Hexavalent chromium reduction by bacteria from tannery effluent.

Area of Science:

• Environmental Microbiology
• Bioremediation
• Toxicology

Background:

• Hexavalent chromium (Cr(VI)) is a toxic industrial contaminant.
• Bioremediation using chromium-reducing bacteria offers a sustainable solution.
• Understanding bacterial Cr(VI) reduction mechanisms is crucial for effective detoxification.

Purpose of the Study:

• To isolate and identify a bacterial strain capable of reducing Cr(VI).
• To investigate the influence of environmental factors on Cr(VI) reduction by the isolated strain.
• To evaluate the strain's potential for Cr(VI) detoxification in industrial wastewater.

Main Methods:

• Isolation and identification of chromium-reducing bacteria using 16S rRNA gene sequencing.
• Optimization of Cr(VI) reduction by studying parameters like temperature, Cr concentration, mobility, and carbon sources.
• Assessment of Cr(VI) reduction in artificial and industrial sewage water.
• Microscopic analysis (SEM, TEM) and reductase assays to elucidate the reduction mechanism.

Main Results:

• An indigenous strain, Ochrobactrum intermedium Rb-2, was identified.
• The bacterium effectively reduced Cr(VI) under various tested conditions.
• Cr(VI) reduction was an inductive enzymatic process, not due to cell membrane permeability changes.
• Chromium precipitates were observed on bacterial surfaces and within cells.

Conclusions:

• Ochrobactrum intermedium Rb-2 is a robust Cr(VI)-reducing bacterium.
• The strain demonstrates significant potential for Cr(VI) bioremediation in diverse environments.
• This bacterium can be utilized for effective detoxification of hexavalent chromium in industrial effluents.