Dissertation > Biological Sciences > Microbiology

Dalian Sea Screening and Identification of culturable marine actinomycetes

Author ShaoYang
Tutor DuChunMei;LiuQiu
School Heilongjiang University
Course Microbiology
Keywords Marine actinobacteria Isolation Antimicrobial activity 16S rDNA Identify Diversity
Type Master's thesis
Year 2011
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Marine sediments have abundant marine microorganisms containing marine actinobacteria which produce various secondary metabolites. In this study, marine actinobacteria were isolated from thirteen different sediment samples of Dalian Sea area. All of samples were pretreated with wet-heating and no-pretreateded respectively, and isolated via nine kinds of selective media adding with two different antibiotics. Totally 165 actinobacteria were isolated, the LSE-SE-2 media was the most efficient culture medium, followed by OM, M2 and HV-2, and the M13 media was the least efficient culture medium. The wet-heating pretreatment method was better than non-pretreated. It was suggested that Dalian Sea area has great potential for acquiring actinobacterial.All isolated strains were tested for antimicrobial activity using agar diffusion method. The result showed that there were 85 antimicrobial actinobacteria strains of them. 26 strains showed activity against Escherichia coli, which was 16.4% of the total isolates. 85 strains showed good activity against Staphylococcus aureus, which was 51.5% of the total isolates. However, only 6 strains showed activity against Fusarium oxysporum, which was 3.6%of the total isolates.16S rDNA genes of 95 isolated strains with special phenotype or strong antimicrobial activities were sequenced. The phylogenetic analysis based on 16S rDNA gene sequencing showed that the 95 strains belonged to genera Streptomyces and Nocardiopsis. To better understand the cultural actinobacteria diversity, we attempted to construct several N-J phylogenetic trees with the 95 sequenced strains. The result discovered that the 95 strains belonged to 37 groups of Streptomyces and 4 groups of Nocardiopsis. Two N-J phylogenetic trees were constructed with different antibacterial activity strains sequences separately. The result indicated that sequenced strains which against Escherichia coli were classified to 13 groups of Streptomyces and 3 groups of Nocardiopsis and sequenced strains which against Staphylococcus aureus belonged to 29 groups of Streptomyces and 4 groups of Nocardiopsis. On the basis of morphological characteristics, the cultural properties, physiological and biochemical features together with the 16S rDNA analysis, there were 16 strains to be identified. The identical result proved that 16 actinobacterial strains were Streptomyces matensis(HA5)、Streptomyces albogriseolus(HC7)、Streptomyces globisporus(M8)、Streptomyces hawaiiensis(M76)、Streptomyces macrosporus(M77)、Nocardiopsis dassonville(iMH28,PH26)、Streptomyces parvus(PH33)、Nocardiopsis terrae(HV3)、Streptomyces fimicarius(HW27)、Streptomyces pluricolorescens(HW66)、Streptomyces fradiae(HL9)、Nocardiopsis aegyptia(HE9)、Streptomyces rubiginosohelvolu(sHE16)、Streptomyces coelicoflavus(HE18)、Streptomyces cinereorectus(HE55), separately.

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