Lead biosorption by Bacillus tequilensis FB-6: characterization of resistance mechanisms and its potential for remediation of contaminated soil.
Background: Lead (Pb) contamination in agricultural soils poses significant threats to food safety and environmental sustainability. Microbial bioremediation offers a sustainable solution, yet the mechanisms underlying microbial Pb tolerance and immobilization remain insufficiently explored. This study investigates the Pb resistance and adsorption characteristics of Bacillus tequilensis FB-6, a strain isolated from a Pb-contaminated site.
Results: B. tequilensis FB-6 displayed a high Pb2+ tolerance, with a minimum inhibitory concentration of 2200 mg L-1, and exhibited cross-resistance to other heavy metals including Mn2+ and Cu2+. Microscopic and spectroscopic analyses indicated that Pb2+ binding was facilitated by extracellular polymeric substances (EPS), particularly polysaccharides, and that Pb2+ was converted into the insoluble mineral Pb9(PO4)6. Enzyme activity assays revealed an increase in superoxide dismutase activity (15.5-47.5%) and a corresponding decrease in dehydrogenase activity (5.7-49.1%) under Pb2+ stress, suggesting oxidative stress response mechanisms. In plant co-cultivation trials, root inoculation with B. tequilensis FB-6 significantly reduced Pb uptake and enhanced growth performance, indicating its potential to mitigate Pb bioavailability in soil.
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The Journal of the Science of Food and Agriculture publishes peer-reviewed original research, reviews, mini-reviews, perspectives and spotlights in these areas, with particular emphasis on interdisciplinary studies at the agriculture/ food interface.
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