The Bacteria Diversity And Antimicrobial Activity Analysis Of Jiaozhou Bay Sediment

With characteristics such as high salt,high pressure,low temperature and rare nutrition in Marine environment,Marine microorganisms have its unique metabolic mechanism for long-term adapting to the complex ocean environment.Jiaozhou bay is a semi-closed gulf,this paper analyzed the bacterial diversity and bacteriostatic activity in jiaozhou bay sediments.We used YPD,2216 E,Gauserime agar and M6 culture medium to isolate bacteria from the 9 sediments based on dilution-plate method.A total of 208 strains were isolated,through differentiating colony morphology and cell morphology of srains,76 isolates were obtained.Results from the 16 S rDNA sequence analysis indicated that the strains could be sorted into 11 genera belonging to 8 different family: Aneurinibacillus,Brevibacillus,Microbacterium,Oceanisphae,Bacillus,Marinomonas,Staphylococcus,Kocuria,Micrococcus,Pseudoalteromonas,showing the microbial diversity of Jiaozhou bay sediment.Using traditional screening method screened the bacteriostatic activity of isolates,with Escherichia coli,Pseudomonas aeruginosa,Bacillus subtilis,Micrococcus luteus,Candida albicans,Klebsiella pneumoniae and Enterobacter aerogenes as indicator bacteria.Results shows 44.7% of strains showed antimicrobial activity against at least one of tested pathogenic organisms.Lastly,we selected 16 representatives to detect secondary-metabolite biosynthesis genes: PKSI,PKSII,halo,NRPS,CYP,PhzE,dTGD by PCR specific amplification.PKSII,halo genes failed to swell out for some reason,the 16 strains have at least one function genes of the rest,proving the potential of bioactive secondary metabolites inJiaozhou bay microorganisms.Molecular biology identification,phenotypic characteristics identification,physiological and biochemical identification of polyphasic taxonomy identification method has carried on the classification to LWYT1014,LWYT0409 identification.We identified that LWYT0409 stiain is Bacillus methylotrophicus,LWYT1014 strain is Bacillus anthracis.For further study of LWYT0409 strain's antibacterial compounds,we explored the physical and chemical properties,separation condition,fermentation condition,etc.Results showed that the antibacterial compounds have high thermal stability,however,are sensitive to pH.Many methods for antibacterial compounds separation had been tried,such as acid precipitation,agent solution extraction method,thin layer chromatography,etc,the suitable extraction agent,developing solvent in separation of antibacterial compounds had been found,laying a foundation for further separation and purification of antibacterial compounds.