Diversity And Low-temperature Adaptation Of Culturable Bacterial In Snowpack From Different Glaciers On The Tibetan Plateau & Its Adjacent Regions

Glacier is the special complex ecosystem.It should be considered as a stabilizing factor for sustaining for organism and biological macromolecular due to its property of low temperature and scant nutrition. There circumstance provide us "live fossil" on evolution of life and environment on earth. Mircoorganism originating from various atmospheric aerosol and dust entered the glacial ecosystem with atmospheric circulation through dry/wet deposition,then the glacier, therefore, becomes the nature huge repositories of viable microorganisms. The study on microbial ecology of glacier has important implication on the reconstruction of paleoclimate and paleoenvironment; lead to the establishment of bio-indication of gradual and rapid climate change, and other physical phenomena; the research of the evolution of life and biological clock; search for biotechnologically potential cells and their metabolic end-products.This study presents comparative culturable bacterial diversity and low-temperature adaptation (temperature, salinity, pH, and extracellular hydrolytic enzyme activity) in the the seven snowpack which were collected from glaciers along the north-south transect of the Tibetan Plateau and is adjacent regions, using culture-dependent combined with culture-independent techniques (identified by 16S rRNA genes). The following major conclutions were obtained:I. Culturable bacteria diversity in the snowpack varied at different glaciersBacteria was recovered by using oligotrophic medium at low-temperature, Isolates were analyzed by amplified rDNA restriction analysis (ARDRA) and based on 16S rRNA gene sequencing resulting in 82 different groups.These strains belonged to Actinobacteria, Firmicutes, Bacteroidete、α-,β-,γ-Proteobacteria of 26 genera(Arthrobacter、Mycetocola、 Pseudomonas、Sphingomonas、Janthinobacterium、Brevundimonas、Polaromonas、 Flavobacterium、Bacillus、Caryophanon、Planococcus、Staphylococcus、Devosia、Clavibacter、 Streptomyces、Subtercola、Paracoccus、Acinetobacter; Stenotrophomonas、Cryobacterium、 Psychrobacter、Leifsonia、Salinibacterium、Microbacterium、Frondihabitans、Chryseobacterium). Bacterial source analysis show that:First, the dominant bacterial group is different; Second, The culturable bacterial genera are different that showed the universality and particularity, such as the Arthrobacter sp. in seven snowpack has a distribution, and Frondihabitans sp., Leifsonia sp., Cryobacterium sp., etc. only exist in one snowpack; Finally, the bacterial diversity in the snowpack at different glaciers was related to the surrounding environments.II. Physiological and biochemical characteristics of culturable bacterial at low-temperatureRepresentatives culturable bacterial of the 82 groups were deceted the physiological and biochemical characteristics including temperature, salinity range (adding NaCl) and pH range. Get the following results:1), Most isolates were psychrototerant, varied in their growth temperature range (4～37℃),and individual characteristics of bacteria strains were mesophilic; 2), All the stains could grow without NaCI in the medium and the tolerance to NaCI varied from 0 to 8% and showed the growth of their respective characteristics. Overall, all the strains are tolerated in the salinity tolerance of the characteristics of the salt; 3), Strains could grow in the pH range of 3-13,48% strains could grow above pH 5, in general, all the strains showed more is the growth of an alkaline trend; 4), Of all 67 strains of culturable bacterial strain isolated from extracellular hydrolytic enzymes at 20℃ (in the case of amylase, lipase and cellulase), approximately 85%,30% and 19% of the strains possessed lipase, amylase and cellulase, respectively. More than half of the isolates were pigmented. In addition to the strains of Tianshan No.1 Glacier are majority gram negative bacteria (α-,β-,γ-Proteobacteria), other glaciers are accounts for high proportion of gram positive bacteria (Actinobacteria, Firmicutes and Bacteroidete), especially high G+C (HGC) Actinobacteria has an absolute advantage in Muztag Ata, Guoqu and Demula Glacier. Results show that the survival of microorganisms under different temperature conditions has its physiological mechanism adapt to the environment, and also explains the low temperature microorganisms in the environment is the result of natural selection and adaptation.In conclusion, there are existed differences in culturable bacterial diversity on the Tibetan Plateau & its adjacent regions,this observations were mainly due to the difference of local climate and atmospheric circulation privailled in different spatial glaciers.the strain under low temperature conditions of physiological adaptability illustrates microorganism selection and the ability to adapt to the cold environment, and this ability could provides information help hunman to get potential new energy.