biosynthesis, and protein synthesis. Finally, we show that 75% of genomes from diverse species that code for RedB proteins also harbor genes coding for FNR homologs. This cooccurrence indicates that RedB likely has an important role in buffering FNR-mediated energy production in a broad range of species.

Imbalances of soil available nutrients and soilborne diseases have seriously restricted the productivity of crops and jeopardized food security worldwide. Pyrroloquinoline quinone (PQQ), a redox cofactor in some bacteria involved in glucose metabolism and phosphorus mineralization, could be anticipated to alter soil ecosystems to a certain extent. However, there is limited information on PQQ defending soilborne pathogens and regulating soil main nutrients. Here, a pot experiment based on mono-cropping soils of pepper was conducted to examine the effects of PQQ amendment on reconstructing soil microbial communities and soil nutrients under aerobic/anaerobic conditions comprising three treatments, namely, control, PQQ (aerobic), and FL-PQQ (anaerobic). The results revealed that soil microbial community composition and soil nutrients were distinctly altered by PQQ regimes. Compared to control, PQQ treatment significantly increased the content of soil available phosphorus (AP), while FL_PQQ treatment strongly improved the content of soil available nitrogen (AN). In terms of pathogens, relative to control, both PQQ treatments suppressed the abundances of pathogens, of which FL_PQQ treatment significantly decreased the abundance of the pathotrophic fungal by 64% and the abundance of Fusarium oxysporum by 57%, largely attributed to the increase of organic acid generators (O

Novel bacterial isolates with the capabilities of lignin depolymerization, catabolism, or both, could be pertinent to lignocellulosic biofuel applications. In this study, we aimed to identify anaerobic bacteria that could address the economic challenges faced with microbial-mediated biotechnologies, such as the need for aeration and mixing. Using a consortium seeded from temperate forest soil and enriched under anoxic conditions with organosolv lignin as the sole carbon source, we successfully isolated a novel bacterium, designated 159R. Based on the 16S rRNA gene, the isolate belongs to the genus Sodalis in the family Bruguierivoracaceae. Whole-genome sequencing revealed a genome size of 6.38 Mbp and a GC content of 55 mol%. To resolve the phylogenetic position of 159R, its phylogeny was reconstructed using (i) 16S rRNA genes of its closest relatives, (ii) multilocus sequence analysis (MLSA) of 100 genes, (iii) 49 clusters of orthologous groups (COG) domains, and (iv) 400 conserved proteins. Isolate 159R was closely related to the deadwood associated Sodalis guild rather than the tsetse fly and other insect endosymbiont guilds. Estimated genome-sequence-based digital DNA-DNA hybridization (dDDH), genome percentage of conserved proteins (POCP), and an alignment analysis between 159R and the Sodalis clade species further supported that isolate 159R was part of the Sodalis genus and a strain of Sodalis ligni. We proposed the name Sodalis ligni str. 159R (=DSM 110549 = ATCC TSD-177). IMPORTANCE Currently, in the paper industry, paper mill pulping relies on unsustainable and costly processes to remove lignin from lignocellulosic material. A greener approach is biopulping, which uses microbes and their enzymes to break down lignin. However, there are limitations to biopulping that prevent it from outcompeting other pulping processes, such as requiring constant aeration and mixing. Anaerobic bacteria are a promising alternative source for consolidated depolymerization of lignin and its conversion to valuable by-products. We presented Sodalis ligni str. 159R and its characteristics as another example of potential mechanisms that can be developed for lignocellulosic applications.

This study aimed to examine the effect of circadian rhythms (CR) on anaerobic performance and subsequent recovery, muscle damage, and respiratory muscle strength. Twenty diurnally active male football players (age, 22.20 ± 3.14 y) were asked to perform the Wingate anaerobic power test three times for 30 s each at 09:00, 14:00 and 19:00 h, with a minimum recovery period of 1 week between each testing day. Pretest oral temperature, respiratory muscle strength, oxygen saturation, and rating of perceived exertion were recorded at three different time of the day. To examine post-exercise recovery, heart rate (HR) and lactic acid (LA) levels were recorded before and after the tests. Blood samples were collected 20 min after each test to assess muscle damage. The body temperature taken at 19:00 h was the highest of the three (

AIM To examine the effects of administration of monophasic oral contraceptive (OC) on the body composition and aerobic and anaerobic capacities of female athletes. METHODS Ten female athletes (23.0 ± 4.1 years old) participated in this study. All the subjects were examined during the menstrual cycle (early follicular [EF], middle luteal [ML]) and OC cycle (inactive OC, and active OC phases). After the menstrual cycle measurements, all the subjects began taking OC. The athletes tested using a body composition, circumferences, the lactate curve test, the maximal oxygen consumption test, and the Wingate test during all phases. RESULTS Waist circumference was lower during the OC cycle than menstrual cycle (P

Naked mole-rats are among the mammalian champions of hypoxia tolerance. They evolved adaptations centered around reducing metabolic rate to overcome the challenges experienced in their underground burrows. In this study, we used next-generation sequencing to investigate one of the factors likely supporting hypoxia tolerance in naked mole-rat brains, posttranscriptional microRNAs (miRNAs). Of the 212 conserved miRNAs identified using small RNA sequencing, 18 displayed significant differential expression during hypoxia. Bioinformatic enrichment revealed that hypoxia-mediated miRNAs were suppressing energy expensive processes including de novo protein translation and cellular proliferation. This suppression occurred alongside the activation of neuroprotective and neuroinflammatory pathways, and the induction of central signal transduction pathways including HIF-1α and NFκB via miR-335, miR-101, and miR-155. MiRNAs also coordinated anaerobic glycolytic fuel sources, where hypoxia-upregulated miR-365 likely suppressed protein levels of ketohexokinase, the enzyme responsible for catalyzing the first committed step of fructose catabolism. This was further supported by a hypoxia-mediated reduction in glucose transporter 5 proteins that import fructose into the cell. Yet, messenger RNA and protein levels of lactate dehydrogenase, which converts pyruvate to lactate in the absence of oxygen, were elevated during hypoxia. Together, this demonstrated the induction of anaerobic glycolysis despite a lack of reliance on fructose as the primary fuel source, suggesting that hypoxic brains are metabolically different than anoxic naked mole-rat brains that were previously found to shift to fructose-based glycolysis. Our findings contribute to the growing body of oxygen-responsive miRNAs "OxymiRs" that facilitate natural miRNA-mediated mechanisms for successful hypoxic exposures.

