Abstract

Acinetobacter strains LT₁ and V₂ were grown in Bushnell-Haas medium with 1% diesel and their expression levels of eight diesel-degrading genes were evaluated by quantitative polymerase chain reaction (PCR). LT₁ and V₂ isolates achieved 86.2 and 89.7% degradation respectively, after 60 days with no significant differences in expression, in comparison with 16S rRNA, rubB and lipB. LT₁ showed higher expression levels of rubA, alkM, alkR and xcpR genes during the initial stages of incubation corresponding to higher level of degradation rate. Amplification of alkM, alkR and xcpR genes of V₂ indicated more than one enzyme system involved in the process. Low lipB and lipA expression in LT₁ and no lipA expression in V₂ suggested the absence of lipases in degradation; however, estB gene was predominantly expressed in V₂. Thus, isolates LT₁ and V₂ possessed comparable efficiency in degrading diesel; however, more complex systems have been employed by V₂i n degradation process.

Key words: qPCR, diesel degradation, Acinetobacter calcoaceticus, bioemulsifier, gene expression.