Study On The Bacterial Community Structure And Correlation With Environmental Factors In The Intertidal Sediments Of Dalian Yellow Sea Coast

Marine microorganisms play an important role in the biogeochemical cycle of elements in marine ecosystems.The intertidal sediments is a special zone between sea and land.The environment is complex and changeable.The interaction of sea and land environmental factors profoundly affects the structure and diversity of microbial communities.This study takes the intertidal sediments along the Yellow Sea coast of Dalian as the research object,selects 30 sediment samples from 15 stations and two different depths,uses High-throughput sequencing technology to analyze the bacterial community structure and diversity,and establishes the microbial community correlation with environmental factors including temperature,pH,TOC,TN,TP,C/N,MC,etc.,to systematically analyze.The main results obtained are as follows:(1)There are differences in the bacterial community structure between different depths.The phylum level and class level of the 25-30 cm samples are significantly higher than the0-5cm samples,and the order of the average relative abundance of the dominant bacterial groups of the samples at different depths is different..The study found 68 phyla,181 classes,469 orders,842 families and 2137 genera.The main dominant categories in the intertidal sediments of the Yellow Sea coast of Dalian are Proteobacteria,Bacteroidetes,Chloroflexi,Actinobacteria,Firmicutes,Acidobacteria,and the abundance of Proteobacteria is absolutely dominant.At the class level,Alphaproteobacteria,Gammaproteobacteria,Bacteroidia,Deltaproteobacteria,and Anaerolineae are the dominant groups.(2)There are differences in bacterial diversity at different depths.The diversity and richness of samples at 25-30 cm are higher than those at 0-5 cm.The average value of Observed-species index of 0-5cm samples is 2202,the average value of Chao1 index is 2343,the average of Shannon index is 8.54,and the average value of Simpson index is 0.9765;the average value of Observed-species index of 25-30 cm samples is 2322,The Chao1 index average is 2532,the Shannon index average is 8.70,and the Simpson index average is 0.9816.?-diversity shows that the samples at the same depth have obvious clustering relationships,and there is overlap and discrimination between the two levels,indicating that the composition of the bacterial community is different,but the overall distance of each sample is relatively small.(3)Bacteria are significantly affected by environmental factors.The composition of bacterial community is most affected by TN and MC;the main influencing factors of bacterial diversity at different depths are different,0-5cm depth samples have a very significant negative correlation with pH,and a significant positive correlation with TN and MC;25-30 cm depth There is a significant positive correlation between the samples and TOC;the abundance of dominant bacteria in the 0-5cm depth sample is more sensitive to the response of environmental factors;and the dominant bacteria also have a synergistic and inhibitory relationship.The intertidal zone along the Yellow Sea coast of Dalian is rich in microbial resources,the bacterial community structure is complex and diverse.This study fills the gaps in the relevant data in this area,and provides basic data and information for the environmental pollution control of intertidal sediments and the geochemical cycle of marine microorganisms.It also laid the foundation for the effective development and utilization of coastal resources and coastal ecological protection.