Thermophilic solid-state anaerobic digestion (SS-AD) of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, was carried out in this study. The effects of temperature (40-60°C), initial solid content (ISC, 17.5-32.5%), and C/N ratio (15-32 : 1) on biogas production were evaluated using a Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). The results showed that optimization of process parameters is important to promote the SS-AD performance. All the factors, including interactive terms (except the ISC), were significant in the quadratic model for biogas production with SS-AD. Among the three operation parameters, the C/N ratio had the largest effect on biogas production, followed by temperature, and a maximum biogas yield of 241.4 mL gVS-1 could be achieved at 47.3°C, ISC = 24.81 % , and C / N = 22.35 . After 20 d of SS-AD, the microbial community structure under different conditions was characterized by high-throughput sequencing, showing that Firmicutes, Bacteroidetes, Chloroflexi, Synergistetes, and Proteobacteria dominated the bacterial community, and that Firmicutes had a competitive advantage over Bacteroidetes at elevated temperatures. The biogas production values and relative abundance of OPB54 and Bacteroidia after 20 d of SS-AD can be fitted well using a quadratic model, implying that OPB54 and Bacteroidia play important roles in the methanogenic metabolism for agricultural waste thermophilic SS-AD.

Reproductively mature koi carps (Cyprinus carpio) showed a prominent diurnal variation of sex steroids with sustained nocturnal rise. Exposure to chronic hypoxia (DO

Rhodopseudomonas palustris CGA009 (R. palustris) is a gram negative purple non-sulfur bacteria that grows phototrophically or chemotrophically by fixing or catabolizing a wide array of substrates including lignin breakdown products (e.g., p-coumarate) for its carbon and nitrogen requirements. It can grow aerobically or anaerobically and can use light, inorganic, and organic compounds for energy production. Due to its ability to convert different carbon sources into useful products in anaerobic mode, this study, for the first time, reconstructed a metabolic and expression (ME-) model of R. palustris to investigate its anaerobic-photoheterotrophic growth. Unlike metabolic (M-) models, ME-models include transcription and translation reactions along with macromolecules synthesis and couple these reactions with growth rate. This unique feature of the ME-model led to nonlinear growth curve predictions which matched closely with experimental growth rate data. At the theoretical maximum growth rate, the ME-model suggested a diminishing rate of carbon fixation and predicted malate dehydrogenase and glycerol-3 phosphate dehydrogenase as alternate electron sinks. Moreover, the ME-model also identified ferredoxin as a key regulator in distributing electrons between major redox balancing pathways. Since ME-models include turnover rate for each metabolic reaction, it was used to successfully capture experimentally observed temperature regulation of different nitrogenases. Overall, these unique features of the ME-model demonstrated the influence of nitrogenases and rubiscos on R. palustris growth and predicted a key regulator in distributing electrons between major redox balancing pathways, thus establishing a platform for in silico investigation of R. palustris metabolism from a multi-omics perspective.IMPORTANCEIn this work, we reconstructed the first ME-model for a purple non-sulfur bacterium (PNSB). Using the ME-model, different aspects of R. palustris metabolism were examined. First, the ME-model was used to analyze how reducing power entering the R. palustris cell through organic carbon sources gets partitioned into biomass, carbon dioxide fixation, and nitrogen fixation. Furthermore, the ME-model predicted electron flux through ferredoxin as a major bottleneck in distributing electrons to nitrogenase enzymes. Next, the ME-model characterized different nitrogenase enzymes and successfully recapitulated experimentally observed temperature regulations of those enzymes. Identifying the bottleneck responsible for transferring electron to nitrogenase enzymes and recapitulating the temperature regulation of different nitrogenase enzymes can have profound implications in metabolic engineering, such as hydrogen production from R. palustris. Another interesting application of this ME-model can be to take advantage of its redox balancing strategy to gain understanding on regulatory mechanism of biodegradable plastic production precursors, such as polyhydroxybutyrate (PHB).

Indoor stadium is an important place for physical exercise and sports practice, but few studies have considered the impact of indoor environment on exercise performance. Anaerobic exercise refers to exercise with high load intensity and instantaneous intensity. Many kinds of exercise performance are closely related to anaerobic exercise. Therefore, the purpose of this study was to examine the influence of temperature, relative humidity and CO

