| Over-exploitation of mineral resources has caused serious harm to the environment.Bioremediation of heavy metal contaminated soils is a new in-situ remediation technologies,which attaches more and more attention.It is low environmental impact,high efficiency and low cost in environmental pollution.Microorganisms can fix,mobile or transfer heavy metals in the soil,in order to reduce its toxicity to environment,so as to achieve the purpose of bioremediation.This paper selects ramie rhizosphere soil from mining area Zhuzhou,Hunan province as research subjects.Further research on microbial resource and biodiversity in heavy metal contaminated area will farther understand the microorganisms in ramie rhizosphere soil,enrich microbe resource,clarify the relationship between diversity and Bioremediation of heavy metal,and can obtain heavy metal-resistant Bacteria,offer the theoretical and experimental basis for restoring polluted soils with heavy metals.The main contents of this article includes the following two parts:(1)The bacterial diversity of ramie rhizospheric soil around mine refineryGather ramie root from Zhuzhou mine and collect soil roots,total DNA from the soil was extraction.Ribosomal 16S rDNA genes were amplified using the universal bacterial primers 27F and 1492R.Cleaned PCR products were ligated into the pMD18-T easy vector,and introduced into competent Escherichia coli.Sixty operational taxonomic units from the 16S rDNA root soil clone library were identified based on sequence analysis to 97 individual sequences screening.Phylogenetic analysis revealed that the majority of clones were affiliated with the classes Proteobacteria(43.30%,270TUS),which included a(8.24%,60TUs),P(20.61%,20OTUS),y(11.34%,11OTUs),?(3.09%,30TUs)subclasses,Planctomycetia(3.09%,30TUS),Verrucomicrobia(4.12%,20TUS),Gemmatimonadetes(18%,10OTUS),Bacteroidetes(2.06%,20TUS),Actinobacteria(12.37%,10OTUS),Acidobacteria(6.19%,5 OTUS),Anaerolineae(2.06%,1OTUS),Firmicutes(1.03%,1OTUS),uncultured bacteria(8.25%,70TUs).The results showed that the most abundant among the classes was Proteobacteria,What follows are Gemmtimonadetes and Actinobacteria.Most of the clones have low 16SrDNA gene sequence similarity with the genebank bacteria.We suggest the presence of heavy metals in mining area can lead to changes in microbial gene.We found that many bacteria have the ability of anti-heavy metal,another indication that mang new rhizosphere community exist in the ramie rhizospher soil in order to better fit in and which have further development and utilization.(2)Isolation,identification and environmental adaptability of heavy metal-resistant BacteriaIn order to understand the microorganisms in ramie rhizosphere soil around mine refinery,6 bacteria strains were concentrated and isolated by being cultured with Cd2+ stress.The strains were numbered with JJ1(Chryseobacterium indoltheticum)?JJ2(Cupriavidus oxalaticus)?JJ10(Pseudomonas_helmanticensis)?JJ11(Bacillus mycoides)?JJ15(Bacilluss almalaya)and JJ18(Acietobacter tjernbergiae).Sequence alignment and phylogenic analysis showed that 3 strains were grouped into Proteobacteria,2 strains were grouped into Firmicuts and 1 was grouped into Flavobacteria.The tolerance ability for all the strains was the trend of Pb2+>Zn2+>Cu2+>Cd2+,the maximum tolerance concentration for Cd2+ was 200 mg/L,for Pb2+ was 1600 mg/L,for Zn2+ was 600 mg/L,and for Cu2+ was 265 mg/L,which demonstrated that all the stains had high resistance ability to the heavy metals.Other influential factors including pH and salinity were experimented to determine the environmental adaptability for the strains.The results of heavy metal resistance,pH and salinity showed that JJ1,JJ10 and JJ15 had high environmental adaptability,and might be as candidate microorganisms to study on restoring polluted soils with heavy metals. |
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