Microbial Degradation of Toluene and Xylene by a Newly Isolated Native Bacterial Strain Bacillus subtilis RD20

IJEP 43(8): 675-685 : Vol. 43 Issue. 8 (August 2023)

Ruby Doley1 and Manoj Barthakur2*

1. North Gauhati College, Department of Botany, Guwahati, Assam – 781 031, India
2. B. Borooah College, Department of Botany, Guwahati, Assam – 781 007, India


Environmental contamination through aromatic hydrocarbons is a global concern among the scientific community. Environment is often polluted with monocyclic and polycyclic aromatic hydrocarbons through industrial discharges, accidental spills, gasoline, leakages, etc. Bacillus strains are commonly found in the soil and have outstanding potential to degrade such compounds to non-toxic or less toxic metabolites. This study aims to isolate, characterize and identify Bacillus strains from oil contaminated soil of Guwahati Refinery and to determine their potentiality to degrade monocyclic aromatic hydrocarbon: toluene and xylene. Out of 21 isolates, Bacillus subtilis designated as RD20 has shown significant biodegradation potentiality of these two mono-aromatic hydrocarbons and is thus selected for the present study. Biodegradation of compounds was determined through FTIR and GCMS studies. Detection of certain intermediate metabolites through GCMS suggested the degradation of the compounds by the bacterial strain. The metabolites obtained in toluene degrading pathway were identified as benzene acetic acid, 1,3-benzenediol, cyclopentane-1,2-diol, acetic acid, 2-propanol, butanoic acid, phthalic acid, hexanoic acid, propiolic acid, hexanedioic acid and propionic acid. However, the metabolites, such as benzene methanol (benzyl alcohol), cyclobutane carboxylic acid, phenol, formic acid, cyclopropane, acetic acid, phthalic acid, 1,3-cyclopentane carboxylic acid and succinic acid were obtained in xylene degradation pathway through GCMS study. Thus it has been found that the bacterial isolate transformed toluene and xylene into its relatively less toxic metabolites and therefore, Bacillus subtilis RD20 may be exploited as bioremediation agent of these two aromatic hydrocarbons.


Bacillus subtilis, Biodegradation, FTIR, GCMS, Toluene, Xylene, Metabolites, Monocyclic aromatic hydrocarbon


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