Diversity And Functional Enzyme Screening Of Cultured Halophilic Archaeon In Lop Nur Region

To better resolve the scientific problem of cultured Halophilic archaeon in Lop nur region, this thesis took the Halophilic archaeon in Lop nur region to be the research object. The present study mainly focus on the diversity and functional enzymes screening of the Halophilic archaeon isolated using cultural dependent methods from the samples collected from Lop Nur region On the basis of the experience of isolating actinomycetes in salt environment, suitable media were selected for the related isolation experiments. The diversity of halophilic archaeon was studied mainly based on culturable techniques and phylogenetic analysis based on 16S rRNA gene sequences. In addition, our experimental results indicates that Halophilic archaeon has much potential application values by screening three functional enzymes. All of these will provide technical support and theorical basis for further research on the resource of Haliphilic archaeon.Four media namely CCMS, modified Gause 1, ISP5, HV agar were used to isolate the Halophilic archaeon from 13 samples in Lop Nur region. After dereplicating, similar strains based on their colony characteristics,16S rRNA gene of 56 strains were sequenced for further study. BLAST analysis of the almost complete 16S rRNA gene sequences indicate that these strains belonged to 5 new potential genera(Group 1,Group 2,Group 3,Group 4,Group 5) and 10 described genera( Halopelagius, Natrinema, Haloterrigena, Halalkalicoccus, Halopiger, Halodaptatus, Halorubrum, Natronococcus, Halosarcina, Halogenomonos). They can be further classified into 5 new potential genera and 38 new species taxa. Above results indicate there is a rich resources of Halophilic archaeon in Lup Nur region. The Shannon index was 1.795, which is not very high, indicating that there is a huge gap for research on the Halophilic archaeon in Lop Nur region. Diversity and distribution of Halophilic archaeon were studied based on strains isolated from these samples. The isolation results revealed that the CCMS medium is a good isolation medium for Halophilic archaeon compared to modified Gause 1 medium while ISP5 and HV agar showed little or no isolation effect.17 strains were further selected to determine their salt tolerance level and enzymatic activities. The range of salt concentration tolerance of most strains was 10%-35% (optimum at 20%). 70.6% of the strains showed positive result for amylase activity, 35.3% for protease and 82.4% for esterase activity. These results further revealed the high salt concentration tolerance of these strains validate the feasibility of isolating Halophilic archaeon from low salt environment. On the other hand, the high enzymatic activities provide theorical support for further research on the Halophilic archaeon with potential for industrial application.Some new strains were further investigated using polyphasic taxonomic approach. On the basis of the phylogenetic analysis and phenotypic distinctiveness, strains YIM 93701,YIM 93664 were classified as new species of the genus Halalkalicoccus.In conclusion, many new taxa of Halophilic archaeon were isolated by using modified isolation media. Through screening functional enzymes, the results indicated Halophilic archaeon had potential application value in industry. The results presented above showed that there is a rich Halophilic archaeon diversity for further exploitation.