Biodiversity Of Bacterial Communities On The Rock Surfaces And The Rock-Weathering By The Culrural Bacteria From The Debris Flow Source Area In Dongchuan (China)

The rock located in the debris flow area in dongchuan is slate.Slate is a shallow metamorphic rock with a plate shape structure.Slate weathering can damage rock mass structure and lead to the outbreak of debris flow.The samples of debris source flow and circulation areas were collected from Dongchuan in Kunming,Yunnan Province.The bacterial communities of the samples were characterized by using Illumina Miseq high-throughput sequencing technology and the relationship between the community structure and the sample factors were also analyzed.In addition,rock-weathering bacteria were isolated from the above samples and characterized for their rock-weathering ability and populations.This study will reveal the bacterial communities of the samples and the key factors affecting them.This study will also enrich the resource of the rock-weathering bacteria and provide the experimental basis for the interaction between the rocks and bacteria.Miseq Illumina high throughput sequencing analysis showed that the OTU number of bacterial communities were as followed:source area sample E2(585)>circulating area sample F(227)>source area sample E3(232)>source area sample D2(158).Sample E2 had the higest and sample D2 had the lowest diversity of the bacterial community.The community diversity of the samples F and E3 was lower than sample E2 but higher than sample D2.Phylogenetic analysis showed that Firmicutes(68.90%),Proteobacteria(12.67%)and Actinobacteria(11.08%)were the dominant bacterial communities in the samples.The samples D2,E2,E3,and F had 11,23,12,and 11 dominant genera,respectively.The four samples had eight common dominant genera including Lactococcus,Bacillus,Arthrobacter,Pseudomonas,Carnobacterium,Lysinibacillus,Solibacillus and Streptococcus.The proportion of Actinobacteria and Proteobacteria were significantly negatively correlated with Ca and Fe contents,while the proportion of Firmicutes was significantly positively correlated with Fe and Ca contents but negatively correlated with pH.A total of 302 bacterial strains were isolated from the above samples.Rock weathering experiment showed that 68.5%of the strains had the ability to release Fe,Si,Al and Ca from the rock.Based on Ca release of the strains,the strains were divided into three groups including high(>800 ?M),the moderate(400-800 ?M),and low(<400 ?M)rock weathering ability.In total 302 strains,78.8%,19.5%,and 1.7%of them belonged to high,moderate,and low effective rock weathering bacteria.The samples D2,E2,E3,and F had 60.5%,80%,90.7%,and 88.3%of high effective weathering ability respectively.Phylogenetic analysis revealed that the rock-weathering strains belonged to Actinobacteria(60.9%),Proteobacteria(16.2%)and Firmicutes(22.9%)and 13 taxonomic genus including Arthrobacter,Pseudomonas,Ensifer,Bacillus,Acinetobacter,Rhizobium,Terrabacter,Pantoea,Enterobacter,Sphingomonas,Staphylococcus,Microbacterium,Micrococcus.The common genera were Arthrobacter and Bacillus in the samples.Micrococcus was specific to sample D2,Pantoea?Enterobacter?Staphylococcus and Microbacterium were specific to sample E2,while Rhizobium?Terrabacter?Acinetobacter and Ensifer were specific to sample F.