Studies on hydrocarbon degradation by the bacterial isolate Stenotrophomonas rhizophila (PM-1) from oil spilled regions of Western Ghats of Karnataka

Abstract

The hydrocarbon utilizing capability of Stenotrophomonas rhizophila (PM-1), isolated from oil contaminated soil composts from Western Ghats region of Karnataka was analyzed. In the bioremediation experiment, ONGC heavy crude oil and poly aromatic hydrocarbons (PAHs) utilization by the bacterial isolate was studied. Preliminary studies by DCPIP method suggests, the isolate PM-1 having the potential PAHs and crude oil utilization ability. The degradation of 2 % heavy crude oil and other PAHs from the isolate PM-1 was assessed by Total Plate Count (TPC), Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) level at regular time intervals. Increased in population densities with simultaneous increase in BOD and COD ratio correlates with the UV spectrophotometry result by change in the λ_max (from 249 nm to 278 nm), gas chromatographic analysis (25.00 %) and total petroleum hydrocarbon (TPH) (65.78 %). A substrate specificity test of the isolates on different hydrocarbons (PAHs) showed that the isolate PM-1 had good growth on decanol, hexadecane, toluene, dodecane, engine oil, benzene, phenol, ethyl benzene, pentadecane, tetradecane, octane, oleic acid and naphthalene. The breakdown of the molecular structure in heavy crude oil and in PAHs indicates, the loss of conjugation in parental hydrocarbons shows the degradation potency of the bacterial isolate (PM-1).

Keywords: Stenotrophomonas rhizophila, Bioremediation, PAHs, Crude oil, Western Ghats