• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.27-36
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• 2022

Ever since bioplastics were globally introduced to a wide range of industries, the disposal of used products made with bioplastics has become an issue inseparable from their application. Unlike petroleum-based plastics, bioplastics can be completely decomposed into water and carbon dioxide by microorganisms in a relatively short time, which is an advantage. However, there is little information on the specific degraders and accelerating factors for biodegradation. To elucidate a new strain for biodegrading poly-3-hydroxybutyrate (PHB), we screened out one PHB-degrading bacterium, Microbulbifer sp. SOL03, which is the first reported strain from the Microbulbifer genus to show PHB degradation activity, although Microbulbifer species are known to be complex carbohydrate degraders found in high-salt environments. In this study, we evaluated its biodegradability using solid- and liquid-based methods in addition to examining the changes in physical properties throughout the biodegradation process. Furthermore, we established the optimal conditions for biodegradation with respect to temperature, salt concentration, and additional carbon and nitrogen sources; accordingly, a temperature of 37℃ with the addition of 3% NaCl without additional carbon sources, was determined to be optimal. In summary, we found that Microbulbifer sp. SOL03 showed a PHB degradation yield of almost 97% after 10 days. To the best of our knowledge, this is the first study to investigate the potent bioplastic degradation activity of Microbulbifer sp., and we believe that it can contribute to the development of bioplastics from application to disposal.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.527-533
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• 2017

As the clothing industry has advanced, dyeing technologies using various dyes have been developed. In recent years, interest in natural pigments has been increasing because of the negative impact of synthetic pigment on human health; therefore, development and application of microbial pigments is demanded. In this study, the dyeing effects on multifiber fabrics and biological activity were assessed using violet natural pigment from the marine bacterium, Microbulbifer sp. PPB12. The violet pigment produced by cultivation of Microbulbifer sp. PPB12 using Marine broth 2216 for 3 days was extracted using ethanol. Once dissolved in 20% ethanol, the violet pigment could be used to dye bleached cotton, diacetate, and especially polyamide. The optimal temperature, time, pH, and bath ratio under the dyeing conditions were $80^{\circ}C-90^{\circ}C$, more than 1 hour, pH 4-6, and 1:25, respectively. The mordant treatment was more suitable for color expression when $Na_2SO_4$ was used after 10 minutes of dyeing, but no significant difference was observed from untreated samples. The violet pigment also showed antibacterial activity against B. subtilis. The results of the present study indicate that the marine bacterial pigment could be an alternative for textile dyeing as a natural dye with antibacterial activity.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.186-191
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• 2011

An agar-degrading enzyme-producing strain was isolated from seawater. The isolate was identified as Microbulbifer sp. SD-1 by 16S rRNA sequencing analysis. The optimal pH and temperature for growth were 6.0 and $30^{\circ}C$, respectively, and growth was possible at pH 9.0 and $60^{\circ}C$. The isolate required 5% NaCl for optimal growth and showed 45% growth activity without NaCl. Agar concentrations of 0-0.4% in the medium did not affect growth. Thin-layer chromatography analysis revealed that this strain could degrade agar into a monosaccharide and oligosaccharide, which may have industrial applications.

• Journal of Life Science
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• v.22 no.5
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• pp.627-633
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• 2012

$Microbulbifer$ sp. AJ-3 was used to acquire the degrading products from $Capsosiphon$ $fulvescens$ (DPCF), which were investigated to determine its physiological activities. A crude enzyme extract from $Microbulbifer$ sp. AJ-3 hydrolyzes polysaccharide substrates such as agar, agarose, alginic acid, fucoidan, laminaran, starch, and chitin. Among them, agarose, laminaran, and alginic acid showed higher activities, especially alginic acid. The antioxidant activity of DPCF was measured by using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and superoxide dismutase (SOD)-like activities and were about 32% and 93% at 2 mg/ml, respectively. In addition, the nitrite-scavenging activity of DPCF was about 82%, 53%, and 12% at pH levels of 1.2, 3.0, and 6.0, respectively. To determine the influence of DPCF on alcohol metabolism, the generating activity of reduced-nicotinamide adenine dinucleotide (NADH) by alcohol dehydrogenase (ADH) was measured. The facilitating rate of ADH activity by DPCF was 130% at 2 mg/ml. The tyrosinase inhibitory activity of DPCF was slightly increased in a dose-dependent manner and was about 28% at 2 mg/ml. These results indicated that the enzymatic products from DPCF have a strong antioxidant, nitrite scavenging, and alcohol metabolizing activity.

• Journal of Life Science
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• v.22 no.6
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• pp.751-759
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• 2012

Microbulbifer sp. was used to acquire the degrading products from Ecklonia cava (DPEC) and the products were investigated to determine the physiological activities. Firstly, 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity and superoxide dismutase (SOD) assay were about 84.1% and 89.6% at 2.5 mg/ml, respectively. In addition, nitrite scavenging ability was shown to be 56.3% at 0.5 mg/ml on pH 1.2. ${\alpha}$-Glucosidase inhibitory activity was increased in a dose-dependent manner and was about 58.7% at 2.5 mg/ml. To determine the influence of DPEC on alcohol metabolism, the generating activity of reduced-nicotinamide adenine dinucleotide (NADH) by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) were measured. Facilitating rates of ADH and ALDH activities by DPEC were 123.3% and 215.2% at 2.5 mg/ml, respectively. For analyses of anti-wrinkling and whitening effects, its elastase and tyrosinase inhibitory activities were measured and were about 73.1% and 42.2% at 2.5 mg/ml, respectively. These results indicated that DPEC has valuable biological attributes owing to its antioxidant, nitrite scavenging, and alcohol metabolizing activities and ${\alpha}$-glucosidase, elastase, and tyrosinase inhibitory activities.

