Exploring long chain n-alkane metabolism in Gordonia sp. strain SoCg

Many microorganisms are able to degrade aliphatic hydrocarbons and a relationship between n-alkane utilization and storage compound synthesis has been described in bacteria. The Gram positive GC-rich n-alkane degrader Gordonia sp. strain SoCg, isolated from a long-term accidentally contaminated beach in Sicily, is able to grow on long n-alkanes up to. It carries a single copy of the alkane hydroxylase gene alkB on its chromosome and its alk cluster revealed a genomic organization similar to other alk clusters of alkane-degrading Gram positive bacteria. The alk gene expression, analysed by Real-time RT-PCR, is induced by n-hexadecane and n-triacontane and coupled to alkane consumption. Interestingly, SPME GC-MS analysis revealed extracellular production of hexadecyl-hexadecanoic acid (wax ester), during growth on n-triacontane. Degenerated oligonucleotides were used to PCR amplify the Wax Esther Synthase/Acyl-CoA:Diacylglycerol Acyltransferase encoding gene (atfa), responsible for intracellular wax esther synthesis by estherification between palmitoyl-CoA and 1-haxadecanol in the n-alkane degrader Acinetobacter sp. ADP1. The amplicon showed 75% similarity sequence to a putative acyl-CoA transferase gene of Nocardia farcinica. Only one copy of atfa-like gene was detected in Gordonia SoCg chromosome. qRT-PCR analysis showed an up-regulation of atfa gene in the presence of long chain n-alkanes, correlating, for the first time, long chain n-alkane metabolism and wax esthers extracellular production.