Halotolerant Co-Cultured Bacterial Strains used in Degradation of Tannin Isolated from Tannery Industry Contaminated Sites

Abstract

The residual tannins discharged from tanning units of the leather industry have an adverse effect on living organism and causes serious environmental pollution. Biological degradation is an important mechanism of organic chemical removal in natural systems owing to its environmental compatibility. But in extreme environment like high salinity of tannery effl uent, the effi ciency of degradation by microorganisms would be exceptionally low. Therefore halotolerant microbes would play a signifi cant role in biodegradation of tannins. This study aims at isolating and identifying strains of halotolerant cocultured bacteria able to degrade tannin from soil samples contaminated by tannery industry, in order to use such bacteria for the bioremediation of contaminated sites. The bacterial isolates have been characterized by biochemically and molecularly through 16S rRNA sequencing, and identifi ed as Bacillus amyloliquefaciens and Bacillus polyfermenticus, this latter being able to degrade 92% of tannin (200 mg/L) compared to B. amyloliquefaciens. The variables (salinity, carbon and nitrogen sources) affecting the process of tannin degradation have been optimized.