Sequencing and analysis of plasmids pAV1 and pAV2 of Acinetobacter venetianus VE-C3 involved in diesel fuel degradation

Acinetobacter venetianus strain VE-C3 was isolated in the Venice lagoon (Italy) as a strain able to degrade diesel fuel oil. This strain possesses genes of the alkane monoxygenase complex responsible for n-alkane degradation and carries two plasmids, pAV1 (10820 bp) and pAV2 (15135 bp), which were supposed from the analysis of Alk(-) mutant strains to harbour genetic determinants for hydrocarbon degradation. In this work we determined the nucleotide sequence of both plasmids and showed the presence of a putative aldehyde dehydrogenase gene, essential for hydrocarbon degradation, on plasmid pAV2, and of an ORF similar to alkL gene present on pAV1 plasmid. These data, combined with genetic reports indicating that strains lacking one of the two plasmids or carrying transposon insertion on pAV1, are defective in n-alkane degradation, suggest a complex genomic organisation of genes involved in alkane degradation in A. venetianus VE-C3. In this bacterium these genes are carried by both the chromosome and the plasmids, while in Acinetobacter sp. strain ADP1 and M1 all the genes for alkane monoxygenase complex are located only on the chromosome.