具重金属抗性产酸菌的分离及生物学特性研究

Study on Isolating of the Strain Having the Ability of Heavy Metal Resistance and Producing Organic Acid

铅锌冶炼厂周边区域遭受复合重金属的严重污染,目前单一重金属污染土壤的修复技术比较成熟,而针对复合重金属严重污染土壤的治理技术有待进一步研发。本研究采集铅锌冶炼厂附近重金属污染土壤,试图从土壤中分离出具重金属抗性的产酸菌,并应用于浸出修复复合重金属重污染土壤。通过野外取样调查、分子生物学鉴定和显微镜观察等分析测试手段,从铅锌冶炼厂附近土壤中成功分离出一株具强重金属抗性的产酸菌,经鉴定为黑曲霉(Aspergillus niger),命名为F2。对其重金属抗性和浸出修复能力进行研究,结果表明:黑曲霉F2对Pb、Zn、Cd和Cu的最大耐受质量浓度分别为8 500、6 000、2 200和2 500 mg·L^(-1)。在高浓度重金属的胁迫下,培养前期菌株处于驯化阶段,不生长或生长很慢,培养后期生长速度加快。将黑曲霉接种到50 mL培养液中培养7 d,培养液的pH值从7.00降至2.40,将2.5 g灭菌土壤加入50 mL培养液中,接种1mL菌液,置于恒温振荡培养箱中(温度28℃、转速120 r·min^(-1))培养15 d,Pb、Zn、Cd和Cu的浸出百分率分别为46.79%、52.01%、29.40%和75.70%,对4种重金属的总浸出率达59.54%。由此可见,黑曲霉不但具有很强的重金属耐受性,还具有较大的浸出修复重金属污染土壤的潜力,具备一定的研究价值。

The soil in the surrounding area of Pb/Zn smeltery was contaminated by heavy metals such as Pb, Zn, Cd and Cu et al. The remediation technology for single heavy metal contaminated soil is already mature, but it needs further development for the seriously heavy metals compound contaminated soil. In the paper, the soil was collected in the surrounding area of Pb/Zn smeltery, and the microbiology having not only the ability of heavy metal resistance but also the ability of producing acid would be selected and isolated in order to being used to remedy the contaminated soil. Through field sampling and surveying, molecular biological identification, microscopic examination, a strain was selected from the soil samples which was indentified as Aspergillus niger and named as F2, the ability of heavy metal resistant and bioleaching remediation was studied in the paper. The results show: The largest concentration of resistance to Pb, Zn, Cd and Cu of Aspergillus niger F2 is 8 500, 6 000, 2 200 and 2 500 mg·L-1, the largest concentration of resistance to the compound of Pb, Zn, Cd and Cu is 105, 2 400, 2 200 and 2 400 mg·L-1. The growth of Aspergillus niger F2 on LB medium containing high concentrations of heavy metals was faster in the later stage than in the early stage. The pH value of liquid medium was degraded from 7.00 to 2.40 in 7 days. 2.5 g sterilized soil was added into 49 mL liquid medium, 1 mL spore suspension liquid was inoculated, then put in 28 ℃ and 120 r·min-1orbital shaker incubator, after 15 days, the bioleaching efficiency of Pb, Zn, Cd and Cu was 46.79%, 52.01%, 29.40% and 75.70% respectively, the total bioleaching efficiency of Pb, Zn,Cd and Cu was 59.54%. Thus Aspergillus niger F2 has large ability of heavy metal resistance and good applied value of bioleaching remediation on heavy metal contaminated soil.