Isolation of toluene-degrading bacteria and investigation of the ability to decompose aromatic hydrocarbon mixture in laboratory wastewater

Toluene is an aromatic hydrocarbon commonly used as a solvent in industry and as one of the main components of gasoline. Due to its solubility in water, the compound may accumulate in surface water or reachgroundwater causing harmful effects on human health. Twenty bacterial strains grown on a minimal medium supplemented with toluene as the sole carbon source were isolated from the sediment samples of a laboratory wastewater treatment system. Among these, strains TL5 and TL27 performed toluene degradation capability. After 24 hours of incubation in a minimal medium supplemented with toluene (0.025% v/v) as the only carbon source, chromatographic data recorded that TL5 and TL27 degraded 96.71 and 100% toluene, respectively. In a minimal medium with a mixture of aromatic hydrocarbons added, after 4 days of incubation, toluene and benzaldehyde were completely degraded while phenol, xylene, acetophenone, and pyridine were degraded 88.27, 40.9, 34.67, and 23.26%, respectively. Based on 16S-rRNA sequence analysis, the potential aromatic hydrocarbon degrader was genetically identified as Enterobacter sp. TL27.