Energy conservation in Bacillus megaterium

Abstract

1. The respiratory chain energy conservation systems of Bacillus megaterium strains D440 and M have been investigated following growth in batch and continuous culture. Respiratory membranes from these strains contained cytochromes b, aa3, o and b, c, a, o, respecitvely; both readily oxidised NADH but neither showed any pyridine nucleotide transhydrogenase activity. 2. Whole cells of both strains exhibited endogenous leads to H+/O ratios of approximately 4; when loaded with specific substrates the resultant leads to H+/O ratios indicated that proton translocating loops 1 and 2 were present in strain D440 and that loops 2 and 3 were present in strain M. 3. In situ respiratory activities were measured as a function of dilution rate during growth in continuous culture. True molar growth yields with respect to oxygen (Y02) of approximately 50 g cells-mole oxygen-1 were obtained for most of the nutrient limitations employed. Average values for YATP of 12.7 and 10.8 g cells-mole ATP equivalent-1 were subsequently calculated for strains D440 and M respectively. 4. Energy requirements for maintenance purposes were low in energy-limited cultures but were substantially increased when growth was limited by nitrogen source (NH+/4). Under the latter conditions there is probably a partial uncoupling of energy-conserving and energy-utilising processes leading to energy wastage.

The effect of temperature on the molar growth yield and maintenance requirement of Escherichia coli W during aerobic growth in continuous culture

“…coli W was grown in carbon-limited continous culture using a 500 ml capacity chemostat fitted with a simple oxygen analyser [11][12][13]. The culture medium consisted of a minimal salts solution [14] supplemented with nitrilo-triacetic acid (0.1 g • litre -1) plus 7 mM glycerol.…”

“…The selected temperature (+ 0.1°C) was maintained by immersing the growth chamber in a controlled-temperature water tank. In situ respiratory activities of growing cells were determined from the difference in the oxygen concentration of the input and effluent air, the air flow rate and the steady-state culture density as described in previous communications from this laboratory [11][12][13]. True molar growth yields with respect to glycerol utilisation (Y~tX~rol) were determined by essentially standard procedures in which observed growth yields obtained at a series of dilution rates were extrapolated to an infinite dilution rate [10,15].…”

Growth Regulation in the Mycobacterial Cell

“…Based on these calculations, the theoretical ATP yield is 19 moles of ATP produced per mole of glycerol consumed. In E. coli and Bacillus megaterium the complete oxidation of one mole of glycerol yields 14 moles of ATP [56,57].…”

Physiology of Mycobacteria

“…Based on these calculations, the theoretical ATP yield would be 15 moles of ATP produced per mole of glycerol consumed. In E. coli and Bacillus megaterium , the complete oxidation of one mole of glycerol yields 14 moles ofATP (Downs and Jones, 1975; Farmer and Jones, 1976). …”