Purpose To compare the anaerobic work capacity (AnWC, i.e., attributable anaerobic mechanical work) assessed using four different approaches/models applied to time-trial (TT) cycle-ergometry exercise. Methods Fifteen male cyclists completed a 7 × 4-min submaximal protocol and a 3-min all-out TT (TTAO). Linear relationships between power output (PO) and submaximal metabolic rate were constructed to estimate TT-specific gross efficiency (GE) and AnWC, using either a measured resting metabolic rate as a Y-intercept (7 + YLIN) or no measured Y-intercept (7-YLIN). In addition, GE of the last submaximal bout (GELAST) was used to estimate AnWC, and critical power (CP) from TTAO (CP3´AO) was used to estimate mechanical work above CP (W’, i.e., “AnWC”). Results Average PO during TTAO was 5.43 ± 0.30 and CP was 4.48 ± 0.23 W∙kg−1. The TT-associated GE values were ~ 22.0% for both 7 + YLIN and 7-YLIN and ~ 21.1% for GELAST (both P −1 for the 7 + YLIN, 7-YLIN, GELAST, and CP3´AO models, respectively (7 + YLIN and 7-YLIN versus GELAST, both P LIN, 7-YLIN, and GELAST versus CP3´AO, all P LIN, 7-YLIN, and GELAST, typical errors in AnWC values ranged from 7 to 11 J∙kg−1, whereas 7 + YLIN, 7-YLIN, and GELAST versus CP3´AO revealed typical errors of 55–59 J∙kg−1. Conclusion These findings demonstrate a substantial disagreement in AnWC between CP3´AO and the other models. The 7 + YLIN and 7-YLIN generated 10% lower AnWC values than the GELAST model, whereas 7 + YLIN and 7-YLIN generated similar values of AnWC.

This study investigated the 30-days altitude training (2500 m, LHTH-live and training high) on hematological responses and aerobic–anaerobic performances parameters of high-level Paralympic athletes. Aerobic capacity was assessed by 3000 m run, and anaerobic variables (velocity, force and mechanical power) by a maximal 30-s semi-tethered running test (AO30). These assessments were carried out at low altitude before (PRE) and after LHTH (5–6 and 15–16 days, POST1 and POST2, respectively). During LHTH, hematological analyzes were performed on days 1, 12, 20 and 30. After LHTH, aerobic performance decreased 1.7% in POST1, but showed an amazing increase in POST2 (15.4 s reduction in the 3000 m test, 2.8%). Regarding anaerobic parameters, athletes showed a reduction in velocity, force and power in POST1, but velocity and power returned to their initial conditions in POST2. In addition, all participants had higher hemoglobin (Hb) values at the end of LHTH (30 days), but at POST2 these results were close to those of PRE. The centrality metrics obtained by complex networks (pondered degree, pagerank and betweenness) in the PRE and POST2 scenarios highlighted hemoglobin, hematocrit (Hct) and minimum force, velocity and power, suggesting these variables on the way to increasing endurance performance. The Jaccard’s distance metrics showed dissimilarity between the PRE and POST2 graphs, and Hb and Hct as more prominent nodes for all centrality metrics. These results indicate that adaptive process from LHTH was highlighted by the complex networks, which can help understanding the better aerobic performance at low altitude after 16 days in Paralympic athletes.

The current study evaluated the effects of nano delivery of Spirulina platensis on growth performance, digestive enzymes, and biochemical, immunological, and antioxidative status, as well as resistance to Aeromonas veronii and some physical stressor challenges in Nile tilapia, Oreochromis niloticus. Three experimental fish groups (n = 270) with mean weights of 26 ± 0.30 g and mean lengths of 10 ± 0.5 cm were used; the first additive-free basal diet served as the control group, whereas the following two groups were supplemented with spirulina nanoparticles (SPNP) at 0 (control), 0.25, and 0.5%/kg diet for 4 weeks. Following the feeding trial, fish were challenged with hypoxia, cold stresses, and pathogenic bacteria (A. veronii) infection (9 × 108 CFU/ml). SPNP supplementation, especially 0.5%, (p 0.25% SPNP > 0% SPNP compared with the control. Protection in the incorporated fish groups exposed to A. veronii was 100% compared with the control group, which showed 50% cumulative mortalities. In conclusion, dietary SPNP supplementation improved growth performance, antioxidant activity, immune response, digestive enzymes, related gene expression, and resistance of Nile Tilapia to hypoxia, cold, and A. veronii infection. Thus, SPNP could be used as a natural therapy for controlling those stressors.

Anaerobic ceramic membrane bioreactor (AnCMBR) is an attractive alternative for the treatment of high-strength phenol wastewater, but the effects of sludge retention time (SRT) on the performance and membrane fouling are still unclear. The results indicated that the AnCMBR was successfully employed to treat high-strength wastewater containing 5 g phenol L-1. The removal efficiencies of phenol and chemical oxygen demand (COD) reached over 99.5% and 99%, respectively, with long SRT and short SRT. SRT had no obvious effect on the performance of the AnCMBR treating high-strength phenol wastewater with long time operation. The strong performance robustness of AnCMBR benefited from the enrichment of hydrogenotrophic methanogens and syntrophic phenol-degrading bacteria. However, the decline of SRT led to a more severe membrane fouling in the AnCMBR, which was caused by the small size of sludge flocs and high concentration of protein in the biopolymers. Therefore, this work presented a comprehensive insight to the feasibility and robustness of the AnCMBR for treating high-strength phenol wastewater.

