Stress-induced changes of phospholipids in betaproteobacterium Aromatoleum aromaticum strain EbN1 due to alkylbenzene growth substrates.

The denitrifying betaproteobacterium strain EbN1 degrades toluene and ethylbenzene under anoxic conditions. Alkylbenzenes are unusual substrates, since their extraordinary chemical stability necessitates complex reactions and their toxic properties as solvents challenge cellular viability. To study the solvent impact on membrane lipid composition, strain EbN1 was grown at low, standard and semi-inhibitory concentrations of toluene (70, 240, and 740 microM) and ethylbenzene (80, 210, and 315 microM). At semi-inhibitory concentrations, phosphatidylglycerol increased at the expense of phosphatidylethanolamine. Moreover, phosphatidylcholine proportions increased and tentatively identified N-hexanoyl-phosphatidylethanolamine was detected. All observed changes in membrane lipid composition are interpreted as the organism's response to prevent the maceration of the cell membrane.