• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.818-821
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• 2011

An agar-degrading bacterium was isolated from the guts of spiny turban shells. It was identified as a Pseudoalteromonas species and named Pseudoalteromonas sp. JYBCL 1. The viscosity of the inoculated agar medium decreased by more than 60% after 20 h cultivation. The agarase produced by the isolate had optimal activities at $35^{\circ}C$ and pH 7. The enzyme had extremely strong resistance to ionic stress compared with other known agarases. Its molecular mass was estimated at about 60 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The agarase could saccharify Gelidium amansii directly, with an efficiency about half that compared with agar saccharification.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.259-263
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• 2012

To isolate an alginate-degrading bacterium, we conducted a single colony isolation using a solid medium containing alginate as the sole carbon source. A marine bacterium Y-4 capable of degrading alginate was isolated from seawater. The strain was identified to be Pseudoalteromonas sp., based on morphological, biochemical, 16S rDNA homology, and phylogenetic analyses. Moreover, Pseudoalteromonas sp. Y-4 exhibited alginate lyase activity in the presence of 4% alginate even though many known alginate-degrading bacteria degrade in the range of 0.5-1% alginate. The optimum culture conditions for the Y-4 strain were 2% alginate, pH 8.0, and 3% NaCl at $30^{\circ}C$. The highest alginate lyase activity was also observed under the same conditions. To our knowledge, this is the first reported isolation of a marine bacterium degrading high concentrations of alginate.

• Journal of Life Science
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• v.19 no.6
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• pp.787-792
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• 2009

In this study, protease-producing bacteria were isolated from the marine sedimentary layer in coastal Jeju. We isolated 2 protease producing strains (SK-2 and SK-125) and tested their protesase producing activities. Gram staining and BIOLOG of isolated strains revealed that strains SK-2 and SK-125 belong to Bacillus and Pseudoalteromonas families, respectively. The 16S rDNA nucleotide sequences analyses of the isolated strains showed 99% sequence homology with those of Bacillus sp. and Pseudoalteromonas sp.; therefore, the isolated strains SK-2 and SK-125 were named Bacillus sp. SK-2 and Pseudoalteromonas sp. SK-125, respectively. The optimum conditions for the cell growth of protease activities were obtained when the both isolates were cultured at $30^{\circ}C$, 96 hrs and pH $7{\sim}8$.

• Journal of Life Science
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• v.19 no.3
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• pp.366-372
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• 2009

In the course of screening of useful enzyme-producing microorganisms from marine sedimentary layers, we isolated 2 amylase producing strains and tested their amylase producing activities. Analyses of 16S rDNA sequences and biochemical methods (BIOLOG) of two isolates showed that they were confirmed to be a gram positive Bacillus sp. and gram negative Pseudoalteromonas sp., respectively. Excellent amylase producing strains were termed Bacillus sp. ST-63 and Pseudoalteromonas sp. ST-140, and further studies were conducted on their amylase producing characteristics. Optimum conditions for cell growth in amylase activity were obtained when the isolate (Bacillus sp. ST-63 and Pseudoalteromonas sp. ST-140) was cultured at $30^{\circ}C$ and pH $7{\sim}8$.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.346-351
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• 2010

The purpose of this work was to investigate the characteristics of a biosurfactant-producing bacterium isolated from crude-oil contaminated soils. During the incubation of strain HK-3 with 1% crude-oil, bacterial growth pattern, the amount of biosurfactant production, and pH changes were monitored. In order to examine the effect of supplemented carbons on the production of biosurfactant, cultivation of HK-3 cells in BH media with different carbons (e.g. glucose, dextrose, mannitol, citrate, or acetate) revealed that the production of biosurfactant reached the maximal level at the 72 h incubation with mannitol, which the area of clear zone was measured to approximately 7.64 $cm^2$. Identification test using the BIOLOG system, morphology study based on scanning electron microscopy and the 16S rRNA sequence-based phylogenetic analysis assigned strain HK-3 to a Pseudoalteromonas species, designated as Pseudoalteromonas sp. HK-3 which was registered in GenBank as [FJ477041].

• Journal of Life Science
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• v.18 no.12
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• pp.1752-1757
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• 2008

Three marine bacteria producing pigments were isolated from seawater of Jeju-Do and local solar saltern in Korea. Based on phenotypic characteristics and 16S rRNA sequence analysis, the strains were identified as Pseudoalteromonas spp., which produced red (Ju11-1), yellow (Ju14), and orange (TA20) pigments. The pigments showed UV absorption maxima at 537, 378 and 387 nm, respectively. The strains were growing well on Marine broth 2216 culture medium. The productivity of pigments reached the maximum value after 28 hours (Ju11-1, Ju14) and 24 hours (TA20) at $30^{\circ}C$, 2% NaCl and pH 6-7. The best pigment production of strains were supported by 1% of lactose (Ju11-1) and maltose (Ju14, TA20) as a carbon source and 1% of beef extract as a nitrogen source.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.75-80
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• 2015

Pseudoalteromonas donghaensis HJ51, isolated from the East Sea, has been reported as a novel strain to produce extracellular protease. Crude supernatant was used to determine optimal activity and optimal production conditions for the enzyme. It was found that the optimal temperature and pH of the protease were $40^{\circ}C$ and pH 7.5-10.5, respectively. The enzyme activity was kept to 88% at the pH 11. In metal requirement analysis, the enzyme exhibited the highest activity when 10 mM $Fe^{3+}$ was supplied. While supplementation of additional carbon sources used in study showed no positive effect on cell growth and enzyme activity, the addition of beef extract, tryptone, or casamino acids instead of peptone of PY-ASW containing 1% glucose increased enzyme production to 21, 7, 4%, respectively. Taken together these properties, the enzyme produced from P. donghaensis HJ51 can be applied to the industries that require protease activity under alkaline pH and low temperature.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.118-121
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• 2005

Arylsulfatase cloned from a marine bacterium, Pseudoalteromonas carrageenovora, was over-expressed in Escherichia coli. Most of the recombinant arylsulfatase was found in the cell lysate with induction up to $10{\mu}M$ IPTG. However, enzyme activity was observed both in the culture supernatant and cell lysate by induction with IPTG concentration of $50-5,000{\mu}M$. Most of the recombinant enzyme was localized in the periplasmic space with $10{\mu}M$ IPTG induction, while half of the enzyme was distributed in the periplasmic space with $50{\mu}M$ IPTG induction. Cell growth and arylsulfatase activity did not change with the induction time, and the level of recombinant arylsulfatase expression was maintained at 4-5 U/mL after 6 to 14 hr of culture.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.272-278
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• 2007

Proteases are enzymes that break peptide bonds between amino acids of other proteins and occupy a crucial position with respect to their applications in both physiological and commercial fields. In order to screen new source of protease, bacteria producing extracellular proteases at low temperature were isolated from deep sea water of East Sea, Korea. A bacterium showing the best growth rate and production of an extracellular protease at low temperature was designated HJ 47. The DNA sequence analysis of the 16S rRNA gene, phenotypic tests and morphology led to the placement of this organism in the genus Pseudoalteromonas. Although maximal growth was observed at $37^{\circ}C$, enzyme production per culture time was maximum at $20^{\circ}C$. At this temperature, extracellluar protease production was detected from the end of the exponential phage to stationary phase, and maximal at 15 hours after initial production. The optimum temperature and pH of the protease were found to be $35^{\circ}C$ and 8.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.55.1-55.1
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• 2008