Dissertation
Dissertation > Biological Sciences > Microbiology > Microbial biochemistry

Research on the Metabolites with Antimicrobial Activity from Marine Microorganism from the East Sea

Author WangCan
Tutor ZhangXingQun
School Donghua University
Course Organic Chemistry
Keywords marine microorganism the metabolites with antimicrobial activity strain identification NRPSs purification
CLC Q936
Type Master's thesis
Year 2009
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With the wide use of antibiotics and other antibacterial agents, bacteria resistant to many antibiotics is increasing seriously, for example, Methicillin-resistant Staphylococcus aureus (MRSA) which is resistant to most antibiotics is increasing rapidly and has become the vital pathogenic bacteria in the clinic. A renewed effort should be made to seek new antibiotics. Microorganism resources in land once were the main source for screening for antibiotic. However, with the research going on, it is becoming more and more dificult to find new antibiotics. It is necessary to seek for the new medicine source. Since the specific living environment, marine microorganisms have unique heredity background and metabolite pathways, and synthesize some distinct antibiotics in structures. Therefor it has significance for antibiotics screening from marine microorganism. And the marine microorganisms have attracted considerable attention because of chemical unique, rich physiological properties and thus potential as important drugs of their metabolites.Many kinds of samples, in cluding sea mud and sea vertebrata were collected from East Sea from different region. It is greatly influenced by the composition of medium and culture condition on the production of the metabolites with antimicrobial activity and the growth of marine microorganism.446 strains marine bacteria,8 strains marine actinomycetes and 53 strains marine fungi were isolated from the sea mud. Total 36 culturable microorganisms,28 marine bacteria,1 strains marine actinomycetes and 7 strains marine fungi were isolated from the gills, stomachs or intestines of deep-sea shark,of which 5 strains were from gills and 31 strains were from stomachs or intestines.Among them,there were 7 strains of fungi (19%),1 strains of actinomycetes (3%) and 28 strains of bacteria (78%). Their antibiotic activities against six microorganisms (Bacillus subtilis、Staphylococcus aureus、Escherichia coli、Pseudomonas aeruginose、Enterobacter aerogenes、Candida albicans) were assayed Oxford Cup method.The isolated strains from the gills, stomachs or intestines of deep-sea shark is identified through morphological, physiological and biochemical experiment,16S rRNA sequence analysis and phylogenetic analysis. It will provide some basic information and some bioactive strains for the discovery of the metabolites with antimicrobial activity from sea.In this study, a pair of degenerate oligonucleotide primers, disigned for amplification A domain in NRPSs, had been employed to screen NRPSs gene fragments from the gills, stomachs or intestines of deep-sea shark. Our purpose was to develop a method to access NRPSs gene diversity in sea. This would open up the possibilities of the secondary metabolites and as the basis for a search for attractive antibiotic biosynthesis genes that could be used in the heterogenous expression and combinatorial biosynthesis. Furthermore, the amplified NRPSs gene fragments can also be used as homologous hybridization probes to detect the clones harbored NRPSs gene clusters.One strain is screened from the gills,stomachs or intestines of deep-sea shark. The metabolites produced by the strain have high antimicrobial activity and broad antimicrobial spectrum. The strain and its metabolites are researched. The results show that the culture has a broad antimicrobial spectrum against some gram-negative and gram-positive bacteria, and moulds, especially against Enterobacter aerogenes, Staphylococcus aureus and Candida albicans. The physical and chemical properies of the metabolites with antimicrobial activity of Y9, the results showed it has good stability against temperature and acidity, but not alkali. The metabolites with antimicrobial activity are identified which is not a kind of protein, and it can be dissolved in methyl alcohol and ethanol.

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