A Study On The Diversity And Preliminary Assessment Of The Antibacteiral Activities Of The Bacteria In The Yellow Sea And East China Sea

Seafloor sediments were the most complex habitats for microbe, and containedabundant bacterial resources and new active substances. In this paper, we took the37sediment samples collected from the Yellow Sea and East China Sea as researchmaterials. A combination of culture-dependent and culture-independent methods was usedto investigate the microbial resources and diversity. In addition, the antibacterial activitieswere detected on part of the bacterial strains.On the one hand,561bacterial strains were isolated from37sediment samples byusing culture-dependent method,421representative strains were identified based on16SrDNA gene sequence analysis. It showed that the bacterial population was composed of4phyla,48genera and121species. Firmicutes as the main dominant phylum contained17genera,68species and282strains. α-proteobacteria (Proteobacteria) contained8genera,13species and39strains; γ-proteobacteria contains6genera,14species and48strains;β-proteobacteria contained1genera,1species and11strains. Bacteroidetes contained12genera,16species and29strains. Actinobacteria contained4genera,7species and22strains. There were7dominant genera such as Bacillus, Psychrobacter, Erythrobacter,Arthrobacter, Brevibacterium, Halobacillus and Planococcus. In addition,14strainsshowed <98%16S rRNA gene sequence similarity values with their closet phylogeneticneighbour and might be potential novel genera or species. Our studies showed thatsediments of the Yellow Sea and the East China Sea had a high bacterial diversity. Thenumber of culturable bacteria isolated from Sea Yellow Sea is higher than the one from EastChina Sea. For East China Sea, more culturable bacteria were isolated from off-shore thanfar-shore.7marine bacterial strains which had strong antimircobial activity to inhibit thegrowth of E. coli, B. subtilis and S.aureus were found and might be potential microbialresources for the development of new antibiotics. Among them,3strains belonged toBacillus, the other3strains belonged to Brevibacterium, Staphylococcus and Paenibacillus.On the other hand, illumina Miseq pyrosequencing technology was used to analyzeprokaryotic microbial community structure and diversity. Totally,3771648optimized readswith the average length of256bp were obtained. There were22746different OUTs basedon the97%sequence similarity.74phylum,243class,469order,736family and983genera were identified by comparing with the data of the RDP database. For bacterialcommunity, Proteobacteria and Planctomycetes as main dominant phylum, accounted for44%and11.2%of the total sequences. γ-Proteobacteria and δ-Proteobacteria were the firstand the second most dominant classes, accounting for21.8%and16.6%. For Archaeacommunity, Crenarchaeota was the most dominan phylum and, Thaumarchaeota was themost dominant class. Based on microbial species richness and shannon index, microbial diversity and species richness of East China Sea were higher than the ones of Yellow Sea.By cluster analysis, microbial community structure from adjacent sites clustered together.RDA analysis showed that temperature, salinity and soil sediment were the main factorsaffecting microbial community structure in marine sediments.