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

Abstract:

Abstract:［Objective］We assessed the culturable 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 Pb2+ and Cd2+ ，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 DT50-1) can grow under both 1000 mg/L Cd2+ and 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+ ．

Key words:Keywords: tin mining area，culture-dependent method，bacterial diversity，16S rRNA gene homology，heavy-metal