Bioremediation Potential of Chromium-Resistant Paenibacillus taichungensis Strain MAHA-MIE: Optimization and Characterization Studies
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Abstract
Aim: This study investigated the bioremediation potential of P. taichungensis strain MAHA-MIE- Cr(VI)-resistant bacterium, through systematic screening, biochemical and molecular characterisation, and optimisation of operational conditions.
Methods: The approach involved isolating and identifying Cr(VI)-resistant bacteria through 16S RNA sequencing, followed by optimisation of hexavalent chromium Cr(VI) bioreduction using response surface methodology integrated with artificial neural network (RSM–ANN) modelling. The effects of three independent variables: nutrient broth concentration, pH and Cr(VI) concentration on bioreduction efficiency were examined.
Results: Among thirty-one Cr(VI)-resistant isolates obtained from contaminated soil, strain Cr-RB18 exhibited the highest Cr(VI) reduction capacity. Biochemical analysis characterised the isolate as Gram-variable, facultatively anaerobic, motile, catalase-positive, capable of hydrolysing starch and producing H₂S. Molecular identification confirmed it as P. taichungensis strain MAHA-MIE. Under ANN-optimal conditions—9.56 g/L nutrient broth concentration, pH 6.48, and 69.57 ppm Cr(VI), the strain achieved a maximum Cr(VI) reduction of 99.17%. The model exhibited excellent predictive accuracy, with R² = 0.99, RMSE = 1.00, SEP = 1.56%, and RPD = 0.63%.
Conclusion: These findings highlight strain MAHA-MIE as a promising candidate for bioremediation of Cr(VI)-contaminated environments, warranting further investigation for field-scale application.