Characterization of indigenous Rhodococcus sp 602, a strain able to accumulate triacylglycerides from naphthyl compounds under nitrogen-starved conditions

Abstract : An indigenous bacterium (strain 602) isolated in this study from a polluted soil sample collected in Patagonia (Argentina) was investigated in relation to us metabolic responses under unbalanced growth conditions This strain was identified as Rhodococcus sp by molecular analyses Strain 602 showed the ability to degrade a wide range of compounds and to synthesize triacylglycerols under nitrogen-limiting conditions Cells were also able to accumulate triacylglycerols during cultivation on naphthalene and naphthyl-1-dodecanoate Triacylglycerols produced by resting cells in the presence of naphthyl-l-dodecanoate contained only short-chain length fatty acids (from C8 to Cr), suggesting an initial attack of the substrate by an esterase releasing I-naphthol and dodecanoic acid, which was subsequently degraded by a-oxidation On the other hand, naphthalene seemed to be degraded by a mono-oxygenase yielding 1-naphthol, which was then transformed to 4-hydroxy-1-tetralone and to other possible metabolic Intermediates On the basis of the results obtained, a pathway involved in the metabolism of both aromatic compounds under nitrogen starvation by strain 602 is proposed The results also demonstrated that Rhodococcus sp 602 maintains its metabolic activity even in the absence of a nitrogen source Intracellular triacylglycerols may help cells to maintain their catabolic activities under these growthrestricting conditions