Diversity And Community Structure Of Soil Bacteria And Distribution And Function Of QS Bacteria Of Root Envitonment In Beidaihe Coastal Wetland

Coastal wetlands with unique ecological and resource potential,were a complex ecosystem.In recent years,the wetland degradation became gradually significant ecological problems,which attract the attention from all over the world.In this study,Beidaihe coastal wetland was in a state of degradation period.Under the request of relevant departments,we performed the vegetation restoration work in degradation area.Three aspects were studied concerning the relationship between vegetation and bacteria in the study.1)The influence of coastal wetland of vegetation degradation on soil microbe diversity and community structure.2)The succession law of soil microbe during vegetation restoration in degraded area.3)The diversity and function of quorum sensing(QS)bacteria in the root environment.In coastal wetlands,the degradation of vegetation decreased the soil microbial diversity,and changed the community structure.In phylum,the abundance of Proteobacteria and Firmicutes in the degraded areas was significantly higher than that in the vegetation area,while the abundance of Planctomycetes was significantly lower than that in the vegetation area.At class level,the abundance of gamma-proteobacteria and bacilli was significant increased,and phycisphaerae and acidimicrobiia significantly decreased in degradation areas.Combined with environmental factors,high salt and PAHs contents in the soil could reduce the abundance of microbe.The co-occurrence analysis found that the ecological function of autotrophic microbes was gradually increased in degradation areas.We speculate that vegetation degradation could cause the changes about the path of the material circulation in coastal wetland soil.During the process of vegetation restoration in the degraded area,after vegetation restoration,the diversity of soil microbe gradually increased and the community structure changed as a new which was similar with the community structure of vegetation area.In classification levels,the negative relationship was presented between Bacteroidetes and Gracilibacteria,Planctomycetes.The abundance of Gracilibacteria,Planctomycetes and Acidobacteria was positively correlated.In genus taxonomy,the dominate genera,Planctomyces,Exiguobacterium,Citrobacter and Rhodopirellula,were significantly higher than that no-vegetation covering period.And the abundance of those genera,Desulfosarcina,Ilumatobacter,Loktanella,Actibacter and Sulfurovum,were significantly lower than that no-vegetation covering period.RDA analyzed found that the community structure of soil bacteria in the late stage of repair(LPR and LPC)was not affected by environmental factors.We speculate that the community structure was mainly affected by wetland vegetation,owing to substantial metabolic products of vegetation in LPR and LPC.The study of quorum sensing(QS)indicated that A total of twenty-two different QS bacteria were screened from 1050 strains.they belonged to three different phyla,including Proteobacteria,Bacteroidetes and Actinomycetes.Those QS bacteria produced N-acetyl homoserine lactone(AHL)signal molecules which the spectrum of AHLs were from N-hexanoyl-L-homoserine lactone(C6)to N-dodecanoyl-L-Homoserine lactone(C12).The dominant AHL molecules in the root tissues was short-chain C6 and it was medium-chain N-octanoyl-L-homoserine lactone(C8)in rhizosphere soil.The functional study of QS bacteria showed that 72.8% of QS bacteria could form biofilm,68.2% of QS bacteria exhibited anti-human pathogen,9.1% of QS bacteria degraded dimethyl sulfhydryl propionic acid(DMSP),and 18.2% of QS bacteria had the ability to degrade oil.The result of High throughput sequencing in the root environment represented that the OTU abundance in rhizosphere soil was higher than that in root tissues,mostly dominated genera in the root tissue had the salt-tolerance ability.