We isolated and characterized 65 anaerobic gut fungal (AGF; Neocallimastigomycota) strains from fecal samples of five wild (W, axis deer, white-tailed deer, Boer goat, mouflon, and Nilgiri tahr), one zoo-housed (Z, zebra), and three domesticated (D, horse, sheep, and goat) herbivores in the US states of Texas (TX) and Oklahoma (OK), Wales (WA), and the Indian states of Kerala (KE) and Haryana (HA). Phylogenetic assessment using the D1-D2 regions of the large subunit (28S) rDNA and internal transcribed spacer 1 (ITS1) identified seven monophyletic clades that are distinct from all currently recognized AGF genera. All strains displayed monocentric thalli and produced exclusively or predominantly monoflagellate zoospores, with the exception of axis deer strains, which produced polyflagellate zoospores. Analysis of amplicon-based AGF diversity surveys indicated that zebra and horse strains are representatives of uncultured AL1 group, whereas domesticated goat and sheep strains are representatives of uncultured AL5 group, previously encountered in fecal and rumen samples of multiple herbivores. The other five lineages, all of which were isolated from wild herbivores, have not been previously encountered in such surveys. Our results significantly expand the genus-level diversity within the Neocallimastigomycota and strongly suggest that wild herbivores represent a yet-untapped reservoir of AGF diversity. We propose seven novel genera and eight novel Neocallimastigomycota species to comprise these strains, for which we propose the names

Made available in DSpace on 2022-05-01T10:18:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 We used measurements of metabolic perturbation obtained after sparring to estimate energetics contribution during no-gi Brazilian jiu-jitsu. Ten advanced grapplers performed two six-minute sparring bouts separated by 24 hours. Kinetics of recovery rate of oxygen uptake was modelled and post-combat-sparring blood-lactate concentration measured to estimate oxygen equivalents for phospholytic and glycolytic components of anaerobic energetics, respectively. Linear regression was used to estimate end-combat-sparring rate of oxygen uptake. Regional and whole-body composition were assessed using dual X-ray absorptiometry with associations between these measurements and energy turnover explored using Pearson’s correlation coefficient (significance, P < 0.05). Estimated oxygen equivalents for phospholytic and glycolytic contributions to anaerobic metabolism were 16.9 ± 8.4 (~28%) and 44.6 ± 13.5 (~72%) mLkg-1, respectively. Estimated end-exercise rate of oxygen uptake was 44.2 ± 7.0 mLkg-1min-1. Trunk lean mass was positively correlated with both total anaerobic and glycolytic-specific energetics (total, R = 0.645, p = 0.044; glycolytic, R = 0.692, p = 0.027) and negatively correlated with end-exercise rate of oxygen uptake (R = -0.650, p = 0.042). There were no correlations for any measurement of body composition and phospholytic-specific energetics. Six minutes of no-gi Brazilian jiu-jitsu sparring involves high relative contribution from the glycolytic component to total anaerobic energy provision and the link between this energetics profile and trunk lean mass is consistent with the predominance of ground-based combat that is unique for this combat sport. Training programs for Brazilian jiu-jitsu practitioners should be designed with consideration given to these specific energetics characteristics. Institute of Bioscience Graduate Program in Human Development and Technology São Paulo State University (UNESP) Department of Physical Education São Paulo State University (UNESP) Division of Endocrinology Diabetes and Bone Department of Medicine Icahn School of Medicine at Mount Sinai Institute of Bioscience Graduate Program in Human Development and Technology São Paulo State University (UNESP) Department of Physical Education São Paulo State University (UNESP)

Conspicuous egg-shaped, white, and smooth structures were observed at a hydrothermal vent site in the Guaymas Basin, Gulf of California. The gelatinous structures decomposed within hours after sampling. Scanning electron microscopy (SEM) and light microscopy showed that the structure consisted of filaments of less than 0.1 μm thickness, similar to those observed for “Candidatus Arcobacter sulfidicus.” SEM-energy-dispersive X-ray spectroscopy (EDS) showed that the filaments were sulfur rich. According to 16S rRNA gene amplicon and fluorescence in situ hybridization (FISH) analyses, Arcobacter, a sulfide oxidizer that is known to produce filamentous elemental sulfur, was among the dominant species in the structure and was likely responsible for its formation. Arcobacter normally produces woolly snowflake like structures in opposed gradients of sulfide and oxygen. In the laboratory, we observed sulfide consumption in the anoxic zone of the structure, suggesting an anaerobic conversion. The sulfide oxidation and decomposition of the structure in the laboratory may be explained by dissolution of the sulfur filaments by reaction with sulfide under formation of polysulfides. IMPORTANCE At the deep-sea Guaymas Basin hydrothermal vent system, sulfide-rich hydrothermal fluids mix with oxygenated seawater, thereby providing a habitat for microbial sulfur oxidation. Microbial sulfur oxidation in the deep sea involves a variety of organisms and processes and can result in the excretion of elemental sulfur. Here, we report on conspicuous white and smooth gelatinous structures found on hot vents. These strange egg-shaped structures were often observed on previous occasions in the Guaymas Basin, but their composition and formation process were unknown. Our data suggest that the notable and highly ephemeral structure was likely formed by the well-known sulfide-oxidizing Arcobacter. While normally Arcobacter produces loose flocs or woolly layers, here smooth gel-like structures were found.

An important and interesting feature of rice is that it can germinate under anoxic conditions. Though several biochemical adaptive mechanisms play an important role in the anaerobic germination of rice but the role of phytoglobin-nitric oxide cycle and alternative oxidase pathway is not known, therefore in this study we investigated the role of these pathways in anaerobic germination. Under anoxic conditions, deepwater rice germinated much higher and rapidly than aerobic condition and the anaerobic germination and growth were much higher in the presence of nitrite. The addition of nitrite stimulated NR activity and NO production. Important components of phytoglobin-NO cycle such as methaemoglobin reductase activity, expression of Phytoglobin1, NIA1 were elevated under anaerobic conditions in the presence of nitrite. The operation of phytoglobin-NO cycle also enhanced anaerobic ATP generation, LDH, ADH activities and in parallel ethylene levels were also enhanced. Interestingly nitrite suppressed the ROS production and lipid peroxidation. The reduction of ROS was accompanied by enhanced expression of mitochondrial alternative oxidase protein and its capacity. Application of AOX inhibitor SHAM inhibited the anoxic growth mediated by nitrite. In addition, nitrite improved the submergence tolerance of seedlings. Our study revealed that nitrite driven phytoglobin-NO cycle and AOX are crucial players in anaerobic germination and growth of deepwater rice.

