Biodegradation of benzene and toluene using indigenous bacteria extracted from the soil of northwest Iran

Considering the role of hydrocarbon pollution in cancer, this research aims to investigate the degradation rate of benzene and toluene using bacteria extracted from soil, as well as to examine the compounds resulting from this decomposition.

Thirty soil samples, including agricultural soil and soil contaminated with hydrocarbons, were collected from the northwestern provinces of Iran. Bacteria were cultured in agar medium and subsequently extracted. To assess the decomposition of benzene and toluene, bacteria were separately cultured in a mineral culture medium containing a specific amount of benzene or toluene, and the percentage of decomposition was determined. Additionally, GC-Mass analysis was conducted to identify the compounds resulting from the decomposition of benzene and toluene. The type of bacteria responsible for the degradation was determined using biochemical methods and PCR

All the extracted bacteria exhibited the ability to decompose benzene and toluene, with the highest decomposition rates observed in bacteria extracted from refinery soil, averaging 55.85% for benzene and 49.39% for toluene. Agricultural and refinery soil bacteria displayed a higher decomposition rate for benzene compared to toluene. The majority of the compounds obtained from the decomposition had lower toxicity than benzene and toluene. Furthermore, the presence of the Streptomyces strain was confirmed in environments with the highest decomposition rates for benzene and toluene.

Streptomyces strains indigenous to soils contaminated with hydrocarbons demonstrated a high efficiency in converting benzene and toluene into organic compounds, reducing the associated risks.