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The influence of four low-frequency magnetic field (MF) ranges 10–300 Hz, 10–100 Hz, 10–50 Hz and 50–100 Hz in scanning regime (all frequencies from selected range were scanned during 100 s repetitively during 24 h) on baker's yeast cells Saccharomyces cerevisiae was examined by continuous measurements of cumulative O2 consumption and cumulative CO2 production over 24 h with Micro-Oxymax® respirometer. Besides respiration activity, measurements of cell growth and glucose uptake were performed as well. Statistical analysis indicated that, among all investigated low-frequency MF ranges, range from 10 Hz to 50 Hz had the greatest influence to yeast cell respiration and cell growth. More precisely, for this region, paired two sample one-tail t-test showed statistically significant differences in cumulative O2 consumption, cumulative CO2 production and S. cerevisiae cell number. Moreover samples exposed to MF range from 10 Hz to 50 Hz showed the same behavior in all five replicates: lower cumulative O2 consumption, higher cumulative CO2 production and higher cell number compared to control sample. This could be important from the application aspect, in industry (food, feed, brewery etc.) and biotechnology, because changes in cells metabolism are not caused by chemical treatment. This is the peer-reviewed version of the article: Bubanja IN, Loncarevic B, Ljesevic M, Beskoski V, Gojgic-Cvijovic G, Velikic Z, Stanisavljev D, The influence of low- frequency magnetic field regions on the Saccharomyces cerevisiae respiration and growth, Chemical Engineering and Processing - Process Intensification (2019), [https://doi.org/10.1016/j.cep.2019.107593] Published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3059]

Solid-state fermentation (SSF) is characterized by its complexity and heterogeneity. Use of agro-industrial residues as substrate avoids accurate measurement of biomass and substrates during the SSF process. Exhaust gas analysis has been used to indirectly estimate the biomass growth; however, these devices don't allow simultaneous measurements from different experimental units or bioreactors and they don't allow accurate simultaneous measurement of CO2, O2, and air-flow rate. A respirometry system based on CO2, O2, and air-flow measurement detectors fed by a system of 15 solenoid valves controlled by a programmable logic controller and a data logger was developed and evaluated during the growth of Rhizomucor pusillus in SSF. The respirometry system was compared to a classical chromatographic respirometer. Accurate measurements of CO2, O2, and air-flow rate allow precise and instantaneous estimation of some kinetic parameters associated with the respiration of the culture such as the specific CO2 production rate and the respiratory quotient. The respirometry system herein described allows online measurements of the microbial process allowing control procedures to be set in SSF processes.

This article presents a comprehensive overview on the functional role of respiration in horticultural crops pre- and postharvest. The various factors affecting respiration of horticultural commodities postharvest and the role of respiratory quotient in designing efficient packaging and storage systems.

Metabolic rate and gill ventilation in fish are useful indicators of physiological state, and provide important information for bioenergetic models. Oxygen-consumption rate provides a reliable indirect measurement of metabolic rate and can be measured using a variety of closed and open respirometers in fish at rest (routine, resting-routine, and standard metabolic rates) and using a swim tunnel respirometer where fish can be forced to maintain different levels of exercise intensity (swimming and active metabolic rates). Fish ventilation can be measured to provide ventilation frequency, stroke volume, and percentage utilization (% U ) of oxygen taken up at the gills, all of which are described in this article.

The strict standards of environmental control about to be enforced within the European Community have highlighted a need for more sophisticated monitoring and control of many parameters. Four recent innovations are described that may be used on sewage treatment plants. They are: 1) An on-line titrator used in the control of phosphate precipitation. 2) A respirometer to monitor the rate of oxygen uptake in a biomass. 3) A rapid chemical oxygen demand monitor. 4) A multifunctional unit, microprocessor controlled for various applications.

The oxygen consumption rates of 4th instar larvae of Chironomus plumosus , Chironomus anthracinus , Procladius crassinervis , and Glyptotendipes sp. from Lough Neagh have been measured. Measurements have been made at a range of naturally occurring temperatures on acclimated larvae in a constant pressure respirometer. Body weight and temperature have a clear effect on respiration. The data are analysed, the suitability of several models, and the likely contribution of chironomid respiration to oxygen depletion in Lough Neagh is briefly discussed.

Techniques for measuring the rates of feeding and of oxygen consumption by bivalve molluscs have been tested and applied under various conditions in the field, including working from a research vessel and from a small mobile laboratory on the shore. The animals are held in flowing water pumped from their natural environment, and conditions of temperature, salinity and ration are kept at ambient values. Rates of feeding are determined either by particle counts (by Coulter Counter) on water samples taken before and after the water has passed over the animal, or by passing the water through a fluorimeter for the continuous estimation of living particulate plant material. Rates of oxygen consumption are determined by recording the decline in oxygen tension in respirometer vessels which are isolated for brief periods of time from the flowing seawater. These techniques are described in more detail, and their uses in the field illustrated with data on two aspects of the environmental physiology of bivalves. 1: Rates of oxygen consumption by the mussel, Mytilus edulis over two annual cycles, to illustrate seasonal changes in metabolic rate under ambient conditions. 2: Feeding rates by Mytilus and by the cockle, Cardium edule, at various concentrations of suspended particulate matter, including a discussion of particle-size selection.

The oxygen consumption, movement activity and heart activity of non dormant and dormant larvae of Chironomus plumosus were investigated by means of a continuous flow polarographic respirometer. The oxygen consumption was correlated with the movement activity. On the other hand, a correlation of the oxygen consumption with the heart activity was not clearly detectable. The investigated activities of the non dormant and dormant larvae did not differ fundamentally.

