Cr(VI)还原菌的筛选、鉴定及其还原物质分析

Screening and identification of Cr(VI) reducing bacteria

【背景】铬污染土壤是我国土壤污染修复的重点治理对象,在众多修复技术中,微生物法因具有简单、经济、无二次污染等特性已成为研究热点,而微生物法中筛选出既能适应污染场地环境又能高效还原Cr(VI)的菌株尤为重要。【目的】筛选适应西北寒旱区高效还原Cr(VI)的菌株,丰富铬还原菌资源库,为铬污染土壤修复奠定基础。【方法】采用富集驯化、分离纯化法进行筛菌;通过形态学和分子生物学相结合的方法对目的菌株进行鉴定;采用傅里叶变换红外光谱法对还原机理进行研究。【结果】菌株G-13有较强的Cr(VI)还原能力,pH 9.0、温度为30°C条件下,60 h对Cr(VI)(100 mg/L)的还原率达到82.8%。经形态学和分子生物学鉴定,菌株G-13为Micrococcus luteus。反应中Cr(VI)的降低伴随着Cr(III)的增加,说明以还原反应为主,并且还原能力与细菌生长呈依赖型关系。对细胞各组分及变性研究表明,胞外酶在还原反应中占主要作用。除Pd2+、Cd2+外,其余金属离子对酶活性无明显抑制作用。通过傅里叶变换红外光谱分析,发现G-13与Cr(VI)结合位点主要为羟基、羰基、羧基、–CH、酰胺基等。【结论】菌株G-13有较强的Cr(VI)还原能力,能为西北寒旱区铬污染土壤修复丰富菌种资源。

[Background]Chromium-contaminated soil is a key target for soil pollution remediation in China.In many remediation technologies,microbial method has become a research hotspot because of its simple,economical,and no secondary pollution.It is particularly important to screen strains that can adapt to the polluted site environment and efficiently reduce Cr(VI)in the microbial method.[Objective]Screening strains adapted to the efficient reduction of Cr(VI)in cold and arid regions of Northwest China,enrich the resource pool of chromium reducing bacteria,and lay the foundation for remediation of chromium-contaminated soil.[Methods]Screening bacteria by enrichment,domestication,isolation and purification;the target strain was identified by a combination of morphology and molecular biology;and the reduction mechanism was studied by fourier transform infrared spectroscopy.[Results]G-13 has strong Cr(VI)reducing ability.At pH 9.0 and temperature 30°C,the reduction rate reached 82.8%in a 100 mg/L Cr(VI)solution within 60 hours.Morphological and molecular biological identification showed that the strain G-13 was Micrococcus luteus.The decrease of Cr(VI)in the reaction was accompanied by the increase of Cr(III),which indicated that the reduction reaction was the main factor,and the reducing ability was dependent on the growth of bacteria.Studies on cell components and denaturation showed that extracellular enzymes play a major role in the reduction reaction.Except for Pd2+and Cd2+,the other metal ions had no significant inhibitory effect on enzyme activity.Through fourier transform infrared spectroscopy analysis,it was found that the binding sites of G-13 and Cr(VI)were mainly–OH,C=O,-COOH,-CH,–CONH2 and so on.[Conclusion]G-13 has strong Cr(VI)reducing ability,and can be used to rich bacterial resources for repairing chromium-contaminated soil in northwestern cold and arid regions.