Study On The Cyanobacterial Diversity In Gurbantunggut Desert,Northwestern China

The Gurbantunggut Desert is the largest fixed and semi-fixed desert in China,and biological crust plays an important role in desert fixation.The biological crust contains microorganisms such as bacteria,fungi,cyanobacteria and green algae.The algae crust formed mainly by cyanobacteria is a sign that the dunes begin to be fixed.Cyanobacteria can carry out photosynthesis carbon fixation,and some cyanobacteria can fix nitrogen.This process will increase the soil organic matter content and improve the soil to some extent.Therefore,the study on the non-culture and cultivable diversity of cyanobacteria in the algae crust of the Gurbantunggut Desert has certain theoretical significance for us to grasp the relationship between cyanobacterial diversity and environmental factors in the Gurbantunggut Desert,and for future prevention.And the governance of desertification has practical significance.In this paper,the cyanobacteria non-cultivation and cultivable research were carried out on 10 plots in the Gurbantunggut Desert.The cyanobacteria 16Sr RNA and psb A gene clone libraries were constructed respectively.The diversity composition of cyanobacteria was obtained by biological informatics analysis,and the effects of soil physical and chemical properties on the diversity of cyanobacteria were analyzed.The cyanobacterial diversity of cultured cyanobacteria was identified by culture observation.Through research,the following conclusions are drawn:?1?16S rRNA clone library alignment results The Gurbantunggut desert cyanobacteria were divided into the following categories:1)Microcoleus,accounting for 45.66%;2)Phormidium,accounting for 9.25%;3)Oscillatoria,accounting for15.61%;4)Chroococcidiopsis,accounting for 7.51%;5)Nostoc,accounting for3.47%;6)Leptolyngbya,accounting for 0.58%,7)Scytonema,accounting for 1.16%,8)Synechococcus,accounting for 1.16%.Unclassified cyanobacteria accounted for15.61%of all sequences.The genus Microcoleus is a dominant genus in the cyanobacteria community.The results of psbA gene clone library were as follows:1)Geitlerinema,accounting for 50%;2)Microcoleus accounted for 4.84%;3)Nostoc accounted for 3.23%;4)Anabaena accounted for 41.94%.The 16S rRNA sequences were used for classification.The non-cultured cyanobacteria in the Gurbantunggut Desert were divided into 5 families and 8 genera.The psb A gene is a functional gene related to chlorophyll chloroplast photosynthesis,and can also be used as a cyanobacteria diversity research object.The classification of this species is less than that of 16S rRNA sequences.The psbA gene sequence is used for classification.The non-cultivated cyanobacteria in the Gurbantunggut Desert are divided into 2 families4 genera.?2?According to the NMDS analysis,there were significant differences among the 10 samples,indicating that there were differences in the species of cyanobacteria in each sample.The first two axes of the PCA analysis explained a total of 63.62%,and the first principal component occupied the vast majority of the interpretation.According to the similarity and difference of the sample,the first principal component was the soil total nitrogen content.The effect of all environmental factors on the OTU abundance was calculated as NO₃^--N>TK>pH>MBC>SOC>MBN>TN>NH₄⁺-N>TP.Soil organic matter,ammonium nitrogen,nitrate nitrogen and total phosphorus were positively correlated with the diversity of cyanobacteria community,and the correlation was NO₃^--N>TP>NH₄⁺-N>SOC.Ammonium nitrogen,nitrate nitrogen and soil organic matter have a great influence on the richness and diversity of cyanobacteria communities in the Gurbantunggut Desert,especially nitrate nitrogen,which is significantly positively correlated in various cyanobacteria..?3?In the 16S diversity analysis of non-cultured cyanobacteria,the richness of cyanobacterial community was characterized by southern desert>eastern desert>northern desert>western desert;The order of diversity of cyanobacteria in different landforms is:dune lowland>leeward slope>windward slope>sand dune top.?4?Among the 10 soil samples observed in the culture,there were 29 species of algae belonging to 3 phylum,10 families and 13 genera,including 19 species of cyanobacteria,4 families,9 genera,accounting for 65.5%of the total species,advantages in round or oval.Among them,the dominant species of cyanobacteria are the genus Chroococ and the genus Oscillatoriaceae,and the dominant species are the genus Chroococcus and the genus Oscillatoria.The dominant species of algae in the10 soils from which we extracted the samples were Synechococcus distomicola and Microcolus vaginatus,distributed in all areas of algae crusts in the Gurbantunggut Desert.