Community Diversity, Degrading Gene And Compatible Solutes Of BTEX Degrading Bacterial Consortium In High Salinity

Benzene, toluene, ethylbenzene and xylenes (BTEX) contaminants have been widely detected in high salinity environment. This study succeeded in acclimating and enrichment a microbial community to degrade BTEX in wide range of salinity. The enrichment degraded120mg/L toluene within5d in the presence of2M NaCl and150mg/L toluene within7days in the presence of1or1.5M NaCl, respectively. PCR-DGGE profiles demonstrated that the dominant species in the enrichments clustered in five phyla:Gammaproteobacteria, Sphingobacteriia, Prolixibacter, Flavobacteriia and Firmicutes. Marinobacter sp., Prolixibacter sp., Balneola sp., Zunongwangia sp., and Halobacillus sp. were the dominant species. PCR detection of the genotypes of the key enzyme involved in the bacterial BETX degradation revealed that the degradation pathways contained all the known initial oxidative attack of BTEX by monooxygenase and dioxygenase. And the subsequent ring fission was catalysed by catechol1,2-dioxygenase and catechol2,3-dioxygenase. Nuclear magnetic resonance (NMR) spectroscopy profiles showed that the toluene degrading bacterial consortium adjusted the osmotic pressure by ectoine and hydroxyectoine as compatible solutes to be suitable to the different salinity conditions. These results are significant for understanding natural attenuation potential of BTEX at salt environment via the identity of microbes and the key enzymes involved in the degradation steps.