• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.225-229
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• 2003

Each oxidoreductase activity of the aerobic respiratory chain-linked NADH oxidase system in the marine bacterium Pseudomonas nautica was stimulated by monovalent cations including $Na^+,\;Li^+,\;and\;K^+$. In the presence of NADH or deamino-NADH as electron donors, $GH_2$ formation was approximately 1.3-fold higher in the presense of 0.08 M of $Na^+\;than\;K^+$, Whereas the other reductase activities were not significantly higher in $Na^+\;than\;K^+$. The optimal pH of NADH (or deamino-NADH):ubiquinone-1 oxidoreductase was 9.0 in the presence of 0.08 M NaCl. The activity of NADH (or deamino-NADH):ubiquinone-1 oxidoreductase was inhibited by about 33% with $60{\mu}M$ 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). The activity of NADH (deamino-NADH): ubiquinone-1 oxidoreductase was inhibited by about 32 to 38% with $80{\mu}M$ rotenone, whereas the activity was highly resistant to capsaicin. On the other hand, electron transfer from NADH or deamino-NADH to ubiquinone-1 generated a membrane potential (${\Delta}{\psi}$) which was larger in the presence of $Na^+$ than that observed in the absence of $Na^+$. The ${\Delta}{\psi}$ was almost completely collapsed by $5{\mu}M$ carbonylcyanide m-chlorophenylhydrazone(CCCP), and approximately 50% inhibited by $100{\mu}M$ rotenone, or $60{\mu}M$ 2-heptyl-4-hydroxyquinoline (HQNO). Also, HQNO made the ${\Delta}{\psi}$ very unstable. The results suggest that the enzymatic and energetic properties of the NADH:ubiquinone oxidoreductase of P. nautica are quite different, compared with those of other marine halophilic bacteria.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1483-1490
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• 2007

A Gram-negative, motile by tuft flagella, obligately aerobic chemoorganoheterotrophic, sphere-form bacterium, designated $IMCC3135^T$, was isolated from the Antarctic surface seawater of King George Island, West Antarctica. The strain was mesophilic, neutrophilic, and requiring NaCl for growth, but neither halophilic nor halotolerant. The 16S rRNA gene sequence analysis indicated that the strain was most closely related to genera of the order Chromatiales in the class Gammaproteobacteria. The most closely related genera showed less than 90% 16S rRNA gene sequence similarity and included Thioalkalispira (89.9%), Thioalkalivibrio (88.0%-89.5%), Ectothiorhodospira (87.9%-89.3%), Chromatium (88.3%-88.9%), and Lamprocystis (87.7%-88.9%), which represent three different families of the order Chromatiales. Phylogenetic analyses showed that this Antarctic strain represented a distinct phylogenetic lineage in the order Chromatiales and could not be assigned to any of the defined families in the order. Phenotypic characteristics, including primarily non-phototrophic, non-alkaliphilic, non-halophilic, and obligately aerobic chemoheterotrophic properties, differentiated the strain from other related genera. The very low sequence similarities (<90%) and distant relationships between the strain and members of the order suggested that the strain merited classification as a novel genus within a novel family in the order Chromatiales. On the basis of these taxonomic traits, a novel genus and species is proposed, Granulosicoccus antarcticus gen. nov., sp. nov., in a new family Granulosicoccaceae fam. nov. Strain $IMCC3135^T\;(=KCCM42676^T=NBRC\;102684^T)$ is the type strain of Granulosicoccus antarcticus.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.391-396
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• 1996

The Gram-negative marine bacterium Marinomonas vaga, which requires 0.5 M NaCl concentration for optimal growth, is slightly halophilic. The growth of M vaga was highly resistant to the proton conductor, carbonyl cyanide m-chlorophenylhydrazone (CCCP) under alkaline pH conditions (pH 8.5) but very sensitive to CCCP under acidic pH conditions (pH 6.5). These results suggest that the respiratory chain-linked NADH oxidase system of M. vaga may lead to generation of a $Na^{+}$ electrochemical gradient. In order to examine the existence of $Na^{+}$-stimulated NADH oxidase in M. vaga, membrane fractions were prepared by the osmotic lysis method. The membrane-bound NADH oxidase oxidized both NADH and deamino-NADH as substrates and required $Na^{+}$ for maximum activity. The maximum activity of NADH oxidase was obtained at about pH 8.5 in the presence of 0.2 M NaCl. The site of $Na^{+}$-dependent activation in the NADH oxidase system was at the NADH:quinone oxidoreductase segment. The NADH oxidase and NADH:quinone oxidoreductase were very sensitive to the respiratory chain inhibitor, 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) in the presence of 0.2 M NaCl but highly resistant to another respiratory inhibitor, rotenone. Based on these findings, we conclude that M. vaga possesses the $Na^{+}$-dependent NADH:quinone oxidoreductase that may function as an electrogenic $Na^{+}$ pump.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.108-113
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• 2007

In this study, a halophilic protease-producing bacterium was isolated from the west seaside mud flats of Korea. The 16S rDNA nucleotide sequences of the isolate showed 99.5% sequence homology with those of Vibrio vulnificus and Vibrio fluvialis; therefore, the isolate was named Vibrio sp. YH-127. Gram staining and the carbohydrate metabolism test results supported the isolate as one from the Vibrio family. Optimum condition for the cell growth and for the protease activity were obtained when the isolate was cultured at 25$^{\circ}C$ and pH 7.0, with the salt concentration of the medium similar to that of sea water. Finally, the addition of Mg$^{++}$ ions into medium increases protease activity suggesting that the protease produced by the isolate was a metalloprotease.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1933-1942
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• 2016

