Diversity and antimicrobial activities of cultivable bacteria isolated from Jiaozhou Bay

Abstract:

[Objective] Marine microorganisms have a great potential in producing biologically active secondary metabolites. In order to study the diversity and antimicrobial activity, we explored 9 sediment samples in different observation sites of Jiaozhou bay.[Methods] We used YPD and Z2216E culture medium to isolate bacteria from the sediments; 16S rRNA was sequenced for classification and identification of the isolates. Then, we used Oxford cup method to detect antimicrobial activities of the isolated bacteria against 7 test strains. Lastly, we selected 16 representatives to detect secondary-metabolite biosynthesis genes:PKSI, NRPS, CYP, PhzE, dTGD by PCR specific amplification.[Results] A total of 76 bacterial strains were isolated from Jiaozhou bay; according to the 16S rRNA gene sequence analysis. These strains could be sorted into 11 genera belonging to 8 different families:Aneurinibacillus, Brevibacillus, Microbacterium, Oceanisphae, Bacillus, Marinomonas, Staphylococcus, Kocuria, Arthrobacters, Micrococcus and Pseudoalteromonas. Of them 34 strains showed antimicrobial activity against at least one of the tested strains. All 16 strains had at least one function genes, 5 strains possessed more than three function genes.[Conclusion] Jiaozhou bay area is rich in microbial resources with potential in providing useful secondary metabolites.

Key words:bacteria;antimicrobial activity;functional genes;Jiaozhou Bay