Microbial degradation of n-hexadecane in mineral salt medium as mediated by degradative enzymes

Abstract

In the present study, n-hexadecane degradation in MSM was investigated by three bacteria identified as Pseudomonas aeruginosa PSA5, Rhodococcus sp. NJ2 and Ochrobactrum intermedium P2, isolated from petroleum sludge. During 10days of incubation, n-hexadecane was degraded to 99% by P. aeruginosa PSA5, 95% by Rhodococcus sp. NJ2 and 92% by O. intermedium P2. During degradation process, the induction of catabolic enzymes alkane hydroxylase, alcohol dehydrogenase and lipase were also examined. Among these enzymes, the highest activities of alkane hydroxylase (185μmolmg−1 protein) and alcohol dehydrogenase (75.78μmolmg−1 protein) were recorded in Rhodococcus sp. NJ2 while lipase activity was highly induced in P. aeruginosa PSA5 (48.71μmolmg−1 protein). Besides, accumulation of n-hexadecane in inclusion bodies was found to be maximum 60.8gl−1 in P. aeruginosa PSA5, followed by Rhodococcus sp. NJ2 (56.1gl−1) and the least (51.6gl−1) was found in O. intermedium P2. Biosurfactant production by bacterial strains was indicated by the reduction in surface tension and induction of cell surface hydrophobicity and pseudosolubilization which facilitated n-hexadecane degradation.