Knowledge of the circadian rhythm of the blind person and diurnal changes in anaerobic power and hormones concentration can create the possibility of individualising physical training. The aim of the study was to examine the time-of-day effects on anaerobic performance and the concentration of selected hormones. The measurements were performed at two different times of the day (10:00 a.m., 10:00 p.m.) in blind men at the age of 20–25 years old. The experiment group was chosen by using repeated hormonal tests four times a day so that each selected patient had a sleep/wake cycle even of 24 h. Anaerobic peak power and total work were tested in an anaerobic sprint test, and the concentration of growth hormone, testosterone, cortisol, and melatonin was determined. In blind men, the hormonal response was not driven by the photoperiod as in the control group. In the blind group, at 10:00 p.m., anaerobic peak power and total work results were significantly higher than at 10:00 a.m. and negatively correlated with melatonin levels. No such correlation was found in the control group.

Staphylococcus aureus is associated with the development of persistent and severe inflammatory diseases of the upper airways. Yet, S. aureus is also carried asymptomatically in the sinonasal cavity of ∼50% of healthy adults. The causes of this duality and host and microbial factors that tip the balance between S. aureus pathogenesis and commensalism are poorly understood. We have shown that by degrading mucins, anaerobic microbiota support the growth of airway pathogens by liberating metabolites that are otherwise unavailable. Given the widely reported culture-based detection of anaerobes from individuals with chronic rhinosinusitis (CRS), here we tested our hypothesis that CRS microbiota is characterized by a mucin-degrading phenotype that alters S. aureus physiology. Using 16S rRNA gene sequencing, we indeed observed an increased prevalence and abundance of anaerobes in CRS relative to non-CRS controls. PICRUSt2-based functional predictions suggested increased mucin degradation potential among CRS microbiota that was confirmed by direct enrichment culture. Prevotella, Fusobacterium, and Streptococcus comprised a core mucin-degrading community across CRS subjects that generated a nutrient pool that augmented S. aureus growth on mucin as a carbon source. Finally, using transcriptome sequencing (RNA-seq), we observed that S. aureus transcription is profoundly altered in the presence of mucin-derived metabolites, though expression of several key metabolism- and virulence-associated pathways varied between CRS-derived bacterial communities. Together, these data support a model in which S. aureus metabolism and virulence in the upper airways are dependent upon the composition of cocolonizing microbiota and the metabolites they exchange.

Humans and animals with pulmonary hypertension (PH) show right ventricular (RV) capillary growth, which positively correlates with overall RV hypertrophy. However, molecular drivers of RV vascular augmentation in PH are unknown. Prolyl hydroxylase (PHD2) is a regulator of hypoxia-inducible factors (HIFs), which transcriptionally activates several proangiogenic genes, including the glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). We hypothesized that a signaling axis of PHD2-HIF1α-PFKFB3 contributes to adaptive coupling between the RV vasculature and tissue volume to maintain appropriate vascular density in PH. We used design-based stereology to analyze endothelial cell (EC) proliferation and the absolute length of the vascular network in the RV free wall, relative to the tissue volume in mice challenged with hypoxic PH. We observed increased RV EC proliferation starting after 6 h of hypoxia challenge. Using parabiotic mice, we found no evidence for a contribution of circulating EC precursors to the RV vascular network. Mice with transgenic deletion or pharmacological inhibition of PHD2, HIF1α, or PFKFB3 all had evidence of impaired RV vascular adaptation following hypoxia PH challenge. PHD2-HIF1α-PFKFB3 contributes to structural coupling between the RV vascular length and tissue volume in hypoxic mice, consistent with homeostatic mechanisms that maintain appropriate vascular density. Activating this pathway could help augment the RV vasculature and preserve RV substrate delivery in PH, as an approach to promote RV function.

Background Mitochondria and peroxisomes are the two organelles that are most affected during adaptation to microoxic or anoxic environments. Mitochondria are known to transform into anaerobic mitochondria, hydrogenosomes, mitosomes, and various transition stages in between, collectively called mitochondrion-related organelles (MROs), which vary in enzymatic capacity. Anaerobic peroxisomes were identified only recently, and their putatively most conserved function seems to be the metabolism of inositol. The group Archamoebae includes anaerobes bearing both anaerobic peroxisomes and MROs, specifically hydrogenosomes in free-living Mastigamoeba balamuthi and mitosomes in the human pathogen Entamoeba histolytica, while the organelles within the third lineage represented by Pelomyxa remain uncharacterized. Results We generated high-quality genome and transcriptome drafts from Pelomyxa schiedti using single-cell omics. These data provided clear evidence for anaerobic derivates of mitochondria and peroxisomes in this species, and corresponding vesicles were tentatively identified in electron micrographs. In silico reconstructed MRO metabolism harbors respiratory complex II, electron-transferring flavoprotein, a partial TCA cycle running presumably in the reductive direction, pyruvate:ferredoxin oxidoreductase, [FeFe]-hydrogenases, a glycine cleavage system, a sulfate activation pathway, and an expanded set of NIF enzymes for iron-sulfur cluster assembly. When expressed in the heterologous system of yeast, some of these candidates localized into mitochondria, supporting their involvement in the MRO metabolism. The putative functions of P. schiedti peroxisomes could be pyridoxal 5′-phosphate biosynthesis, amino acid and carbohydrate metabolism, and hydrolase activities. Unexpectedly, out of 67 predicted peroxisomal enzymes, only four were also reported in M. balamuthi, namely peroxisomal processing peptidase, nudix hydrolase, inositol 2-dehydrogenase, and d-lactate dehydrogenase. Localizations in yeast corroborated peroxisomal functions of the latter two. Conclusions This study revealed the presence and partially annotated the function of anaerobic derivates of mitochondria and peroxisomes in P. schiedti using single-cell genomics, localizations in yeast heterologous systems, and transmission electron microscopy. The MRO metabolism resembles that of M. balamuthi and most likely reflects the state in the common ancestor of Archamoebae. The peroxisomal metabolism is strikingly richer in P. schiedti. The presence of myo-inositol 2-dehydrogenase in the predicted peroxisomal proteome corroborates the situation in other Archamoebae, but future experimental evidence is needed to verify additional functions of this organelle.