A novel ${\alpha}-glucoside$ hydrolase (named PspAG97A) from glycoside hydrolase family 97 (GH97) was cloned from the deep-sea bacterium Pseudoalteromonas sp. K8, which was screened from the sediment of Kongsfjorden. Sequence analysis showed that PspAG97A belonged to GH97, and shared 41% sequence identity with the characterized ${\alpha}-glucoside$ BtGH97a. PspAG97A possessed three key catalytically related glutamate residues. Mutation of the glutamate residues indicated that PspAG97A belonged to the inverting subfamily of GH97. PspAG97A showed significant reversibility against changes in salt concentration. It exhibited halophilic ability and improved thermostability in NaCl solution, with maximal activity at 1.0 M NaCl/KCl, and retained more than 80% activity at NaCl concentrations ranging from 0.8 to 2.0 M for over 50 h. Furthermore, PspAG97A hydrolyzed not only ${\alpha}-1,4-glucosidic$ linkage, but also ${\alpha}-1,6-$ and ${\alpha}-1,2-glucosidic$ linkages. Interestingly, PspAG97A possessed high catalytic efficiency for long-chain substrates with ${\alpha}-1,6-linkage$. These characteristics are clearly different from other known ${\alpha}-glucoside$ hydrolases in GH97, implying that PspAG97A is a unique ${\alpha}-glucoside$ hydrolase of GH97.

• Journal of Life Science
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• v.12 no.6
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• pp.759-764
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• 2002

A halophilic bacterium for the production of the immunostimulant was isolated from domestic marine, it was identified as Burkholderia sp. IS-203. The optimal conditions for the production of the immunostimulant were 1 % dextrose and 1 % yeast extract in artificial sea water for carbon and nitrogen sources, respectively. The initial pH and growth temperature for the prodution were 8.0 and $30^{\circ}C$ under the presence of oxygen, respectively.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.118-124
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• 2005

In this research, we examined the effect of NaCl on the growth, energy metabolism, and proton motive force of Halomonas salina, and the effect of compatible solutes on the bacterium growing in the high salinity environment. H. salina was isolated from seawater and identified by 16srDNA sequencing. The growth of H. salina was not enhanced by the addition of external compatible solutes (choline and betaine) in the high salinity environment. The resting cells of H. salina absorbed more glucose in the presence of 2.0 M NaCl than in its absence. H. salina did not grow in the medium with either KCl, RbCl, CsCl, $Na_2SO_4$, or $NaNO_3$, in place of NaCl. The optimal concentration of NaCl for the growth of H. salina ranged from 1.4 M to 2.5 M, and the growth yield was decreased in the presence of NaCl below 1.4M and above 2.5M. The activity of isocitrate dehydrogenase, pyruvate dehydrogenase, and malate dehydrogenase of H. salina was not inhibited by NaCl in in vitro test. The proton translocation of H. salina was detected in the presence of NaCl only. These results indicate that NaCl is absolutely required for the normal growth and energy metabolism of H. salina, but the bacterial growth is not enhanced by the compatible solutes added to the growth medium.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.41-47
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• 2004

This study was performed to investigate the antimicrobial effects of hetero-chitosans and their oligosaccharides on the halophilic bacterium, Vibrio parahaemolyticus. Nine classes of hetero-chitosan oligosaccharides were prepared based on their molecular weights, using an ultrafiltration membrane reactor system with chitosanase and celluase, from partially different deacetylated chitosans, 90%, 75%, and 50% deacetylated chitosan, respectively. Thirty-two strains of V. parahaemolyticus were isolated from various marine organisms such as shellfish, shrimps, octopus, and seabirds. Seventy-five percent deacetylated chitosan showed the highest antimicrobial acitivity. The minimal inhibitory concentration (MIC) was 0.5 mg/ml on 14 strains of V. parahaemolyticus, and MIC of the rest strains (18 strains) was 1.0 mg/ml. In addition, MIC of most hetero-chitosan oligosaccharides was 8.0 mg/ml. The results revealed that the antimicrobial effects of hetero-chitosans and their oligosaccharides against V. parahaemolyticus depend on the degree of deacetylation, their molecular weights, and strains tested.

• Journal of Life Science
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• v.10 no.1
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• pp.94-100
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• 2000

Urease is an important microbial enzyme and its production is a marker to predict potential pathogenicity. An unusual halophilic bacterium producing urease was isolated from sea product and identified as Vibrio parahaemolyticus KH410. Its biochemical properties were indole negative, gelatin positive, sodium citrate positive and Kanagawa positive whereas other characteristics were identical as the standard strain except it showed a positive reaction on Christensen's urea agar. V. parahaemolyticus urease production was directly related to urea concentration. The production of urease was noticeable by the addition of 0.2% urea, 0.5% glucose, 2% NaCl in LB broth, and the initial pH of 5.5. The maximum production reached after 6 hr of incubation at 37$^{\circ}C$. However, NiCl2, metal ions, phosphorus did not affect production of urease.

• KSBB Journal
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• v.11 no.1
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• pp.37-45
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• 1996

Marine bacterial strain, highly effective agar degrading, was isolated from south sea of Korea and was identified as Pseudomonas sp. This strain was named Halophilic Pseudomonas sp. W7 and accumulated an extracellular agarase which showed a high level of enzyme activity in the presence of agar and agarose. This extracellular agarase was purified by anion-exchange chromatography and gel filtration. Purified agarase showed a single protein band upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis and its molecular weight was estimated to be about 89KDa. The agarase gene was cloned into Escherichia coli JM83 using the plasmid vector pUC19. DNA fragments(3.7, 3.0Kb) of Hind III-digested chromosomal DNA of Pseudomonas sp. W7 was inserted into the Hind III site of pUC19. Selected transformants, E. coli JM83/pSWl 000000and E. coli JM83/pSW3, produced agarase and this agarase was accumulated In the cytoplasmic space.