Reductive capability of a novel Lysinibacillus fusiformis strain G5M11b on Cr(Ⅵ)
In a bid to explore the potential of bioremediation technology in engineering,the author investigated the use of chromium-reducing bacteria for remediating hexavalent chromium in soil.Soil samples were collected from a chemical site in Shenyang.Following continuous culturing,a strain capable of reducing Cr(Ⅵ)was isolated.Results indicated that the strain bore close phylogenetic resemblance to Lysinibacillus fusiformis G5Mllb,sharing a 98％homology,and was identified as Lysinibacterium spinosine,ultimately named LfCr6.Various factors exhibit differing impacts on the Cr(Ⅵ)reduction activity of the LfCr6 strain.The study analyzed the effects of temperature,pH,and quality score on the optimal reduction performance of Lysinibacterium spinosine,encompassing the following findings:(1)The strain's reduction rate gradually increases within the temperature range of 10-25℃,and generally,LfCr6 demonstrates effective Cr(Ⅵ)reduction in solutions at temperatures of 20-30 ℃;(2)Optimal reducibility to Cr(Ⅵ)is observed at pH values ranging from 6 to 7;(3)The best reduction effect of LfCr6 is achieved at a quality score of 4％,yielding a reduction rate of 69.97％.Based on the analysis results obtained from Design-Expert V8.0.6,the model predicts a microbial heavy metal reduction rate of up to 80.4％.The corresponding optimal conditions are determined to be 27.42 ℃,pH 6.78,and an inoculation amount of 4％.These values closely align with the data predicted by the model,and all three optimal conditions fall within the predicted optimal response range.This suggests that the model effectively captures the influence of the three main factors(A,B,and C)on the heavy metal reduction rate.The close alignment between the predicted value of the model and the experimental results suggests the model's effectiveness in predicting the absorption conditions outlined in this study.Consequently,the response surface model obtained through BBD experimental design can adeptly represent the microbial heavy metal reduction rate test by optimizing temperature,pH,and quality score to enhance the reduction rate of microbial heavy metals.The findings indicate that the LfCr6 strain exhibits a high tolerance for elevated concentrations of Cr(Ⅵ)and demonstrates robust Cr(Ⅵ)reducing capabilities,thus presenting a potential microbial resource for remediating Cr(Ⅵ)contamination.
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