Effect of aromatic compounds on cellular fatty acid composition of Rhodococcus opacus

In cells of Rhodococcus opacus GM-14, GM-29, and 1CP, the contents of branc hed (10-methyl) fatty acids increased from 3% to 15 to 34% of the total fat ty acids when the cells were grown on benzene, phenol, 4-chlorophenol, chlo robenzene, or toluene as the sole source of carbon and energy, in compariso n with cells grown on fructose. In addition, the content of trans-hexadecen oic acid increased from 5% to 8 to 18% with phenol or chlorophenol as the c arbon source. The 10-methyl branched fatty acid content of R. opacus GM-14 cells increased in a dose-related manner following exposure to phenol or to luene when toluene was not utilized as the growth substrate. The results su ggest that 10-methyl branched fatty acids may participate in the adaptation of R. opacus to lipophilic aromatic compounds.