Study On Microbial Diversity Of Surface Sediments From Salt Lake In Badain Jaran Desert

Badain Jaran desert,the third largest desert in China,has numerous lakes and rich microbial resources.Combining with Mothur,Canoco,and R software,the study will use Illumina Miseq high-throughput sequencing to study the community structure and diversity of bacterial and archaeal in badain jaran desert saline lake sediments.Quantitative PCR was used to determine the abundance of sulfate-reducing bacteria in sediments.Furthermore,this thesis presents a preliminary understanding of the microbiological characteristics of sediments in Saline and Algae lakes.It also improves the development of microbial resources in the saline-alkali soil environment.And the main findings are as follows:?1?With referring to the soil classification criteria,measuring the physicochemical properties of Saline-alkaline sediments in Badain Jaran Desert shows that the sediments from Badan Lake-East and Baoji Tolgoi are low-salinity sediments;Shuanghaizi-West and Shuanghaizi-east are high-salinity sediments;Badain Lake-West,Yindeletu,Qinghaizi.Nanhaizi,Miaohaizi and Norrtu are ultrahigh-salinity sediments.With referring to the chemical classification standards for water,determining the physicochemical properties of the saline-alkaline lakes in the Badain Jaran Desert shows that Badan Lake-East and Baoji Tolgoi are sodium brackish water lakes;Shuanghaizi-West and Shuanghaizi-East are sodium-chloride salt lakes;Bataan Lake-West and Indertel diagrams.Qinghaizi,Nanhaizi,Miaohaizi,and Norrtu are sodium carbonate salt lakes.?2?There are 58 types of bacteria in the sediments of Saline and Alkaline Lake in which Proteobacteria and Firmicutes are two main types.The most dominant species in ultrahigh salinity sediment and high salinity sediment is Firmicutes,accounting for 37.1%-61.6%.The most dominant species in low-salinity sediment is Proteobacteria which accounts for about 50%.There are 15 types of archaea in which Euryarchaeota is accounted the main category with a proportion of 32%-99%.?3?In the low-salinity sediment,the genus of low-salinity soil bacteria are Thiobacillus,and the dominant bacteria of the archaea are Methanobacterium.In the sediment with high salinity and ultrahigh salinity,the dominant bacteria are norank_Syntrophomonadaceae,and the dominating bacteria in the archaea are Halovivax.?4?In low-salinity sediment,the bacterial diversity was positively correlated with NH₄⁺and negatively correlated with pH,Sal,SO₄^2-,and Cl^-.In high and ultrahigh salinity sediment,the bacterial diversity was positively correlated with pH,Sal,SO₄^2-,and Cl^-and negatively correlated with NH₄⁺.The study presented no obvious correlation between the diversity of archaea and salinity.Archaea diversity can be influenced by various factors.?5?Realtime fluorescent quantitative PCR showed that the gene abundance of sulfate-reducing bacteria was 1.24×105copies/g-6.26×106copies/g.And the correlation analysis indicated that the sulphate reducing bacteria gene abundance was positively correlated with NO₃^-.What is more,the sulphate reducing bacteria gene abundance was significantly negatively correlated with water content and total phosphorus.