Preliminary investigation on multi metal tolerance of Bacillus thuringiensis isolated from industrial effluent soil

Abstract

Bacteria are considered as foremost bioremediating agents among microorganisms, encompassing simple biological mechanism to tolerate higher concentration of heavy metal and favoring conservative strategies to substitute the usage of chemicals. Relating this implication, the present study is designed to identify, screen and characterize bacteria from industrial site soil to tolerate multimetals. Almost 108 colonies were obtained at various concentrations (0.5–2.0 mM) of heavy metals (cadmium, nickel and lead) and were thrived in the reformed minimal media. Bacterial isolates that grown in the higher concentration of heavy metals (2.0 mM) were taken for further studies. Among ten bacterial colonies, one isolate was selected for each heavy metal and further screened for their multi metal tolerance. Isolate, C20 alone survived in heavy metal mixture fortified medium with high recovery rate and increased colony forming units. Molecular level characterization and phylogenetic tree analysis revealed that the isolate is identical to Bacillus thuringiensis. The study highlights that the multi metal tolerant B. thuringiensis could be used as an effective bioremediating agent to manage heavy metals particularly cadmium, nickel and lead in industrial area. Further, attributed to be a plant growth promoting rhizobacteria, this organism can promote dual stratagems as a bio remediating agent and fertility enhancer in agricultural field due to its dual functions.