| Polar regions are located in the highest latitude of the world,with characteristics of low temperature,barren nutrition,drought,few vegetation and animals.But there is still high bacterial diversity,containing rich metabolic diversity cold-adapted regulatory mechanism,low energy environmental survival mechanism and other unknown huge significance.As a result,the polar are a treasure containing rich microbial resources.This research collected some different types samples from the polar environment and improved laboratory's cultured bacterial isolation methods and using 16S rDNA high throughput sequence method to analyze the diversity of culturable and uncultured bacteria and their potential values.Finally,Some bacteria with antibacterial ability were screened out from cultured bacteria and three novel strains were identified by multiple classifications.The samples including tundra soil samples collected from the Ny-Alesund region of Arctica(July and August in summer),surface marine sediment near the gulf,soil samples and fresh water samples collected from the Field Peninsula and the Unutterable Island of Antarctica(January and February in summer).On the culture conditions including temperature,time,concentration of nutrition was modified to 4 ? and 15 ?,15 to 30 days,dilute R2A medium to 10-30%,relatively.As a result,a total of 1,220 strains of bacteria were isolated,including 615 strains isolated from arctic tundra soil samples,103 strains isolated from arctic sediment samples,278 strains isolated from Antarctic field peninsula soil samples,139 strains isolated from Antarctic freshwater samples,and 85 strains isolated from Antarctic Unutterable Island soil samples.These bacteria are distributed on the level of phylum:Proteobacteria,Actinomycetes,Bacteroidetes,Firmicutes,and Deinococcus-Thermus.We found that dominant bacteria have many specific fuctions,such as resistance to ultraviolet radiation,survival strategy in low energy environment,promoting plant's assimilation of nutrition,antimicrobial substance and survival strategy in low temperature,which have important improving values in fields of agriculture,industry,medicine.Due to the limited amount of samples collected,this study only conducted 16S rDNA high-throughput sequencing from 8 soil samples in the Field Peninsula of Antarctica(near the Great Wall station of China).The results showed that among the 536,890 sequences obtained by sequencing,about 90%of the bacteria were divided into 7 main phylum:Actinomycetes,Proteobacteria,Acidobacteria,Bacteroidetes,Pseudomonas,Aeruginosa,Blastomonas,and Verrucosa.After analyzing the bacteria diversity of all kinds of samples,it is found that there are certain differences between different samples due to the influence of environmental characteristics,geographical location and other factors.The isolated bacteria were planted on a plate spread with Staphylococcus aureus and Acinetobacter baumannii.After screening,20 strains with antibacterial effect were finally screened,mainly distributed in Microbacterium of Actinobacteria,Pseudomonas of Proteobacteria and Bacillus of Firmicutes.The draft genomes of strains F01002 and 3H14 with obvious antibacterial effects were sequenced,and the active substances were analyzed by antiSMASH and KEGG website.Finally,we identified three potential novel strains.We named strain E01020T as Pedobacter greatwallensis,strain L53T as Hanstruepera crassostreae and strain B3227T as Halakalibacillus sediminis.The research significance of this paper lies in broadening the research scope of microbial diversity in polar regions,obtaining abundant resources of polar bacteria,and analyzing its potential research value,so as to provide abundant research materials for further exploring the functions of polar microorganisms.In the case of few studies on the antibacterial activity of bacteria in polar soil,strains with good antimicrobial activity were screened from the polar soil in this study,providing strain resources for further extraction of novel antibacterial substances. |
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