Aerobic Degradation of Naphthalene, Fluoranthene, Pyrene and Chrysene Using Indigenous Strains of Bacteria Isolated from a former Industrial Site

Abstract

Four bacterial strains were isolated from a former industrial site contaminated with organic and inorganic pollutants for decades. The isolation was done using naphthalene as sole source of carbon and energy during the enrichment. 16S rRNA gene sequence analyses of the four isolates (OC1, OC2, OC3, and OC4) assigned the strains to the genus, Enterobacter (OC1) and Pseudomonas (OC2, OC3, and OC4). The degradation and growth behavior of the four isolates was investigated on naphthalene, fluoranthene, pyrene and chrysene. All the strains utilized naphthalene, fluoranthene, chrysene but pyrene partially, as sole sources of carbon and energy. The time course studies using relative concentration > 100ppm, >115ppm, > 89ppm and > 12 ppm for naphthalene, fluoranthene, pyrene and chrysene respectively, resulted in rapid exponential increases in cell numbers and concomitant disappearance of the test substrates. Naphthalene was degraded between the range of 25 % and 99%, while chrysene degradation ranged between of 35 and 69%, pyrene 4 - 21% and fluoranthene 7 -19 %. Our results suggest that contaminated, former industrial sites contain a capable microbial community that may be used for bioremediation of the site.