The Role of microorganisms in the petroleum industry is wide-ranging. To understand the role of microorganisms in hydrocarbon transformation, identification of such microorganisms is vital, especially the ones capable of in situ degradation. Microorganisms play a pivotal role in the degradation of hydrocarbons and remediation of heavy metals. Anaerobic microorganisms such as Sulphate Reducing Bacteria (SRB), responsible for the production of hydrogen sulphide (H2S) within the reservoir, reduces the oil quality by causing reservoir souring and reduction in oil viscosity. This paper reviews the diversity of SRB, methanogens, Nitrogen Reducing Bacteria (NRB), and fermentative bacteria present in oil reservoirs. It also reviews the extensive diversity of these microorganisms, their applications in petroleum industries, characteristics and adaptability to survive in different conditions, the potential to alter the petroleum hydrocarbons properties, the propensity to petroleum hydrocarbon degradation, and remediation of metals.

Many vertebrate animals employ anaerobic pathways during high-speed exercise, even if it imposes an energetic cost during postexercise recovery, expressed as excess postexercise oxygen consumption (EPOC). In ectotherms such a fish, the initial anaerobic contribution to exercise is often substantial. Even so, fish may recover from anaerobic pathways as swimming exercise ensues and aerobic metabolism stabilizes, thus total energetic costs of exercise could depend on swimming duration and subsequent physiological recovery. To test this hypothesis, we examined EPOC in striped surfperch (Embiotoca lateralis) that swam at high speeds (3.25 L s-1 ) during randomly ordered 2-, 5-, 10-, and 20-min exercise periods. We found that EPOC was highest after the 2-min period (20.9 mg O2 kg-1 ) and lowest after the 20-min period (13.6 mg O2 kg-1 ), indicating that recovery from anaerobic pathways improved with exercise duration. Remarkably, EPOC for the 2-min period accounted for 72% of the total O2 consumption, whereas EPOC for the 20-min period only accounted for 14%. Thus, the data revealed a striking decline in the total cost of transport from 0.772 to 0.226 mg O2 ·kg-1 ·m-1 during 2- and 20-min periods, respectively. Our study is the first to combine anaerobic and aerobic swimming costs to demonstrate an effect of swimming duration on EPOC in fish. Clarifying the dynamic nature of exercise-related costs is relevant to extrapolating laboratory findings to animals in the wild.

The present study aims to investigate effects of caffeine ingestion and sex difference on muscle performance, delayed-onset muscle soreness (DOMS), and various biomarkers under exercise-induced muscle damage (EIMD). Twenty (10 male and 10 female) healthy elite college athletes were recruited. Participants ingested either caffeine (6 mg/kg) or a placebo in a randomized, double-blind, and counterbalanced fashion at 24 and 48 h following EIMD. Muscle performance, DOMS, and blood samples were taken an hour before and an hour after supplementation. Caffeine ingestion restored impaired maximal voluntary isometric contractions (MVIC: 10.2%; MVICpost: 7.2%, both P < 0.05) during EIMD across both sexes. Following caffeine ingestion during MVIC, while affected by EIMD, an interaction was found in DOMS and serum K+ (both P < 0.05), with males showing greater attenuation (21.5 and 16.9%, respectively) compared with females (4.6 and 1.3%, respectively). DOMS demonstrated an inverse correlation with MVIC after caffeine ingestion both overall and among male athletes ( r = −0.34 and −0.54, respectively; P < 0.05) but not among female athletes ( r = −0.11; P > 0.05) under EIMD. In addition, caffeine ingestion increased postexercise serum glucose and lactate concentrations across both sexes (both P < 0.05). This is the first study to show that male athletes, compared with female athletes, experience a greater reduction in DOMS during enhanced MVIC when caffeine was consumed, suggesting men might receive greater ergogenic effects from caffeine when affected by EIMD. Furthermore, caffeine ingestion was able to restore impaired muscle power among elite collegiate athletes across both sexes. NEW & NOTEWORTHY Exercise-induced muscle damage (EIMD) reduces anaerobic/aerobic performance and increases delayed-onset muscle soreness (DOMS) during exercise. We show that acute caffeine supplementation at a dosage of 6 mg/kg seems to facilitate recovery of anaerobic muscle power and attenuate DOMS after EIMD across both sexes. Furthermore, male athletes, compared with female athletes, when caffeine was prescribed, experience a greater reduction in DOMS with better restoration of impaired maximal voluntary isometric contractions. This suggests that male athletes might benefit from the ergogenic effect of acute caffeine supplementation after the onset of EIMD.

