铀尾矿堆中优势菌的分离鉴定及其耐铀性研究

从广东省韶关市某露天铀尾矿堆中筛选分离出一株优势菌株,通过形态观察和16S rDNA基因测序比对,初步鉴定该细菌为苏云金杆菌(Bacillus thuringiensis,简称Bt)。研究了环境条件因素(温度、pH值、盐浓度)对该细菌繁殖增长的影响及其对铀的耐受性。通过生长特性研究确定该细菌的最适生长温度为30℃,pH=7.0,盐度适应范围为0.5~60 g/L。对铀的耐受性实验表明:在接种量为25%(体积分数),初始pH为4.0~10.0和温度为30℃条件下,该菌在铀初始浓度为100 mg/L,NaCl质量浓度为8%以内可保持良好的生长能力。研究结果显示,该细菌对铀具有良好的耐受性,表明其在铀的浸出及铀污染土壤的生物修复方面有潜在的应用前景。

ISOLATION AND IDENTIFICATION OF A DOMINANT BACTERIA STRAIN FROM A URANIUM MILL TAILING PILES AND ITS URANIUM-TOLERANT PERFORMANCE

A strain of dominant bacteria was isolated from a uranium mill tailing piles located in Shaoguan city，Guangdong province，China． The bacteria was identified as Bacillus thuringiensis ( named Bt) on the basis of its colony morphology， physiological and biochemical characteristics，as well as 16S rDNA sequence homology analysis． Its uranium tolerance and the effect of different conditions ( temperature，pH value，NaCl concentration) on its growth were evaluated through batch experiments in the presence of 5 mg /L U6 + liquid culture through analyzing the value of D600 nm ． The results of single factor growth character experiments indicated that the optimum temperature，pH and salinity range for growth were 30 ℃，pH = 7. 0， and 0. 5 ～ 50 g /L( NaCl) ，respectively． The strain could tolerate a uranium concentration up to 100 mg /L U6 + at 25% incubation amount，30 ℃，initial pH 4 ～ 10，and it could preserve high growth activities in the salinity less than 8%． The results indicated that Bt strain has high resistance to uranium and has potential in application for bioleaching of uranium and bioremediation of uranium-polluted soil．