Novel emulsifier from marine microorganism

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Algicidal effect of Red Pigment from the Marine Bacterium Hahella chejuensis strain 96CJ10356 on Red-tide Microalgae

The algicidal effects of red pigment from the marine bacterium Hahella chejuensis strain 96CJ10356 on two species of red-tide microalgae (Cochlodinium polykrikoides and Gyrodinium impudicum) were examined. The isopropanol-soluble crude red pigments with maximum absorptions at 496, and 533.5 nm, were produced. Swimming cell density of C. polykrikoides and G. impudicum decreased to less than 8% of the initial density within 1 h in f/2 medium containing 10 mg/l crude red pigment. After losing their motility, almost all of the cells became round and then expanded and burst. Once cells had become round, none of them recovered to normal vegetative cells within 24 h even if they were transplanted to f/2 medium.1

Hahella chejuensis Pigments Killing Red-tide Microalgae

Algicidal effect of red pigment of a marine bacterium Hahella chejuensis strain 96CJ10356 were tested with Cochlodinium polykrikoides, Gyrodinium impudicum, Heterosigma akashio, Procentrium micans and Alexandium catenella. Among the tested species three species of red-tide microalgae, Cochlodinium polykrikoides, Gyrodinium impudicum and Heterosigma akashio showed strong cell lysis in the presence of red pigment, which had maximum absorptions at 486 and 539 nm. In f/2 medium containing 1 mg/l ethanol-soluble crude red pigment, more than 99.1% of C. polykrikoides cells were lysed within 1 h, At the same conditions, cell lysis density of G. impudicum was 59.7, and H. akashiond 72.9%, respectively. After exposure to this pigment, the algal cells lose their motility, became round, expanded and finally burst.2

Mutagenesis of Hahella chejuensis 96CJ10356 using EMS & Characterization of the Exopolysaccharide Produced by a Mutant Strain

We isolated 155 mutants of Hahella chejuensis 96CJ10356 by EMS（Ethylmethane Sulfonate） mutagenesis method. Hahella chejuensis is a novel marine bacterium that produces a large amount of novel exopolysaccharide (EPS) and red pigment. Hahella chejuensis was cultured in STN liquid medium at 25℃. For mutagenesis, 0.2 M of EMS was added into cell suspension and the mixture was incubated for 1 hr at 25℃. Na2S2O3 was added to stop the reaction of EMS at a final concentration of 6%. The cells were diluted and spread on plates; colonies showing different color or shape were selected. Total 155 mutant strains were preserved in glycerol media (15%, v/v) at –80℃. One of the white mutants, m10356, produced white colored EPS, p-m10356. The mutant m10356 showed higher productivity of exopolysaccharide than wild type, and the exopolysaccharide p-m10356 possessed good emulsify stability under broad range of temperature and pH conditions. Other mutants with diverse colors are going to use for screening of genes in charge of the pigment biosynthesis.2

Novel Exopolysaccharide from Marine Biofilm-Forming Microorganisms

We performed 1) isolation of bacteria from the various slides that had been exposed to natural seawater and the natural biofilms, 2) identification of bacterial strains, 3) estimation of exopolysaccharide-producing ability, 4) characterization of the exopolysaccharide produced by selected strains, and 5) presentation of usage from isolated exopolysaccharide.2

A novel sulfated polysaccharide derived from the marine microalgae Gyrodinium impudicum strain KG03 with immunostimulating activity in vitro

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Phylogenetic Analysis of Protease-Producing Arctic Bacteria

The Arctic is a representative cold habitat that offers good sources of useful enzymes with activity at low temperature. These enzymes are stable after long time storing and some times freeze-thaw cycles. Among the enzymes, protease is important enzyme at medical industry, environment industry, food industry, chemical industry etc. We isolated soil and marine samples from around Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway (79°N, 12°E). The collected samples were diluted in distilled water and seawater, and spread on nutrient and marine agar plates. The samples and plates were transferred to the laboratory at KORDI. They cultured at 10℃, colonies were succeedingly cultured on nutrient and zobell agar plates at 10℃. The pure colonies were inoculated into nutrient and zobell liquid media, and genomic DNA were extracted from the liquid-cultured strains. Phylogenetic analysis using 16S rDNA indicated that the protease-producing bacteria belong to Achromobacter, Arthrobacter, Bacillus, Carnobacterium, Flavobacterium, Paracoccus, Pedobacter, Pseudoaltermonas, Pseudomonas, Psychrobacter, and Staphylococcus species. Many of them are candidates for new species and sources of cold-active protease. We expect that these Arctic bacteria can be used for screening to develop new industrial enzymes.1

Exopolysaccharide from Colorless Mutant of Hahella chejuensis strain 96CJ10356

Red pigment forming Hahella chejuensis 96CJ10356 producde novel viscous exopolysaccharide(EPS), named as EPS-R. In order to prepare colorless EPS, mutants of H. chejuensis 96CJ10356 were developed using by EMS (ethylmetane sulfonate) mutagenesis. Strain m10356, one of non-pigment forming mutants, produced white colored EPS, p-m10356 with higher productivity. The characteristics of p-m10356 such as average molecular masses, sugar compositions, element composition, thermal properties were analyzed. After the effects of salt, pH, temperature, inorganic compounds, and C, N-source were tested, M-m10356 medium was proposed for optimal EPS production. Rheological properties of p-M10356 at various temperatures, concentrations, salts, pH and mixed other polysaccharide were monitored using oscillatory measurement and steady-shear viscosity measurement.2

Utilization of geneticresources and procurement of marine microbial diversity

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