云南个旧锡矿区可培养细菌多样性及其重金属抗性

Diversity and heavy-metal tolerance of bacteria isolated from Gejiu tin mining area of Yunnan

【目的】揭示个旧锡矿区尾矿库和矿坑土壤中可培养细菌的多样性;发掘一批锡矿区土壤细菌菌株并对其Pb2+、Cd2+耐受性进行评价。【方法】采用纯培养法和基于16S rRNA基因序列的系统发育分析对样品中可培养细菌多样性进行研究,平板法评价代表菌株对Pb2+、Cd2+的耐受性。【结果】使用2种培养基从尾矿库和矿坑土壤中分离到214株细菌,对其中107株代表菌株的16S rRNA基因序列系统发育分析结果显示,菌株分属细菌域的5个门、12个目、25个科、42个属;其中变形菌门(Proteobacteria)是优势类群,占总菌株数的69.2%;假单胞菌属(Pseudomonas)菌株是优势物种,占24.8%;2株菌代表了2个潜在新类群。对105株代表性菌株的重金属耐受性研究表明,耐受浓度1000 mg/LPb2+或Cd2+的菌株分别占73.3%和8.6%,菌株对Pb2+的耐受性明显好于Cd2+;分离自锡尾矿库的菌株耐受不同浓度Pb2+和Cd2+菌株比例明显高于矿坑来源的菌株;分离自锡尾矿区的2株菌(DT47-2A和DT50-1)对1000 mg/L浓度Pb2+和Cd2+均具耐受性。【结论】个旧锡矿区土壤可培养细菌具有丰富的多样性,而且蕴含着不少潜在新类群;该环境中含有大量Pb2+、Cd2+耐受菌株,并对Pb2+、Cd2+具有较强的抗性或适应性。

[ Objective] We assessed the cuhurable bacterial diversity in tin mine area in Gejiu, Yunnan, China, and heavy-metal tolerance of the isolated bacteria. [ Methods] Bacterial strains were isolated from the samples by using the culture-dependent method and investigated by using phylogenetic analysis based on 16S rRNA gene sequence comparisons. Representatives of isolates were selected to detect their tolerance against heavy metals of Pb2＋ and Cd2 ＋ . [ Results] We isolated 214 bacterial strains from soils by using two media. Based on colony characteristics, we selected 107 representatives of strains for phylogenetic analysis based on 16S rRNA gene sequences. Results showed that 107 isolates belong to 42 genera of 25 families of 12 orders in 5 phyla. The most abundant isolates were within the phylum Proteobacteria （69.2%） and the genus Pseudomonas （24.8%）. Among the 107 isolates, at least 2 strains should represent 2 potential novel species. One hundred and five strains were selected to investigate heavy-metal tolerance and results showed that 73.3% and 8.6% isolates could grow under 1000 mg/L P Cd2＋and Pb2＋, respectively. Most strains were more sensitive to Cd2＋ than Pb2＋. Isolates from tin mine tunnel adit were more sensitive to Cd2＋ or Pb2＋ than those from tin tailings area. Moreover, 2 strains （ DT47-2A and DTS0-1 ） can grow under both 1000 mg/L Cd2＋ or Pb2＋. [ Conclusion] There is abundant bacteria as well as source of novel taxa in Gejiu tin mining area. Most of them had the ability of high resistance against heavy-metal Cd2＋ or Pb2＋.