A prospective, randomized, controlled study was designed to determine relative aerobic and anaerobic (lactic and alactic) contributions at supramaximal exercise intensities using two different methods. Thoroughbred racehorses ( n = 5) performed a maximal rate of oxygen consumption (V̇o2max) test and three supramaximal treadmill runs (105, 115, and 125% V̇o2max). Blood lactate concentration (BL) was measured at rest, every 15 s during runs, and 2, 5, 10, 20, 30, 40, 50, and 60 min postexercise. In method 1, oxygen demand was calculated for each supramaximal intensity based on the V̇o2maxtest, and relative aerobic and anaerobic contributions were calculated from measured V̇o2and the accumulated oxygen deficit. In method 2, aerobic contribution was calculated using the trapezoidal method to determine V̇o2during exercise. A monoexponential model was fitted to the postexercise V̇o2curve. Alactic contribution was calculated using the coefficients of this model. Lactate anaerobic contribution was calculated by multiplying the peak to resting change in BL by 3. Linear mixed-effects models were used to examine the effects of exercise intensity and method (as fixed effects) on measured outcomes ( P ≤ 0.05). Relative aerobic and anaerobic contributions were not different between methods ( P = 0.20). Horses’ mean contributions were 81.4, 77.6, and 72.5% (aerobic), and 18.5, 22.3, and 27.4% (anaerobic) at 105, 115, and 125% V̇o2max, respectively. Individual alactic anaerobic energy was not different between supramaximal exercise intensities ( P = 0.43) and was negligible, contributing a mean of 0.11% of the total energy. Relative energy contributions can be calculated using measured V̇o2and BL in situations where the exercise intensity is unknown. Understanding relative metabolic demands could help develop tailored training programs.NEW & NOTEWORTHY Relative energy contributions of horses can be calculated using measured V̇o2and BL in situations where the exercise intensity is unknown. Horses’ mean contributions were 81.4, 77.6, and 72.5% (aerobic), and 18.5, 22.3, and 27.4% (anaerobic) at 105, 115, and 125% of V̇o2max, respectively. Individual alactic capacity was unaltered between supramaximal exercise intensities and accounted for a mean contribution of 0.11% of energy use.

International audience; Mimachlamys varia is a sub-littoral bivalve encountered from Norway to the Mediterranean Sea, which lives mostly byssally attached to rocks. During the low tide period, M. varia individuals, located highest on the shore, may experience short time of aerial exposure and face a low availability of oxygen. Here we report a comparative metabolomic profiling of gill samples of M. varia obtained by both LC-QToF and APGC-QToF mass spectrometry, to analyze metabolic changes occurring during emersion in comparison with immersion. Scallops were grown in aquaria with a simulated intertidal environment mimicking short-duration air exposure that they might experience during extreme tides: alternating 2 h emersion and 10 h immersion. Our results show a switch from aerobic to anaerobic metabolism after only 2 h of emersion, with the resort to different pathways: glucose-lactate, glucose-succinate and aspartate-succinate pathways. Furthermore, carnitine-conjugated metabolites were found to accumulate during emersion, as well as urate. The level of tyrosine on the contrary was found to decrease. These findings indicate a complex metabolic reprogramming that occurs after a two hour emersion period and upon re-immersion. Furthermore, M. varia is used as sentinel species in pollution biomonitoring, through the assay of biomarkers to evaluate the effects of pollutants. Here we show that emersion induces a significant decrease of superoxide dismutase activity, an enzyme developed by bivalves to face oxidative stress and used as biomarker. These findings have to be taken into account to normalize sampling during campaigns of environmental monitoring, by taking in situ, as far as possible only immersed individuals.

Using RNA sequencing and qualitative and quantitative proteomics, we unravel alternative spliced isoforms and new ‘frame’ proteins during hypoxic germination in rice., Post-transcriptional mechanisms (PTMs), including alternative splicing (AS) and alternative translation initiation (ATI), may explain the diversity of proteins involved in plant development and stress responses. Transcriptional regulation is important during the hypoxic germination of rice seeds, but the potential roles of PTMs in this process have not been characterized. We used a combination of proteomics and RNA sequencing to discover how AS and ATI contribute to plant responses to hypoxia. In total, 10 253 intron-containing genes were identified. Of these, ~1741 differentially expressed AS (DAS) events from 811 genes were identified in hypoxia-treated seeds compared with controls. Over 95% of these were not present in the list of differentially expressed genes. In particular, regulatory pathways such as the spliceosome, ribosome, endoplasmic reticulum protein processing and export, proteasome, phagosome, oxidative phosphorylation, and mRNA surveillance showed substantial AS changes under hypoxia, suggesting that AS responses are largely independent of transcriptional regulation. Considerable AS changes were identified, including the preferential usage of some non-conventional splice sites and enrichment of splicing factors in the DAS data sets. Taken together, these results not only demonstrate that AS and ATI function during hypoxic germination but they have also allowed the identification of numerous novel proteins/peptides produced via ATI.

The ergogenic effects of carbohydrate (CHO) and caffeine (CAF) mouth rinse (MR) methods on anaerobic performance remains unclear. Therefore, the aim of this study was to investigate the effects of CHO, CAF, and CHO + CAF combination solutions in mouth on repeated vertical jumping (RVJ) performance in highly trained male athletes. Eight male athletes (mean age: 22 years) underwent test sessions four times with minimum 24-h intervals under fasting conditions. Participants rinsed their mouths with four different 25-ml solutions, namely, CHO (6.4% maltodextrin = 1.6 g), CAF (1.2% caffeine = 300 mg), placebo (PLA, saccharin), or CHO + CAF (6.4%+1.2%) combination, for 10 s and performed a 30-s RVJ test twice with a 5-min interval. Peak power output, vertical jump height, blood lactate level, fatigue index, and rate of perceived exertion of the RVJ tests for different intervention sessions were compared. The statistical significance level was set at p 0.05, g < 0.94). Our study did not elicit sufficient evidence to recommend highly trained male athletes the use of CHO- and CAF-MR separately or in combination to enhance jump performance. However, the fact that some differences have medium to large effect sizes suggests that the issue is still worth to be a potential topic for further research.

Anthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.

