Analysis Of The Bacteria And Archaea Diversity Of Saline-alkaline Soil Of Four Sites In Xinjiang

For their special natural environment,Xinjiang has become my country's soil salinization area with a wide distribution area,many types,and the heaviest salinity.At the same time,it has also nurtured special and diverse microbial resources.In order to understand the microbial diversity of the saline-alkali soil near the oasis area in Xinjiang,and to provide a material basis and scientific basis for using microorganisms to improve the saline-alkali soil,this study took soil samples from four typical saline-alkali soil distribution areas across the southwest to northeast of Xinjiang as the object,the soil physicochemical properties collected from the saline-alkali land in Tashkurgan County,Wensu Salt Mountain,the desert in Fukang in the southern margin of the Gurbantunggut Desert and in Qinghe County bordering Mongolia were detected by conventional soil physicochemical property testing methods,Isolation and identification of culturable bacteria in the saline-alkali soil of four places using conventional microbial isolation and culture techniques,Detection of bacterial and archaeal diversity in soil from four regions by high-throughput sequencing technology,The main results are as follows:(1)The soil p H of the four places was above 7.8,which was alkaline.The soil salt content is above 40 mg/g,the soil anions are mainly SO₄^2-,Cl^-,Cl^-/SO₄^2-and SO₄^2-,and the cations are mainly Na⁺.According to the classification standard of saline-alkali soils,Taxian and Qinghe soils belong to sulfate type,Wensu soil belongs to chloride type,and Fukang soil belongs to sulfate-chloride type.(2)A total of 258 strains of pure cultured were isolated from the saline-alkali soil samples of four places by traditional methods,of which 67,67,62 and 62 strains were isolated from Taxian,Wensu,Fukang and Qinghe samples,respectively.According to the 16S r RNA gene sequence,it belongs to 40 genera of Firmicutes(129 strains),Actinobacteria(129strains),Proteobacteria(69strains),Deinococcus-Thermus(54 strains)and Bacteroidetes(1 strain).Among them,the isolates from the Taxian sample are distributed in 4 phyla and 16 genera,the isolates from the Wensu sample are distributed in 4 phyla and 13 genera,the isolates from the Fukang sample are distributed in 3 phyla and 17 genera,and the isolates from the Qinghe sample are distributed in 3 phyla and 17 genera.Bacillus was the dominant genus in the isolates from Taxian,Fukang and Qinghe samples,and Microbacterium was the dominant genus in Wensu samples.The specificity analysis showed that the bacteria shared by the four samples was Bacillus,There are 9 endemic genera in Taxian(15 isolates,22.38%),3 endemic genera in Wensu(9 isolates,13.42%),6 endemic genera in Fukang(9 isolates,14.51%),and 7 endemic genera in Qinghe(15 isolates,24.19%).The results showed that the saline-alkali soils of the four regions were rich in cultivable microbial diversity,with significant regional differences in microbial taxa,and contained a large number of microbial resources that had not yet been tapped.(3)A total of 12 samples of saline-alkali soil from four regions were sequenced and sorted through high-throughput to obtain 609,219 valid sequences,accounting for 81%of the total sequencing volume.The bacterial taxa represented by the valid sequences were distributed in 43phyla and 915 genera.The soil taxa of Taxian,Wensu,Fukang and Qinghe belonged to 28 phyla with 453 genera,30 phylum with 532 genera,37 phylum with 554 genera and 32 phylum with562 genera respectively.There are 23 bacterial phyla shared by the four regions,and 4,5 and 1unique bacterial phylum in Wensu,Fukang and Qinghe,respectively.There were 203 bacterial genera shared across the four regions,with 8,184,62 and 78 endemic genera,accounting for1.7%,34.6%,11.2%and 13.9%of the total number of genera.Bacteroidetes,Actinobacteria and Proteobacteria were the dominant phyla in the saline-alkali soil of the four regions.The dominant bacterial genus in the saline-alkali soils of Taxian,Fukang and Qinghe were all norank?f?Nitriliruptoraceae,but the proportions were different.The dominant bacterial genus in Wensu saline-alkali soil was Salinibacter.In the saline-alkali soils of the four regions,bacterial diversity was less than 1%in abundance at the genus level the relative proportion of the samples in Fukang and Qinghe was higher than that in Taxian and Wensu,indicating the microbial diversity of the two places richer.Compared with the results of the culturable method,the bacterial community structure and diversity in the saline-alkali soil obtained by high-throughput technology were significantly different.(4)The correlation analysis between the diversity of uncultured bacterial taxa and environmental factors showed that the bacterial community composition was related to soil Cl^-,SO₄^2-,HCO₃^-and Ca²⁺concentrations,and the dominant bacteria genus Salinibacter in Wensu samples showed significant correlation with soil Cl^-ions Positive correlation,the dominant bacteria genera norank?f?Nitriliruptoraceae,Antarcticibacterium,Gillisia and Halomonas in Taxian and Fukang samples were positively correlated with SO₄^2-and HCO₃^-,bacterial community composition of Qinghe samples It is positively correlated with CO₃^2-.The results showed that soil Cl^-,SO₄^2-,HCO₃^-and Ca²⁺contents were the main factors affecting the dominant bacterial groups.(5)The high-throughput analysis of archaeal 16S r RNA gene sequences of samples from four places showed that the archaea were distributed in 68 genera in 4 phyla,with Halobacteria in the phylum Euryarchaeota and Nitrososphaeria in the phylum Thaumarchaeota as the dominant flora.The dominant genera in Taxian,Wensu,Fukang and Qinghe samples were norank?f?Halococcaceae,Natronomonas,norank?f?Halococcaceaeand Candidatus?Nitrocosmicus,respectively.The composition of archaeal community in Qinghe soil is obviously different from that of the other three places.The correlation analysis with environmental factors showed that the structure of archaea in saline-alkali soil was mainly affected by the types of anions and cations(Cl^-,SO₄^2-,HCO₃^-,Ca²⁺)and total salt content.The research of this project has fully demonstrated the diversity of culturable and uncultivated bacteria in the saline-alkali soils in the four regions of Xinjiang,enriched the microbial resource pool,and revealed the changing rules of bacterial and archaeal community structures in the saline-alkali soils along the line from southwest to northeast.Revealing that the changes of its taxa are mainly affected by soil physicochemical factors,especially the diversity of anions and cations.The research provides resource materials for using microorganisms to improve saline-alkali soil,and has important theoretical and practical value.