Degradation of low molecular weight polycyclic aromatic hydrocarbons by microorganisms isolated from contaminated soil

Degradation of low molecular weight PAHs by two bacterial species Micrococcus luteus and Kocuria rosea has been reported for the first time in the present study. Three fungal species of Aspergillus were also studied for their PAH-degradation potential. The microorganisms were isolated from oil contaminated soil and adapted with an exposure to high dose of PAH compounds for one year under laboratory conditions. The efficiency towards biodegradation increased from Kocuria rosea (55.4%) to Aspergillus ficuum (57.2%) to Aspergillus flavus (63.2%) to Micrococcus luteus (63.6%) to Aspergillus fumigatus (63.9%). Maximum degradation was observed for naphthalene followed by phenanthrene, fluoranthene, and pyrene for bacteria. M. luteus could degrade the compounds at a faster rate than K. rosea. A. flavus and A. fumigatus strains were better adapted to degradation. On the other hand, the removal efficiency of A. ficuum was considerably less, but it could remove fluoranthene efficiently. Observed trend of PAH biodegradation may be a function of melting point, aqueous solubility, structure of the PAH compound, and microbial growth. The microorganisms reported in the study can prove useful in remediation of PAH contaminated sites and may find an application in the design of novel bioremediation protocols.