Bacterial Diversity Of Sponge-derived Bacteria And Screening Of Antibacterialactivity And Functional Genes

Sponges are sessile marine invertebrates and harbour rich microbial communities.Sponge is an important source of bioactive natural products and nearly half of the marine-derived active compounds are isolated from sponges.Almost thousand of natural products have been isolated from sponges and most of them have bioactivities,such as antibacterial,antifungal,antitumor and anti-inflammatory activities.Weihai is located in the north of the Yellow Sea and in the north temperate zone.There are some differences between the temperate sea area and the tropical one in the sponge species,the microorganisms and natural products.Therefore,the study of sponge-drived microorganisms and bioactive compounds from Weihai sea area is good for the discovery of new marine natural products.Culture-dependent method was used to isolate bacteria associated with sponge collected from the coast of Weihai,China.The phylogenetic analysis of the isolated bacterial strains were determined by 16 S rRNA sequencing.Filter paper method was performed to determine the potential antimicrobial activities of the isolated bacterial strains against 7 kinds of different indicator strains.Polyketide synthase(PKS)genes and non-ribosomal peptide synthetases(NRPS)genes of the 16 S rRNA sequencing strains were screened.A totoal of 151 bacterial strains(including 35 actinomycete strains and 116non-actinomycete strains)were isolated from the collected sponges.Fifty-two bacterial strains with different characteristics were selected and sequenced for the 16 S rRNA phylogenetic analysis,and they belonged to 20 genera of 16 families in 4 phyla.They were the Actinobacteria,Proteobacteria,Firmicutes and Bacteroidetes phyla.There were9 genera in Actinobacteria.Besides the dominant genus Streptomyce,other 8 genera were rare actinobacteria.There were 3 genera in Firmicutes,and Bacillus was the dominant genus.There were 3 genera in Proteobacteria,and Vibrio was the dominant genus.There were 2 genera in Bacteroidetes.Of the 151 strains,94 bacterial strains showed activities against at least one of 7different indicator strains.Among them,there were 35 bacterial strains against 2 kinds of indicator bacteria,and 22 against 3,and one against 4 and one against 5,respectively.Of the 52 16 S rRNA sequencing strains,PKS and NRPS genes were observed in 6 and11 of the strains.Among them,3 bacterial strains had both PKS and NRPS genes.Our results suggest that sponge-derived culturable bacteria have good diversity and antimicrobial activity,which may be a potential source for the discovery of novel bioactive substances.