一株新型Lysinibacillus fusiformis菌株G5M11b对Cr(Ⅵ)的还原性能研究

Reductive capability of a novel Lysinibacillus fusiformis strain G5M11b on Cr(Ⅵ)

为了筛选对Cr(Ⅵ)有强耐性的菌株,并确定其最佳还原条件,通过驯化、筛选后得到耐铬菌株,利用形态特征、16S rDNA序列测定对其进行鉴定,进而建立响应曲面模型分析温度、pH值、质量分数对菌株还原效果的影响。结果显示,菌株与纺缍形赖氨酸芽孢杆菌(Lysinibacillus fusiformis)G5M11b型系统发育关系接近,将其命名为LfCr6,菌株的最佳还原条件温度为27.42℃,pH值为6.78,菌株质量分数为4%。通过响应曲面模型预测出该菌对100 mg/L Cr(Ⅵ)的还原率可达80.2%。这表明LfCr6菌株可以耐受高质量浓度Cr(Ⅵ)且具有良好的Cr(Ⅵ)还原能力。该菌株为微生物修复Cr(Ⅵ)污染环境提供了可能的菌种资源。

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 G5M11b,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.