A Rice Rhizosphere-Associated Bacillus sp. With Dual Biosorption and Enzymatic Pathways for Chromium (VI)
Arup Kumar Sarkar1, Soumita Roy1, Nilakshi Chakraborty1
1Plant Physiology and Molecular Biology Research Unit, Department of Botany, University of Kalyani, Kalyani, India.
Journal of Basic Microbiology
|April 27, 2026
Summary
This study highlights Bacillus sp. AKS_bp1, a plant growth-promoting rhizobacterium, effectively detoxifies hexavalent chromium (Cr(VI)). The bacterium demonstrates high Cr(VI) tolerance, biosorption, and Cr reductase activity, aiding in bioremediation of contaminated industrial effluents.
Area of Science:
- Environmental Microbiology
- Bioremediation
- Plant-Bacterial Interactions
Background:
- Hexavalent chromium (Cr(VI)) is a hazardous pollutant that impairs soil health and plant development.
- Bioremediation using plant growth-promoting rhizobacteria (PGPR) offers a sustainable solution for heavy metal contamination.
Purpose of the Study:
- To investigate the Cr(VI) detoxification capabilities of Bacillus sp. AKS_bp1.
- To evaluate its potential for bioremediation of Cr(VI)-contaminated industrial effluents and its impact on plant responses.
Main Methods:
- Isolation and characterization of Bacillus sp. AKS_bp1 from rice rhizosphere.
- Laboratory studies on Cr(VI) tolerance, biosorption kinetics, and Cr reductase activity.
- Analysis of functional groups involved in Cr binding using FTIR and SEM.
- Assessment of antioxidative enzyme activity and plant responses under Cr(VI) stress.
- Application of the strain in tannery effluent treatment.
Main Results:
- Bacillus sp. AKS_bp1 exhibited high tolerance to Cr(VI) and achieved ~80% Cr(VI) reduction with 95.21% biosorption capacity within 72 hours.
- FTIR and SEM confirmed the presence of hydroxyl, polysaccharides, and amino-nitrogen groups for Cr binding.
- Cr reductase activity was observed and validated under various conditions (pH, temperature, metal/salt presence).
- The strain upregulated antioxidative enzymes, mitigating Cr-induced toxicity and reducing lipid peroxidation and polyphenol oxidation.
- Application of Bacillus sp. AKS_bp1 removed 36.86% of Cr(VI) from tannery effluent in 72 hours.
Conclusions:
- Bacillus sp. AKS_bp1 is a potent PGPR with significant Cr(VI) detoxification and bioremediation potential.
- The bacterium effectively removes Cr(VI) from industrial effluents and protects plants from Cr-induced oxidative stress.
- This strain offers a sustainable approach for bioremediation of Cr(VI) and other toxic metals, promoting crop growth.
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