Study On Microbial Diversity Of Two Thermal Hotspring Areas In South Of Tibetan And Screening Object Strains Of Producing Cellulase And Chitinase

As the Tibetan region is located in the Mediterranean-Himalayan tropical,while the Asia-Europe plate and the Indian Ocean plate squeeze each other,which has a wealth of geothermal resources.In the whole territory of Tibet,the number of hot springs are more than 700 and widely distributed,but mainly concentrated in the southern region of the Tibet.So in the present study,Daggyai and the Quchomo two thermal hot spring areas were selected for the research of microbial diversity.First,high-throughput sequencing technique was carried out for ten samples of two geothermal sites,and the microbial diversity was analyzed by combining with the geochemical parameters and geographical factor of hot springs.The results showed that the microbial community structure of the hot spring environment in Tibet was significantly different from that of other habitat environments.The dominant members of Bacteria were Chloroflexi and Aquificae,while Parvarchaeota and Crenarchaeota were the dominant in Archaea.The microbial diversity is very abundant and there are a variety of unknown microbial groups;the temperature was of the limiting factor,with other environmental factors together determine the microbial community structure.Combined with the analysis of geophysical parameters show that the temperature has big contribution for the the structure of the microbial community.In geochemical parameters,Li+,SO42-,Br-,Cl-,NH4+,K+,F-and Al,Be,Zn,Cu,Ge,Sr,Bi and U etc.trace elements together affected the microbial community structure.It can be seen that various environmental factors of hot springs have created a complex microbial community structure.Secondly,ten samples,for the routine laboratory culture method,were selected,which based on at a wide range of temperatures and near neutral pH in order to evaluate the temperature's influence on microbal diversity.The results showed that the diversity of the isolates was changing regularly by the difference in temperature of the samples,that is,the temperature was positively correlated with the diversity of the samples.Totally,382 isolates were obtained and these isolates were distributed in 6 families,7 classes,9 orders,12 families,24 genera and 56 species.The effect of Biolog ECO microplate method on microbial isolation was discussed.Two samples,namely TGJ 3 and QZM 6,were selected for the diversity of the isolates.The results showed that the method had a certain effect on the microbial resource excavation compared with the traditional isolation method.At the same time,two new species YIM 75003T and YIM 75004T of the genus Altererythrobacter were identified by polyphasic taxonomy approach and identified as Altererythrobacter lauratis sp.nov.and Altererythrobacter palmitatis sp.nov.Finally,the 86 representative strains were selected for screening and determing the chitinase and cellulase activities.Among them,the positive rate for these strains was 41.9%and 30.2%,respectively.At the same time,three strains with higher chitinase activity and one strain with higher cellulase activity were found.