Community Structure And Diversity Of Bacteria In Biological Soil Crusts Of Hunshandake Deserts

Biological soil crusts is the main component of arid and semiarid areas and has great significance to desert ecosystem’s stability, restoration and reconstruction. Microorganism is the major components of BSCs and its diversity and community structure is the basis on understanding of microbe drivers for BSCs’formation and development. However, bacteria in BSCs, especially functional bacteria’s diversity and community structure is little known and need some related research to reveal the basis of the relationship between the bacteria and BSCs.This research sampled three kinds of BSCs(algal crust, lichen crust and moss crust) and their conresponding subsoils in Hunshandake desert (near Duolun Guniang Lake). Using the high-throughput tenique of Miseq, the community structure and diversity of bacterial, anoxygenic phototrophic bacteria (APB) and nitrogen-fixing bacteria in three different types of BSCs and also how they were related with soil’s properties were analyzed. At the same time, the metabolic function of BSCs were studied by ECO. The follows are the results.1) Physical and chemical properties of soil. The algae, lichen and moss crust, the water content(WC), organic matter(OM), available nitrogen(AN) and available phosphorus’s (AP) content of the BSCs’upper layer is higher than the subsoil, but the pH is opposite.2) Soil metabolism. The BSCs’upper layer has higher carbon source utilization efficiency than the subsoil, during the date of AWCD. On the overall trend, every sample has the simlar low carbon source utilization, in the adaptive phase of 0 to 24 hours; at 24 to 108 hours, every sample’s carbon source utilization grow fast, and tend to smooth at 108 to 156 hours; after 156 hours, start to reduce, all of the samples can’t use the 2-Hydroxy Benzoic Acid.3) Diversity analysis. The bacteria’s shannon index indicates that the diversity of subsoil was higher than that of BSCs, for example the Shannon index of algae crust and its subsoil are 5.09 and 5.66; the algae and moss crusts’ diversity of pu/M was richer than that of the subsoil, the lichen crusts are not; nif H diversity showed moss crusts’was higher than lichen crusts, and the algae crusts was the least.4) Microbiological Community. There were ten bacterial phylum, namely Cyanobacteria (0.37%-29.22%), Actinobacteria (22.12%-50.83%), Proteobacteria (16.63%-27.82%), Chloroflexi (3.92%-13.81%), Acidobacteria (6.29%-16.43%), Bacteroidetes (1.56%-5.45%). The phylum of Cyanobacteria, Proteobacteria, Bacteroidetes were richer in upper layer, while Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes were richer in subsoil layer; APB belonged to Proteobacteria (58.46%-94.43%), Chloroflexi (0.02%-1.80%), environmental-samples-norank (5.55%-41.10%). Besides the Cyanobacteria and Proteobacteria, the most of nitrogen-fixing bacteria failed to be classified into known phylum.On genus, the bacteria were divided into 40 different genara, such as Microcoleus, Microvirga, Marmoricola, Actinoplanes, Blastocatella, Micromonosporaceae, Pseudonocardia and etc.; APB belonged to 7 different genus, namely Bradyrhizobium, Brevundimonas, Methylobacterium, Rhodospirillum, Roseiflexus, Sphingomonas, Unclassified-Gammaproteobacteria-(miscellaneous)-norank. The nitrogen-fixing bacteria failed into Bradyrhizobium, Alicycliphilus, Nostoc and Cyanothece.5) The relationship between microbial community and environmental factors. The OM, AN and WC had the similar influence on lichen crusts layer and BSCs’ subsoil in bacterica community; the AP and AN had the similar influence on BSCs’ crust layer.In conclusion, bacteria, APB and nitrogen-fixing bacteria in BSCs had high diversity. Oxygenic photosynthetic bacteria, APB and nitrogen-fixing bacteria maybe play a major role in BSCs’ formation and development. This paper provides the evidence that the functional communities has influenced on the BSCs’ formation and development, establish the foundation to utilize the BSCs’ species resources and make artificial BSCs, and has important theoretical value and practical significance.