Isolation of a BTEX-degrading bacterium, Janibacter sp. SB2, from a sea-tidal flat and optimization of biodegradation conditions.

An enrichment culture was established using seawater containing BTEX (benzene, toluene, ethylbenzene and xylene) compounds to isolate a BTEX-degrading bacterium from contaminated sea-tidal flat. The enriched microbial communities were characterized by 16S rRNA-based DGGE profiling, which indicated that a Janibacter species was dominant during the enrichment. Strain SB2, corresponding to the major band and able to degrade all BTEX compounds, was isolated and characterized. NH4Cl, NaH2PO4, cell mass and BTEX concentrations were used as independent variables to optimize the degradation of BTEX by strain SB2 in a tidal flat and a statistically significant (R(2)=0.8933, p<0.0001) quadratic polynomial mathematical model was suggested. For the initial concentration of 240 mg/L BTEX in a slurry system containing 3.0×10(7) cells/L, 45.5% BTEX removal was observed under the optimum condition of NH4Cl and NaH2PO4, while 32.2% BTEX removal was observed under the untreated condition of NH4Cl and NaH2PO4.