Energetics of Growth in a Tyrothricin-producing Strain of Bacillus brevis

Abstract

S U M M A R YThe particulate NADH oxidase activity of Bacillus brevis is inhibited by tyrocidine and the kinetics of inhibition indicate that the NADH dehydrogenase region is the primary site of action. A decrease in NADH oxidase activity of electron transport particles and of NADH oxidase activity of whole organisms occurs in batch culture in the later stages of growth when production of tyrothricin increases. That respiration exhibited by growing cells takes place via the respiratory electrontransport system is indicated by the similarities in levels of activity and cyanide sensitivity of endogenous and NADH oxidation of growing cells. Exponential growth on glycerol asparagine media is diphasic, a slower growth rate commencing as the 0, tension of the culture approaches zero and tyrothricin production increases. Molar growth yield data based on overall measurements of growth related to 0, uptake in batch culture lead to low ATP/O ratios. In an attempt to determine Yo and ATP/O ratios under optimum conditions of growth a method is described which was based entirely on the growth and respiratory activity of exponentially growing cells. Such measurements led to higher values for Yo and to ATP/O ratios approaching 3, indicating the participation of three sites of phosphorylation during exponential growth. Tyrocidine and DNP inhibited growth, the tyrocidine at concentrations similar to those produced at the end of the exponential growth phase. Yo/Yl,, ratios (ATP/O ratios) on glycerol asparagine media were lower than on peptone yeast extract medium which yielded no tyrothricin, a possible indication that some form of uncoupling occurs in organisms grown on glycerol asparagine medium which does not yield tyrothricin.

The Multifaceted Antibacterial Mechanisms of the Pioneering Peptide Antibiotics Tyrocidine and Gramicidin S

“…Surprisingly, both AtpA and SdhA partially lost their membrane association after treatment with the tyrocidines ( Fig. 5D ), explaining inhibition of electron transport chain enzymes reported in an early study ( 29 , 59 ). In contrast, gramicidin S had no marked effect on the localization of these proteins, suggesting that its effect on cellular ATP levels is probably due to delocalization of cytochrome c ( 39 ) and partial membrane depolarization.…”

The Effect of Inhibitors on the Electron-transport Chain of Bacillus brevis. Evidence for Branching of the NADH Oxidase Respiratory Chain

“…The possibility cannot be disregarded, however, that reduced oxygen tension during late growth may have influenced the NADH oxidase (Seddon & Fynn, 1973). The results here indicate that NADH, succinate and cytochrome c oxidases all show different levels of inhibition with the cyclic decapeptide antibiotics.…”

“…Increased tyrothricin production at later stages of growth (Seddon & Fynn, 1973) may affect the primary NADH dehydrogenase site, but the tyrothricin cannot be present ? Relative to the NADH oxidase activity as 100 %.…”

“…NADH oxidase activity varies with culture age (Seddon & Fynn, 1973). In order to minimize the effects of endogenous tyrothricin production the electron-transport particles were prepared from organisms freshly harvested from the exponential phase of growth, before substantial amounts of tyrothricin were produced.…”

Adenine Nucleotide Pool and Energy Charge During Growth of a Tyrothricin-producing Strain of Bacillus brevis

“…Dinitrophenol and tyrothricin, which are uncouplers of oxidative phosphorylation, inhibited growth of the organism when added to the culture medium. Seddon & Fynn (1973) proposed that the endogenous tyrothricin normally produced during growth is inactivated by compartmentalization or by binding with phospholipid within the cell. An investigation was therefore undertaken of the adenine nucleotide pool and E.C.…”