Assessment of benzene, toluene, ethyl-benzene, and xylene (BTEX) toxicity in soil using sulfur-oxidizing bacterial (SOB) bioassay

Chemosphere. 2019 Apr;220:651-657. doi: 10.1016/j.chemosphere.2018.12.102. Epub 2018 Dec 17.


The assessment of benzene, toluene, ethyl-benzene, and xylene (BTEX)-contaminated soil toxicity was performed using a sulfur-oxidizing bacteria (SOB) assay. The experiments were set up using an individual pollutant in a 25-mL bottle sealed with a rubber stopper and aluminum cap since BTEX are volatile. A large headspace volume (14 mL) was kept in the reactors to provide enough oxygen for the SOB. Soil samples were spiked with BTEX compounds in the concentration range of 1-1000 mg/kg. In reactors without BTEX compounds, approximately 85% of the theoretically required oxygen was consumed. Whereas, the reactors with benzene consumed in the range of 82-64% (5-100 mg/kg), those with toluene consumed 76-53% (1-50 mg/kg), those with ethyl-benzene consumed 44-71% (5-100 mg/kg), and those with xylene consumed 64-71% (1-10 mg/kg) of the theoretically required oxygen. The effective concentrations responsible for 50% growth inhibition (EC50) for benzene, toluene, ethyl-benzene, and xylene detection were 130.2, 1.2, 15.2, and 0.7 mg/kg, respectively. These results suggest that this SOB-based bioassay can detect BTEX pollutants in soils.

Keywords: BTEX toxicity; Benzene; Ethyl-benzene; Soil toxicity; Sulfur-oxidizing bacterial bioassay; Toluene; Xylene.

MeSH terms

  • Bacteria / metabolism
  • Benzene / analysis*
  • Benzene Derivatives / analysis*
  • Biodegradation, Environmental*
  • Biological Assay*
  • Oxidation-Reduction
  • Soil / chemistry*
  • Soil Pollutants / analysis
  • Sulfur
  • Toluene / analysis*
  • Xylenes / analysis*


  • Benzene Derivatives
  • Soil
  • Soil Pollutants
  • Xylenes
  • Toluene
  • Sulfur
  • Benzene
  • ethylbenzene