Bacterial community structure evolution under prolonged BTEX and styrene exposure : a metagenomic study

Benzene, toluene, ethylbenzene, xylenes and styrene (BTEXS) are toxic pollutants that co-occur in wastewater effluents from petrochemical and chemical industries. Seeking effective and efficient treatments for these effluents is crucial in eliminating serious health and environmental issues that would otherwise arise from the anthropogenic release of BTEXS. This work examined the evolution in bacterial profiles under prolonged BTEXS enrichment and identified biomarkers associated with the enriched microbial community. The volatile suspended solids (VSS) increased by 24% within 15 months, indicating that the microbial community had evolved to assimilate BTEXS as an energy and carbon source. Six key biomarkers and three indicative biomarkers were identified at the bacterial order level. Rhizobales, Burkholderiales and Actinomycetales were identified as key biomarkers of the core BTEXS-degrading population while Sphingobacteriales, Flavobacteriales and Bacteroidales were identified as key biomarkers of the secondary BTEXS-degrading population. Xanthomonadales, Pseudomonadales and Clostridales may serve as indicative biomarkers of the operating conditions (i.e. BTEXS loading and oxygen levels). This new knowledge is beneficial to engineers in selecting seed inoculum and monitoring reactor stability. Furthermore, it potentially enables engineers to leverage on innate microbial characteristics to develop biological treatments for an effective and efficient remediation of BTEXS-laden wastewater effluents.