Aerobic metabolism temperature

Optimum living conditions also give rise to intensification of aerobic metabolism. Within the zone of temperature tolerance, the intensification depends directly upon temperature (Van t Hoff-Arrhenius law). Many workers have shown that, in the optimum temperature zone, there are increases in oxygen consumption, activities of cytochrome oxidase and succinic dehyrogenase, respiration/phosphorylation ratio (respiratory control) and muscle electrical potential (Hochachka and Somero, 1973,1977 Wodtke, 1974 Khaskin, 1975 Derkatchev et al., 1976 Walesby and Johnston, 1980 Romanenko etal., 1991). 

Most clearly, the intensification of aerobic metabolism is manifested in the seasonal rhythms of vital activity this topic will be explored further in Chapter 4. Here we stress that the Black Sea fish that are of warm-water distribution spawn during the summer months when the temperatures are highest. Spawning consumes a great deal of energy and in the majority of these fish it lasts for 3 months. 

The biodegradation of crude oils in their reservoirs is well documented (M, 22). It occurs in the presence of meteoric water which supplies dissolved oxygen and nutrients including phosphate and fixed nitrogen. Microenvironments may exist in which aerobic and anaerobic activities occur in close proximity so that intermediates of aerobic metabolism may become substrates for anaerobic bacteria. In reservoirs, microbes are most active at the oil-water interface and at temperatures between about 20° and 60 to 75°C. 

Acetamiprid exhibits a very short half-life in soil. It is rapidly degraded by aerobic metabolism. Acetamiprid is stable to hydrolysis at environmental temperatures and it photodegrades slowly in water. It is... 

Reducing the 02 concentration around fresh fruits and vegetables reduces their respiration rate to an extent that varies with temperature, commodity, cultivar, and physiological age at harvest. Below a minimum of about 1 to 2% 02, a shift from aerobic to anaerobic respiration occurs with a concomitant increase in CO2 production Q0). The reduction in aerobic metabolism associated with reduced 02 levels is apparently not mediated by cytochrome oxidase, which has a K , value of 10"8 to 10 7 M 02 (11.12). It is more likely that reduction of aerobic respiration results from diminished activity of other oxidases such as ascorbic acid oxidase, polyphenol oxidase (FFO), and glycolic acid oxidase, whose affinities for 02 are 5 to 6 times lower than that of cytochrome oxidase (12). 

The final stage of biodegradation (Fig. 17.3) is determined by the mineralization level. Because organic carbon is converted to carbon dioxide in aerobic metabolism, the most widely used method of monitoring this stage is measuring the amount of carbon dioxide formed in a closed system. To ensure proper results, adequate conditions must be maintained in the closed system (humidity, temperature, pH, absence of toxic substances) for the existence of the microorganism culture. 

Moreover, temperature dependence of energy metabolism could be investigated with the setup described in section 3.4. It rendered the known parabolic behaviour of heat production rate as function of temperature with a maximum around 32 °C. Due to aerobic metabolism in the closed vessel the oxygen concentration dropped permanently. Lizards were able to cope with these changing conditions when longer lasting periods below 9.3 kPa p02 were avoided [83]. 

Fig. 22.7. Thermodynamic driving forces for various anaerobic (top) and aerobic (bottom) microbial metabolisms during mixing of a subsea hydrothermal fluid with seawater, as a function of temperature. Since the driving force is the negative free energy change of reaction, metabolisms with positive drives are favored thermodynamically those with negative drives cannot proceed. The drive for sulfide oxidation is the mirror image of that for hydrogentrophic sulfate reduction, since in the calculation 02(aq) and H2(aq) are in equilibrium.

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