Comparative study of energy-transducing properties of cytoplasmic membranes from mesophilic and thermophilic Bacillus species

Abstract

The properties of enzymes involved in energy transduction from a mesophilic (Bacillus subtilis) and a thermophilic (B. stearothermophilus) bacterium were compared. Membrane preparations of the two organisms contained dehydrogenases for NADH, succinate, L-ac-glycerophosphate, and L-lactate. Maximum NADH and cytochrome c oxidation rates were obtained at the respective growth temperatures of the two bacteria. The enzymes involved in the oxidation reactions in membranes of the thermophilic species were more thermostable than those of the mesophilic species. The apparent microviscosities of the two membrane preparations were studied at different temperatures. At the respective optimal growth temperatures, the apparent microviscosities of the membranes of the two organisms were remarkably similar. The transition from the gel to the liquid-crystalline state occurred at different temperatures in the two species. In the two species, the oxidation of physiological (NADH) and nonphysiological (N,N,N',N'-tetramethyl-p-phenylenediamine or phenazine methosulfate) electron donors led to generation of a proton motive force which varied strongly with temperature. At increasing temperatures, the efficiency of energy transduction declined because of increasing H+ permeability. At the growth temperature, the efficiency of energy transduction was lower in B. stearothermophilus than in the mesophilic species. Extremely high respiratory activities enabled B. stearothermophilus to maintain a high proton motive force at elevated temperatures. The pH dependence of proton motive force generation appeared to be similar in the two membrane preparations. The highest proton motive forces were generated at low external pH, mainly because of a high pH gradient. At increasing external pH, the proton motive force declined.

Bioenergetic studies of coal sulfur oxidation by extremely thermophilic bacteria. Final report, September 15, 1992--August 31, 1997

“…By compromising cellular bioenergetics in various ways, iron or sulfur oxidation may be enhanced as a means to compensate for a nonideal situation. In fact, energy coupling by thermoacidophiles at high temperature and low pH may be relatively inefficient even under normal growth conditions in view of the high maintenance coefficients and the high membrane permeability to protons found for these organisms when compared to mesoacidophiles (De Vrij et al, 1988;Farrand et al, 1983;Konings et al, 1992;Kuhn et al, 1980;McKay et al, 1982). On the other hand, Elferink et al (1994) showed SulfoZobus acidocaldarius has a relatively low proton permeability at 80°C compared to Escherichia coli or Bacillus stearothennophiZus.In any case, Extreme thermoacidophiles presumably need to invest additional metabolic energy for maintenance of a suitable intracellular pH under stress.…”

Application of thermostable reaction centers from Chloroflexus aurantiacus as a protonmotive force generating system

“…The medium was inoculated with 100 ml of an exponentially growing culture. Bacillus stearothermophilus ATCC 7954 was grown at 63°C with vigorous aeration in a medium containing 20 g/l tryptone, 10 g/l yeast extract and 172 mM NaCI (pH 7.0) as described [11]. C. fervidus ATCC 43204 was grown anaerobically at 68°C in the TYEG medium as described [13].…”

“…Due to subtle differences in hydrogen bonding, disulfide bridges and ionic or hydrophobic interactions proteins of thermophilic microorganisms are generally more thermostable and thermoactive then those of mesophilic micro-organisms [5][6][7][8]. The membranes of thermophilic bacteria are adapted to elevated temperatures by changes in fatty acid and polar headgroup composition of the lipid bilayer [3,[9][10][11]. Thermophilic Bacillaceae have been studied most extensively with respect to thermostability of membrane proteins and functional properties of the cytoplasmic membranes (for review see Ref.…”

Amino acid transport in the thermophilic anaerobe Clostridium fervidus is driven by an electrochemical sodium gradient

“…In general, thermophiles have altered their membrane compo-sition so that at the same temperature the membranes are more rigid and less fluid than the membranes of mesophiles (23). The membrane of the aerobic thermophile Bacillus stearothennophilus is, at its growth temperature (65°C), equally viscous as its mesophilic counterpart Bacillus subtilis at its growth temperature (37°C); however, the H+ permeability is much higher (5,8). B. stearothermophilus compensates the increased H+ permeability by investing more metabolic energy in very active H+ pumps present in its membrane (5,8).…”

“…The membrane of the aerobic thermophile Bacillus stearothennophilus is, at its growth temperature (65°C), equally viscous as its mesophilic counterpart Bacillus subtilis at its growth temperature (37°C); however, the H+ permeability is much higher (5,8). B. stearothermophilus compensates the increased H+ permeability by investing more metabolic energy in very active H+ pumps present in its membrane (5,8). Secondary transport systems in this * Corresponding author.…”