Novel Bacillus Consortium for Degradation of 2,4- Dinitrotoluene: A Xenobiotic Compound

Abstract

The xenobiotic compound 2,4-Dinitrotoluene (DNT) is used in the production of explosives (2,4,6-Trinitrotoluene,TNT), polyurethane/dyes, and in smokeless gunpowder. The cleanup of these compounds has gained much attention in the last decades due to hazardous nature of these compounds. Numerous bacterial strains capable of growing on DNT as the sole source of carbon, nitrogen and energy have been isolated by various scientists. Attempts to degrade DNT at high concentrations have never been found successful. The present study was conducted in Amity Institute of Microbial Biotechnology, Amity University between June 2010 and July 2011. About 18 bacterial cultures were isolated from the contaminated sites in the presence of 0.001% (w/v) 2,4-DNT.Isolated strains were further screened on the basis of their tolerance towards 2,4-DNT by growing them in the presence of 0.001% to 0.03% (w/v) 2,4-DNT. Out of 18 strains, eight tolerated varying concentration of 2,4-DNT and were mixed in different permutation & combination for preparation of microbial consortia. The best consortium (No.4 with strains RSE165, RSA32, RSB80 and RSD127) was selected and subjected to molecular characterization. Bacterial strains used in this study were identified as Bacillus subtilis RSE165 (NCBI accession no. JQ887982), Bacillus megaterium RSA32 (KR051485), Bacillus cereus RSB80 (JQ040533) and Bacillus flexus RSD127 (KR051486).The analysis of the 2,4-DNT degradation capabilities of the best four individual strains and their consortium by GC analysis shows that the spectral peak of 2,4-DNT is completely replaced by three small peaks which indicate its utilization and degradation by the bacterial strains as well as by their consortium.