Relationship between cardiolipin metabolism and oxygen availability in Bacillus subtilis

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.

▸ Bacillus subtilis lipids were analyzed by TLC and MALDI-TOF/MS. ▸ Hypoxic stress stimulates the conversion of PG in CL. ▸ Membrane CL levels correlate with the extent of hypoxic stress. ▸ The respiratory poison cyanide induces CL membrane enrichment. ▸ CL-rich cells or membranes are resistant to cyanide.