We report changes of the content of anionic phospholipids in Bacillus subtilis in response to hypoxic conditions and inhibition of terminal respiration. Cardiolipin accumulates rapidly when bacteria are suspended in non-growth medium under reduced aeration or exposed to the inhibitor cyanide; the increase of cardiolipin occurs at the expense of its precursor phosphatidylglycerol and is temperature-dependent. Depending on the extent of hypoxic stress, membranes containing different levels of cardiolipin can be isolated from B. subtilis cells. The NADH oxidase activity in cardiolipin-enriched membranes is cyanide-resistant; furthermore O2 consumption measurements indicated that cardiolipin-enriched cells are resistant to cyanide. Results point out a possible interdependence between the effect of cyanide on cardiolipin metabolism and the effect of cardiolipin on the effectiveness of cyanide inhibition.
Keywords: CL, cardiolipin; Cardiolipin; Cyanide; Hypoxia; L-PG, lysyl-phosphatidylglycerol; NAO, 10-N-nonyl-acridine orange; NGM, non-growth medium; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PGL, phosphoglycolipid.; Phosphatidylglycerol.