Publisher Summary This chapter present a study on the aerobic metabolism of Artemia spec . In the study, the aerobic metabolism of the brine shrimp Artemia spec was measured with the Warburg constant volume respirometer technique. The experiments, as a part of the study, were carried out in air saturated artificial seawater and the respiratory rate was expressed as QO 2 . The most striking phenomenon in the biology of Artemia is the diapause of the dry cysts in the gastrula stage. This is characterized by the absence of any activity and no respiration can be detected. After hydration of the cysts, the development starts again and respiration increases fast. QO 2 is about 4μ1/h mg W D at the breaking stage and still rises after hatching up to a maximum of about 20 μl/h mg W D during the molting phase between instar II and instar III. After this molting, the QO 2 decreases slowly until the characteristic adult QO 2 is reached. The respiratory rate during ontogeny of Artemia shows several peaks that could all be correlated with molting stages. The chapter also presents a study on the respiratory pigment in Artemia .

Limpets can respire in air and water, but laboratory determined rates of oxygen consumption are influenced by the disturbing effects of removing the animals from their normal habitat. A respirometer is described that can be used to measure the oxygen consumption of undisturbed limpets on the shore. Field results are compared with those from the laboratory and an analysis made of the changes occurring in Patella during tidal cycles.

The influences of primary aliphatic alcohols on oxygen consumption of activated sludges in endogenous states were measured using a laboratory respirometer. The alcohols studied were n-propanol to n-octanol. Using beef extract as a reference substrate, results demonstrated a two-stage action for all alcohols. It was found that the alcohols enhanced the assimilation capacity of the biomass when they were below critical concentrations, but had inhibiting effects above these concentrations. Hypotheses and possible mechanisms of action were proposed to explain these results. An analogy with detergents was made.

Publisher Summary This chapter discusses the effect of Zn on the oxygen uptake in the gills of the dogfish Scyliorhinus Canicula. The effect of in vivo sublethal concentrations of Zn on the tissue respiration of the dogfish gills was investigated. The oxygen uptake was measured by means of a Warburg differential respirometer. Gill filaments were dissected and placed in the Warburg flasks in saline medium. Temperature was 20°C, and the fluid volume 3 ml. The oxygen uptake of isolated tissues was measured comparing control flasks with flasks containing the following concentrations: 180, 120, 60, 30, 15, 5, 1, and 0.2 ppm. The chapter also discusses the effect of adding Zn solutions, namely, 1, 5, 15, and 30 ppm, on the respiration of isolated gill tissue at 5 h. Higher concentrations, such as 60, 120, and 180 ppm, do not increase substantially the rate of inhibition, and the pattern of the curve reaches a plateau at about 60 ppm, and lower concentrations, such as 1 and 0.2 ppm, do not produce an increased respiration.

Publisher Summary This chapter presents a study on the gas exchange and acid–base balance in swimming coho-salmon. In the study, mass transport of O2, CO2, HCO3−, and H+ were measured of 600 g coho-salmons swimming in seawater for 6 h at four conditions: (A) 80% of the maximal sustained swimming speed (U-crit) at pH 7.95, (B) 80% U-crit, HCO3− < 0.3 mM, pH 7.95, (C) 50% U-crit, pH 7.10, and (D) 50% U-crit after 10–20 min at 120% U-crit, pH 7.95. The experiments were carried out in a tunnel respirometer. Oxygen levels were kept between 100 and 80% air saturation and pH was kept stable within 0.02 pH units. The RQ values for conditions A, B, and D were the same (0.6). In contrast, very low levels were found at low pH conditions indicating retainment of metabolic CO2. In all conditions, it was found that H+ and HCO3− production was imbalanced. Conditions A and D revealed excess H+ production, while B and C showed an excess of HCO3− production.

A way to control the degree of flocculence during continuous cultivation of Zoogloea ramigera in a chemostat was obtained by varying the level of Mg++ in the substrate medium. Samples taken out in steady-state were analyzed for diffusional effects by a pulse method, in which the respiration rates of the total culture and of the free organisms, the latter isolated by centrifugation, were measured at different levels of glucose in a respirometer. By use of a mathematical model a correlation between the degree of flocculation and the length of diffusion was found.

Publisher Summary This chapter discusses the coupling of phosphorylation with oxidation. The direct measurement of oxidative phosphorylation by determining the disappearance of inorganic phosphate or the formation of an organic phosphate compound is a very useful and widely applied procedure. However, if significant amounts of the organic phosphate formed are split by phosphatases or further metabolized with the release of inorganic phosphate, indirect assays must be used. In the course of assay, the enzyme system and substrate are incubated in a medium containing inorganic orthophosphate and a phosphate acceptor system. Oxygen consumption and the removal of inorganic phosphate are measured. The equipment used is a Warburg apparatus or other suitable respirometer for measuring oxygen uptake. The chapter also discusses the application of assay to crude enzyme preparations where qualitative detection of oxidative phosphorylation is easily made by noting the removal of some inorganic phosphate or the incorporation of P 32 into ATP, but quantitative assay requires careful consideration of possible side reactions and losses which may occur. Qualitative detection of phosphorylation can be made without measuring oxygen consumption. Quantitatively the disappearance of substrate or formation of product may be substituted for and at times preferred to the measurement of oxygen consumption.