Abstract

There is a growing interest in the bio-application of microorganisms from the gut of earthworms on the bio-transformation of persistent and toxic pollutants during vermifiltration. Earthworms harbor beneficial microbes in their gut which symbiotically aid in biodegradation of pollutants in their drilosphere. Dichlorodiphenyltrichloroethane (DDT) is an example of polychlorinated hydrocarbons and metabolites thereof that are persistent in the environment and are toxic to humans and animals. This study aimed at isolating and identifying 4,4 DDT degrading microorganisms in the gut of Eisenia fetida acclimatized to sewage. Five pure isolates obtained from gut contents were cultured in MSM supplemented with 15 mgL-1 DDT followed by glucose yeast extract agar sprayed with 1% 4,4 DDT in ether (v/v). Two pure isolates positive for 4,4 DDT biodegradation were inoculated on MSM containing 15 mgL-1 4,4 DDT. The resulting metabolites were identified using Gas Chromatography. The positive isolates were identified using 16S rRNA gene analysis as belonging to the Rhodococcus genus and the Bacillus genus, exhibiting 88.36% and 85.22% 4.4 DDT degradation respectively. The study demonstrated DDT-degradation by bacteria from the gut of E. fetida. These findings can be useful in optimization of vermifilters for biodegradation of DDT and other xenobiotics.

Authors and Affiliations