Jishna T., Shimna U., Shainy N.K., Shana Sherin C., Asha B. and Kunhi A.A.M. (2017). Isolation and characterization of Dimethyl phonol (2,6- and 2,3-xylenol) degrading bacterium from petroleum contaminated soil. In P.J. Jisha and K. Mashhoor (Eds.) ‘Advances in Microbiology’ LAP LAMBERT Academic Publishing, Saarbrucken, Germany, pp. 85-94 (ISBN: 978-3-330-07223-7).

Abstract

Biodegradation is the breakdown of complex and possibly toxic organic contaminants to non-toxic and simpler elements by microbial activity. Microorganisms have the capability of degrading all naturally occurring compounds. These contaminants can be considered as the food source or substrate. Biodegradation of any organic compound can be thought of as series of biological degradation steps ultimately results in the oxidation of the parent compound that often results in the generation of energy. Xylenols are naturally occurring phenolic compounds. There are six isomers of xylenol. The individual isomers are 2,4-xylenol, 2,3-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Together with cresols and cresylic  acid, xylenols are an important class of phenolics with great industrial importance. They are highly versatile compounds and are key raw materials in many different manufacturing processes as they possess high reactivity and solvency properties. Among the six isomers exist, 2,6-xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. 2,6-xylenol is used as raw material for antioxidant steriliser, herbicide, stai-profing agent, adhesive and foe fungicides. They are toxic to fish and aquatic invertebrates and care must be taken to prevent them from entering surface or ground waters.  

Present study aims to isolate di-methylated phenols (2,3-xylenol and 2,6-xylenol)-degrading microorganisms from petrol containing soil. Soil samples from various contaminated areas were collected and a mineral salt medium containing the substrates was inoculated with these soil samples. The organisms capable of growing in these medium were isolated. The growth of the organisms was acclimatised from 500 ppm to 100 ppm of substrate. the organisms that can grow at 1100 ppm concentration were isolated by spread plate method using mineral salt agar medium. the organism was identified by the biochemical tests. The utilisation of the substrate and increase in the biomass of the organism was estimated which proved the utilisation of the substrate by the isolated organism.