Bacteria to Degrade Toluene

Prelims level : Science & Technology - Biotechnology Mains level :
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  • Researchers from the University of Delhi and Indian Institute of Technology (BHU), Varanasi, have successfully degraded toluene into less-toxic by-products using bacteria isolated from soil and effluents near an oil refinery.


  • • The researchers also tested the bacterial strain for the degradation of benzene, phenol, and xylene and they showed effective results towards degradation of these compounds both individual compounds and their mixtures.
  • In laboratory conditions, the bacteria were able to degrade these petrochemical wastes in both soil and water samples. More studies are needed to design industrial-scale bioreactors for taking up large-scale degradation of petrochemical waste.
  • • The bacteria were isolated from the samples, identified and studied for their toluene-degrading abilities. To the soil and effluent samples containing some bacteria 100 mg/L of toluene was added and incubated for four weeks.
  • They isolated eight to 10 strains of bacteria and found that a particular bacteria Acinetobacter junii showed good degrading potential about 80% of toluene (50 ppm) in a liquid medium was degraded within 72 hours.
  • A consortium of A. junii bacteria was found to be more effective than using a single strain. Different bacterial strains have different characteristic potential to degrade intermediate by-products formed during the degradation process and, hence, increase the efficiency.
  • The bacteria use up this toluene as their carbon source in the presence of oxygen. Though most of the waste degradation studies have involved the use of bacteria that grow in an anaerobic environment, we tried an aerobic one and succeeded.


  • • Toluene also known as aromatic hydrocarbon. It is a colourless, water-insoluble liquid with the smell associated with paint thinners. Toluene is predominantly used as an industrial feedstock and a solvent.
  • Toluene is one of the petrochemical wastes that get released without treatment from industries such as refineries, paint, textile, paper and rubber. Toluene occurs naturally at low levels in crude oil and is a by-product in the production of gasoline by a catalytic reformer or ethylene cracker. It is also a by-product of the production of coke from coal.
  • Toluene has been reported to cause serious health problems to aquatic life, and studies point that it has genotoxic and carcinogenic effects on human beings. Sometimes used as a recreational inhalant and has the potential of causing severe neurological harm.
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