Isolation and Characterization of Naphtalene Degrading Bacteria

Abstract

ABSTRACT Biodegradation of organic pollutants such as polycyclic aromatic hydrocarbons using soil microorganisms where they use these compounds as carbon and energy source, is the safe, cheap and environment friendly way. In the present study, bacterial isolates utilizing the naphthalene as sole carbon and energy were characterized taxonomically, through biochemical tests and for their degradation potential for naphthalene. Bacterial samples were isolated from crude oil contaminated soil. A total of 8 isolates were initially screened, six of these isolates were checked for growth on M9 medium containing up to 100µg/g of naphthalene. Two bacterial isolates S3 and F3 were selected on the basis of their best growth on naphthalene but S3 isolate showed the highest ability for degradation and thus was subjected to 16S rRNA sequence for identification. Phylogenetic analyses based on 16S ribosomal RNA sequences of S3 showed that it was closely related to Pseudomonas aeruginosa strain DSM 50071. The effects of temperature, pH and salt concentration on bacterial growth were also studied.

Biodegradation study of naphthalene was carried out by Pseudomonas sp.S3 and F3 at optimum pH and temperature. The optimum pH and temperature were 7 and 37ºC respectively, for bacterial growth. The biodegradation efficiency of Pseudomonas sp.S3 was 77.77% of naphthalene after 7 days of incubation, the detectable concentration of naphthalene (163.63µg) was decreased to 36.36µg. For F3 biodegradation efficiency was 61.11% of naphthalene after 7 days of incubation and the detectable concentration of naphthalene (163.63µg) was decreased to 63.63µg, as determined by LC/MS analysis.