Charu Vyas and Ashwini A. Waoo
Abstract
The cement industry significantly contributes to environmental pollution, particularly heavy metal contamination. Chromium, a highly toxic metal, is a major pollutant in cement plant soils. The selective pressure exerted by heavy metals can favor the growth of resistant/tolerant variants in the environment. Bioremediation using chromium-tolerant bacteria is a promising approach to mitigate heavy metal pollution. This research aimed to screen potential Cr degradersâ bacterial strains from the indigenous microbial community in cement plant soil at Satna, (M.P.) and differentiate the isolates for their heavy metal degrading/tolerating capability, i.e., assessing their bioremediation properties through various screening levels. The present study also employed three methods to determine the tolerance capacity of bacterial isolates to chromium: agar dilution method, gradient plate method, and minimal inhibitory concentration (MIC). The study also attempted to investigate the comparative analysis among the three methods. The results showed that all the bacterial isolates showed negligible or no colonial growth at the same chromium concentration in all three methods. However, the MIC method was the most accurate in detecting chromium tolerance. Based on their minimum inhibitory concentrations (MIC) and maximum tolerance concentrations (MTC), seven chromium-tolerant strains were chosen from the small number of bacterial isolates isolated from the soil. Different levels of chromium tolerance were shown by the MIC values, which varied from 15 to 33 mg/l. The most tolerant strains, PCN-P1/1/Cr and PCN-P1/2/Cr, showed a MIC of 31 mg/l and were selected for further research. The findings of this study demonstrate the potential of chromium-tolerant bacteria isolated from cement plant soil for bioremediation applications.