Isolation and identification of naturally occurring textile effluent-degrading bacteria and evaluation of their ability to inhibit potentially toxic elements

Untreated textile dye-contaminated wastewater contains potentially toxic elements (PTEs) and causes pollution when discharged. Herein, we attempted to isolate and identify naturally occurring effluent-degrading bacteria and investigate their resistance potentials against various PTEs. Wastewater samples were collected from the biological effluent treatment plant of a textile dyeing industry located at the Chattogram Export Processing Zone, Bangladesh. The effluent samples contained Pb and Cr, with 27 times higher Cr content than the regulatory limit. A total of 14 bacterial isolates were isolated from the effluent based on differences in their cultural properties. Based on morphological and biochemical features, isolates were identified as Staphylococcus xylosus, Bacillus korlensis, Pseudomonas fluorescens, Pseudomonas cichorii, Brevundimonus diminuta, and Enterococcus columbae. Isolates were primarily screened for their ability to reduce the content of PTEs, such as Cr, Pb, Mn, Cu, and Cd. Pre-incubation of effluents and isolates revealed that most bacteria reduced the PTEs in the effluent. Of the 14 isolates, six exhibited potential in reducing most of the PTEs-Cd (94-99%). Further, Cr was decreased by 68 and 61% in the presence of S. xylosus and P. fluorescens, respectively, after 72 h of incubation in a medium containing 400 mg L-1 salt. The findings of this study can provide insights into the efficient biological remediation of PTEs in industrial wastewater.