Studies On The Physioligical Characteristics And 16S RRNA Genic Diversity Of Bacteria In Glacier

In this study, by cultivation-independent and PCR amplification methods, the physiological characteristics and csp (cold-adapted) gene clone of bacteria from Muztag Ata ice cores of the Tibetan Plateau were investigated; the bacterial diversity and abundance in the snow of glacier No.51 in Kuytun were examined through 16S rRNA gene clone library and flow cytometry approaches. The conclusion we get are as follows:1. Physiological characteristics and properties of cold-adapted glacial microorganisms which are exposed to constantly extreme environmental conditions were studied. We observed the effects of temperature and pH on the growth of 5 isolates from the Muztag Ata glacier, and according to conservative amino acid sequence of cold-induced protein, we designed a pair of primers cloning cold-induced gene csp and carried out PCR amplifications. This investigation suggested there were three types of microorganisms: the suitable temperature for psychrophilic bacterial growth was 0℃-23℃, and the optimum is 15℃; the suitable temperature for psychrotrophic growth was 0℃-40℃, and the optimum 23℃; the suitable temperature for widely thermophilic bacterial growth was 0℃-45℃, the optimum 30℃. The different response to pH changes of the Muztag Ata ice cores isolates indicated pH was an important factor influencing the bacterial quantitative distribution on the glacier surface . We have successfully colonized csp gene fragment from Staphylococcus equorum Muzt-D84 and the size was 171bp.2. The ratio of live to dead cells is 1:5 to 2:3 and the total cell counts in selected 13 samples from glacier No.51 in Kuytun fluctuated from 3.70×10⁴ cell·ml^-1 to 69.50×10⁴ cell.ml^-1cell·ml^-1 by flow cytometry, this suggested microorganisms from different climatic environment were blown here and deposited on the surface of glaciers at specific historical times, and the distribution of microorganisms reflected the climatic environment of different times and only 20% of these Microorganisms from glacier No.51 in Kuytun were alive.3. The bacteria were recovered by clone library establishment of the 16S rDNA molecules from the melt water samples of glacier No.51 in Kuytun and 88 clones were sequenced. Based on their 16S rRNA gene sequences, the sequences were divided into 8 groups: Proteobacteria, Actinobacteria, Cyanobacteria, Cytophaga-Flavobactreium- Bacteroides(CFB), Deinococcus-Thermus, Chloroflexi, Firmicutes and Eukaryotic chloroplast. The dominant group was Proteobacteria ac-counting for 57% of the total clones. Clones that fell into the groups CFB, Cyanobacteria, Actinobacteria and other groups accounted for 23.7%, 7%, 2.48%, 3.55%. These recovered sequences were beleonged to the genera Deinococcus, Variovorax, Microcoleus, Polyangium, Phormidium, Bradyrhizobium, Thiobacillus, Polaromonas, Sphingomonas, Hymenobacter, Arthrobacter, Leifsonia, Janthinobacterium, Halobacillus, Hymenobacter, Pedobacter, Panaciterramonas, Leptolyngbya, Limnothrix, Flectobacillus, Flavobacterium, and some other eubacteria. All the sequences were affiliated with 31 genera, 9 sequences could not classified into the genus level, while the genera Panaciterramonas and Variovorax were dominant on the genus level. The bacterial community structure showed evident altitudinal distribution characteristics: the microbial abundance of high altitude was less than low altitude, and some specific species were distributed in different ice or snow environment.