Bacterial Diversity In The Soils Of Inexpressible Island,Antarctica

Objective: To reveal the structure and diversity of bacteria communities in the five soil samples from Inexpressible Island,Antarctica.Analyzing the relation between environmental factors and uncultured bacterial taxa.To provide reference value for the ecosystem research in this area,at the same time,to lay the foundation for the development of the bacterial resources and screen strains that produce bioactive substances in Antarctic soils.Method:1.Three different cultivation methods were applied to isolate bacteria in the five soil samples,including directly spreading,microaerobic enrichment and aerobic enrichment method.The isolates were identified by 16 S r RNA gene sequencing,and phylogenetic trees were constructed to study the diversity of culturable bacteria.2.On the basis of Illumina MiSeq high-throughput sequencing after DNA extraction from environmental samples,bioinformatics analysis was performed on high-quality sequencing data to obtain bacterial community structure information in the soil.Results:1.A total of 144 bacteria strains were isolated from five soil samples by three different methods.The results indicated that culturable bacteria in the soil of the region were distributed in Actinobacteria,Firmicutes,Proteobacteria,Deinococcus-Thermus and Bacteroidetes at the phylum level.Different soils habored different culturable bacteria at the level of phylum and genus.Bacillus dominated in soil from Penguin activity area.Pseudomonas and Streptomyces dominated in soil from mosses and lichens coverage area.Psychrobacter dominated in lakeside soil,with Flavobacterium and Chryseobacterium were isolated only in this sample.Actinobacteria were dominant in dry soils,such as Pseudarthrobacter,Rhodococcus and Microbacterium were isolate only from dry soil samples.It was suggested that 24 isolates were found to be potential novel species among culturable strains,there are many strains belong to Actinobacteria at the phylum level.The ability of these strains to produce secondary metabolites could be investigated later,such as antibiotics.2.The result revealed that there were abundant bacterial communities in the soil by using Illumina Miseq high-throughput sequencing method.A total of 610 OTUs obtained and many bacteria were not isolated by culture method.The results showed that the bacteria mainly divided into Actinobacteria,Firmicutes,Proteobacteria,Verrucomicrobia,Bacteroidetes,Cyanobacteria,Planctomycetes,Gemmatimonadetes,Acidobacteria and Chloroflexi at the phylum level.Actinobacteria were the predominant phylum of them.Firmicutes was abundant in the soils from Penguin activity area,with Gottschalkia,Atopostipes and unclassified Gemmatimonadetes(OTU7)were dominate in it.Unclassified Cyanobacteria genus(OTU153)were dominant in the mosses and lichens coverage area.Unclassified Gemmatimonadaceae(OTU249),Singulisphaera and Flavobacterium dominated in fresh lakeside soil.In the soil from typical geological zone and biologically scarce background zone,Actinobacteria dominated in this dry gravel type soil,and Crossiella and Pseudonocardia were abundant in this soil.The bacterial diversity was affected by different soil environments,and this indicated that animal activities could affect the bacterial community structure significantly.Conclusion: There are exploitable bacterial resources in the soil of Inexpressible Island,Antarctica.This study also provides some basic data for the study of bacterial diversity in Antarctic soils.The dominant bacterial communities in the soil are affected by a variety of environmental factors,which provide an experimental basis for isolating strains with application value.