GROWTH ON OCTANE ALTERS THE MEMBRANE LIPID FATTY-ACIDS OF PSEUDOMONAS-OLEOVORANS DUE TO THE INDUCTION OF ALKB AND SYNTHESIS OF OCTANOL

Growth of Pseudomonas oleovorans GPo1, which contains the OCT plasmid, on octane results in changes in the membrane phospholipid fatty acid composition, These changes were not found for GPo12, an OCT-plasmid-cu red variant of GPo1, during growth in the presence or absence of octan e, implying the involvement of OCT-plasmid-encoded functions. When rec ombinant strain GPo12(pGEc47) carrying the alk genes from the OCT plas mid was grown on octane, the cells showed the same changes in fatty ac id composition as those found for GPo1, indicating that such changes r esult from induction and expression of the alk genes, This finding was corroborated by inducing GPo12(pGEc47) with dicyclopropylketone (DCPK ), a gratuitous inducer of the alk genes. Further experiments shelved that the increase of the mean acyl chain length of fatty acids is rela ted to the expression of alkB, which encodes a major integral membrane protein, while the formation of trans unsaturated fatty acids mainly results from the effects of 1-octanol, an octane oxidation product.