Role of plasmid in the degradation of petroleum hydrocarbon by Pseudomonas fluorescens NS1.

In this study the role of plasmid in Pseudomonas fluorescens, isolated from petroleum contaminated soil on hexadecane degradation was assessed. The organism was able to utilize hexadecane as sole carbon source and also reduce surface tension up to 27 mN/m. The organism harboured a plasmid of approximately 1.8 kb. Plasmid curing and transformation of plasmid DNA into E. coli revealed that the plasmid was involved in hexadecane degradation. When compared to P. fluorescens, no significant growth was observed with wild-type E. coli strain. P. fluorescens degraded 95% of hexadecane (0.4% (v/v)) whereas the transformed strain degraded 92% of hexadecane in 120 h, which was almost equivalent to the degradation by P. fluorescens. The wild-type E. coli showed no significant degradation of hexadecane whereas, the plasmid transformed E. coli was able to degrade hexadecane, which indicates the expression of the catabolic genes in the transformed E. coli strain.