Rice production is shifting from transplanting seedlings to direct sowing of seeds. Following heavy rains, directly sown seeds may need to germinate under anaerobic environments, but most rice (Oryza sativa) genotypes cannot survive these conditions. To identify the genetic architecture of complex traits, we quantified percentage anaerobic germination (AG) in 2,700 (wet-season) and 1,500 (dry-season) sequenced rice genotypes and performed genome-wide association studies (GWAS) using 693,502 single nucleotide polymorphisms. This was followed by post-GWAS analysis with a generalized SNP-to-gene set analysis, meta-analysis, and network analysis. We determined that percentage AG is intermediate-to-high among indica subpopulations, and AG is a polygenic trait associated with transcription factors linked to ethylene responses or genes involved in metabolic processes that are known to be associated with AG. Our post-GWAS analysis identified several genes involved in a wide variety of metabolic processes. We subsequently performed functional analysis focused on the small RNA and methylation pathways. We selected CLASSY 1 (CLSY1), a gene involved in the RNA-directed DNA methylation (RdDm) pathway, for further analyses under AG and found several lines of evidence that CLSY1 influences AG. We propose that the RdDm pathway plays a role in rice responses to water status during germination and seedling establishment developmental stages.

Traditionally nitrogen transformation in constructed wetlands (CWs) has been attributed to the activities of aerobic autotrophic nitrifiers followed by anoxic heterotrophic denitrifiers. However, the nitrogen balances in such systems are far from being explained as a large fraction of the losses remain unaccounted for. The classical nitrification-denitrification theory has been successfully employed in certain unit processes by culturing fast-growing bacteria, but the CWs offer an ideal environment for slow-growing bacteria that may be beneficially exploited to achieve enhanced nitrogen removal by manipulating the environmental conditions in their favor. In the last three decades, many novel microorganisms have been isolated from CWs that have led to the discovery of some other routes that have made researchers believe could play a significant role in nitrogen transformation processes. The increased understanding of novel discerned pathways like anaerobic ammonium oxidation (ANAMMOX), heterotrophic nitrification and aerobic denitrification, which are mediated by specialized bacteria has indicated that these microorganisms could be enriched by applying selection pressures within CWs for achieving high rates of nitrogen removal. Understanding these novel nitrogen transformation processes along with the associated microbial population can provide new dimensions to the design of CWs for enhanced nitrogen removal.

Optical coherence tomography angiography (OCT-A) represents the most recent modality in retinal imaging for non-invasive and depth-selective visualization of blood flow in retinal vessels. With regard to quantitative OCTA measurements for early detection of subclinical alterations, it is of great interest, which intra- and extra-ocular factors affect the results of OCTA measurements. Here, we performed OCTA imaging of the central retina in 65 eyes of 65 young healthy female and male participants and evaluated individual physical fitness levels by standard lactate diagnostic using an incremental maximal performance running test. The main finding was that OCTA measurements of the foveal avascular zone (FAZ) area were associated with physical fitness. Using multivariate regression analysis, we found that running speed at the individual lactate threshold, a marker strongly associated with aerobic performance capacity, significantly contributed to differences in FAZ area (β = 0.111, p = 0.032). The data indicates that smaller FAZ areas are likely observed in individuals with higher aerobic exercise capacity. Our findings are also of interest with respect to the potential use of retinal OCTA imaging to detect exercise-induced microvascular adaptations in future studies.

Growth of Geobacter sulfurreducens PCA on lactate was enhanced by laboratory adaptive evolution. The enhanced growth was considered to be attributed to increased expression of the sucCD genes, encoding a succinyl-coenzyme A (CoA) synthetase. To further investigate the function of the succinyl-CoA synthetase, the sucCD genes were deleted from G. sulfurreducens. The mutant showed defective growth on lactate but not on acetate. Introduction of the sucCD genes into the mutant restored the full potential to grow on lactate. These results verify the importance of the succinyl-CoA synthetase in growth on lactate. Genome analysis of Geobacter species identified candidate genes, GSU1623, GSU1624, and GSU1620, for lactate dehydrogenase. Deletion mutants of the identified genes for d-lactate dehydrogenase (ΔGSU1623 ΔGSU1624 mutant) or l-lactate dehydrogenase (ΔGSU1620 mutant) could not grow on d-lactate or l-lactate but could grow on acetate and l- or d-lactate, respectively. Introduction of the respective genes into the mutants allowed growth on the corresponding lactate stereoisomer. These results suggest that the identified genes were essential for d- or l-lactate utilization. The lacZ reporter assay demonstrated that the putative promoter regions were more active during growth on lactate than during growth on acetate, indicating that the genes for the lactate dehydrogenases were expressed more during growth on lactate than during growth on acetate. The gene deletion phenotypes and the expression profiles indicate that there are metabolic switches between lactate and acetate. This study advances the understanding of anaerobic lactate utilization in G. sulfurreducens. IMPORTANCE Lactate is a microbial fermentation product as well as a source of carbon and electrons for microorganisms in the environment. Furthermore, lactate is a common amendment for stimulation of microbial growth in environmental biotechnology applications. However, anaerobic metabolism of lactate has been poorly studied for environmentally relevant microorganisms. Geobacter species are found in various environments and environmental biotechnology applications. By employing genomic and genetic approaches, succinyl-CoA synthetase and lactate dehydrogenase were identified as key enzymes in anaerobic metabolism of lactate in Geobacter sulfurreducens, a representative Geobacter species. Differential gene expression during growth on lactate and acetate was observed, demonstrating that G. sulfurreducens could metabolically switch to adapt to available substrates in the environment. The findings provide new insights into basic physiology in lactate metabolism as well as cellular responses to growth conditions in the environment and can be informative for the application of lactate in environmental biotechnology.