Species Biodiversity And Metabolites Study Of The Symbiotic/Epiphyte Bacteria From Euphausia Superba

Marine symbiotic and epiphyte microorganisms are one hot focus to discover novel marine lead compounds. Euphausia superba, as a key species in the ecosystem of Antarctic Ocean, has a unique way of life, and a large number of microbial flora in vivo, and it is regarded as a new treasury for exploring new marine microbial resource.The species abundance and diversity of gut microbiome of Euphausia superba were analyzed by culture-independent high-throughput sequencing and by microbial pure culture method, the cultured intestinal bacteria were isolated and phylogenetic analysis of the bacteria was performed. The potential of new species was identified, and its metabolites diversity was analyzed. Based on the results obtained, the symbiotic and epiphyte bacteria of Euphausia superba contain total 95 OTU at 97% similarity level, they were made up of 7 phyla altoghther, including Firmicutes, Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria, Chlorobi, Planctomycetes. There were 70 genera and 95 kinds of species matched with the database records, in addition to 7% unknown species and a large number of uncultured microorganisms. Firmicutes was the dominant bacterial group, accounting for 92% of the total, and 32 OTU; Proteobacteria was the second dominant bacterial group accounting for 5.10%, and 41 OTU. In all groups, total 10 dominant genera includes Arthrobacter sp., Bacillus sp., Carnobacterium sp., Lactococcus sp., Lysinibacillus sp., Leuconostoc sp., Pseudomonas sp., Solibacillus sp., Streptococcus sp., and Vibrio sp.. Total 81 cultivable microbial strains were isolated, belonging to 36 genus including Mobilicoccus sp., Rhodococcus sp., Arthrobacter sp. and Microbacterium sp. et al. Among them, Proteobacteria was the most dominant group, accounting for 68%; Actinobacteria was the seconde dominant group, accounting for 25%; Bacteroidetes 5% and Firmicutes was the least, only accounting for 2%. Phylogenetic analysis based on 16 S r RNA gene sequences showed three strain, NJES-16, NJES-13, NJES-23, were 97.71%, 75.72%, 95.88%, indicating they were potential new species. The polyphasic taxonomy analysis of NJES-13 strain was performed. And metabolites diversity was analyzed by LC-TOF MS method.The symbiotic/epiphyte intestinal flora of Euphausia superba is rich in species diversity, containing numbers of unknown species, and has the good potential to discovery new and active microbial natural products. Through further research, the understanding of the Euphausia superba symbiotic/epiphyte bacteria as a new microbial resource will be performed. It may also find a new way for comprehensive utilization of the biological resources of Euphausia superba by discrovering new active marine metabolites from their symbiotic/epiphyte bacteria.