Microbial Diversity In The Qinghai-Tibet Plateau Permafrost Region And Its Potential Applications

The permafrost environment represents 26% of terrestrial soil ecosystems, is considered extreme because indigenous microorganisms must survive prolonged exposure to subzero temperatures and background radiation for geological time scales in a habitat with seriously lack of liquid water reachable nutrition. In the last century 90's, with the purpose to study the life characteristic and evolution under the low temperature environment, as model to research extraterrestrial life and to exploration of the microorganism resources under the low temperature environment, research of permafrost microbiology obtained it's vigorously support and considerable achievements. The Qinghai-Tibet Plateau represents a unique and important permafrost environment. However, its microbiology remains nearly unexplored to date. In addition, the permafrost degradation is very severe in the Qinghai-Tibet Plateau under global warming scene. Thus, there is an urgent need of investigations concerning microorganisms in this extreme and unique soil.In this study, samples were collected from Beilu river basin, the hinterland of Qinghai-Tibet Plateau. And the investigations were concentrated in the characteristics, distribution and diversity of the viable microorganisms from the Qinghai-Tibet Plateau permafrost region including with the study concerning the description of novel bacteria species and the study of some candidate strains that they might be of potential value for biotechnological exploitation. The results obtained here were summarized as follows:1. The numbers of colony forming unit (CFU) were ranged between 0 and 10~7/g dry soil. Phylogenetic analyses indicated that all the isolates belong to 19 genera and fell into six categories: high G+C Gram-positive bacteria, low G+C Gram-positive bacteria,α-proteobacteria,β-proteobacteria,γ-proteobacteria and CFB group bacteria. These results of characterization suggested that the isolated population is psychrotolerant but owns very less psychrophiles.2. The viable bacteria on PYGV agar modified by adding sodium bicarbonate were varied between 10~2 and 10~5 CFU/g of dry soil. Forty-eight strains were gained from 18 samples. Through phylogenetic analyses, these isolates fell into three categories and six genera. The strains could grow best at pH values ranging from 9 to 9.5 with the optima temperatures ranging from 10℃to 15℃. These results indicate that there are populations of nonhalophilic alkaliphilic psychrotolerant bacteria within the permafrost of the Qinhai-Tibet plateau. The abilities of some strains to produce cold active extracellular protease suggest that they might be of potential value for biotechnological exploitation.3. The comparisons of the utilized isolation procedures suggest that, though the same batch of samples used, the different media resulted in the different isolated populations and the same medium with different pH or different incubation temperatures could isolate very different bacteria populations. Combined with the results of cultivating some functional kinds of bacteria and actinomyces, the important significances of using multiple strategies to investigate and explore microorganism resource were analysed.4. A part of strains can produce cold active extracellular hydrolytic enzymes. The result showed that a Brevundimonas strain, isolated from a permafrost layer sample with the depth of 570cm, had relatively stronger ability to produce cold active extracellular amylase and cellulose. Subsequently, the further researches were focus on the optimal conditions to produce the enzymes for biotechnological exploitation of the permafrost organisms.5. With using the routine methods and phylogenetic analyses, results indicate that a good part of strains isolated from the Qinghai-Tibet Plateau permafrost region might potentially be new taxa. Subsequently, investigation work concerning description a CFB group bacteria strain as a novel species was completed and the scientific name Hymenobacter psychrotolerans was proposed. In addition, some candidate strains might potentially be new taxa was still under recent study.The results above indicate that the unique permafrost on the Qinghai-Tibet Plateau accommodates a very special original microbial assemblage. There are many novel taxa of microorganisms need to be investigated and a great potential value of microbial resources ready to be explored.