• Microbiology and Biotechnology Letters
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• v.45 no.2
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• pp.124-132
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• 2017

Microbial secondary metabolites of marine organisms are regarded as major sources of structurally and biologically novel compounds with numerous potential uses. Sponge-microbe associations are among the most interesting sources for exploring bioactive compounds. In this study, the bacterial strain Microbulbifer sp. (127CP7-12) was isolated from the Asian marine sponge Hymeniacidon sinapium collected at an intertidal zone on the west coast of Korea. Cultured bacteria produced a violet pigment, and optimal culture conditions for violet pigment production were investigated. Maximum production of the violet pigment from the strain culture was observed under the conditions of $25^{\circ}C$, pH 6.0, and 3% NaCl. Acetone provided better extraction of the pigment from fermented broth compared with ethanol and methanol. The proposed structure of the major component in the extracted crude pigment was determined via high-performance liquid chromatography, nuclear magnetic resonance, mass spectrometry, and UV spectra analyses, which showed that the metabolite was the promising bioactive compound violacein. This study describes the examination of marine bioactive materials from microbe-engaged metabolites and the ecological implications of the sponge-microbe association in a changing ocean.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.913-922
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• 2013

An agar-degrading bacterium was isolated from red seaweed (Gelidium amansii) on a natural seawater agar plate, and identified as Saccharophagus sp. AG21. The ${\beta}$-agarase gene from Saccharophagus sp. AG21 (agy1) was screened by long and accurate (LA)-PCR. The predicted sequence has a 1,908 bp open reading frame encoding 636 amino acids (aa), and includes a glycosyl hydrolase family 16 (GH16) ${\beta}$-agarase module and two carbohydrate binding modules of family 6 (CBM6). The deduced aa sequence showed 93.7% and 84.9% similarity to ${\beta}$-agarase of Saccharophagus degradans and Microbulbifer agarilyticus, respectively. The mature agy1 was cloned and overexpressed as a His-tagged recombinant ${\beta}$-agarase (rAgy1) in Escherichia coli, and had a predicted molecular mass of 69 kDa and an isoelectric point of 4.5. rAgy1 showed optimum activity at $55^{\circ}C$ and pH 7.6, and had a specific activity of 85 U/mg. The rAgy1 activity was enhanced by $FeSO_4$ (40%), KCl (34%), and NaCl (34%), compared with the control. The newly identified rAgy1 is a ${\beta}$-agarase, which acts to degrade agarose to neoagarotetraose (NA4) and neoagarohexaose (NA6) and may be useful for applications in the cosmetics, food, bioethanol, and reagent industries.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1237-1244
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• 2012

Agarase genes of non-marine agarolytic bacterium Cellvibrio sp. were cloned into Escherichia coli and one of the genes obtained using HindIII was sequenced. From nucleotide and putative amino acid sequences (713 aa, molecular mass; 78,771 Da) of the gene, designated as agarase AgaA, the gene was found to have closest homology to the Saccharophagus degradans (formerly, Microbulbifer degradans) 2-40 aga86 gene, belonging to glycoside hydrolase family 86 (GH86). The putative protein appears to be a non-secreted protein because of the absence of a signal sequence. The recombinant protein was purified with anion exchange and gel filtration columns after ammonium sulfate precipitation and the molecular mass (79 kDa) determined by SDS-PAGE and subsequent enzymography agreed with the estimated value, suggesting that the enzyme is monomeric. The optimal pH and temperature for enzymatic hydrolysis of agarose were 6.5 and $42.5^{\circ}C$, and the enzyme was stable under $40^{\circ}C$. LC-MS and NMR analyses revealed production of a neoagarobiose and a neoagarotetraose with a small amount of a neoagarohexaose during hydrolysis of agarose, indicating that the enzyme is a ${\beta}$-agarase.

• KSBB Journal
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• v.28 no.6
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• pp.349-355
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• 2013

SC092 strain, producing a polysaccharide degrading enzyme, was isolated from the seawater. This strain was identified as Microbulbifer sp. using the comparative sequence analysis against known 16S rRNA sequence. A polysaccharide degrading enzyme from this strain was used to acquire the enzymatic extracts of Sargassum fulvellum. DPPH radical scavenging and SOD activity of the enzyme extracts of S. fulvellum were about 61.9% and 82.9% at 2 mg/mL, respectively. Nitrite scavenging activities was 52.5% at 2 mg/mL on pH 1.2. In addition, ${\alpha}$-glucosidase inhibitory activity was also increased in a dose-dependent manner and was about 52.7% at 2 mg/mL. To determine the influence of enzyme extracts of S. fulvellum on alcohol metabolism, the generating activity of reduced-nicotinamide adenine dinucleotide (NADH) by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) were measured. ADH and ALDH activities were 118.0% and 177% at 2 mg/mL, respectively. ${\alpha}$-glucosidase inhibitory activity of enzyme extracts of S. fulvellum was remarkably increased in a dose-dependent manner and was about 52.7% at 2 mg/mL. These results indicate alcoholizing and ${\alpha}$-glucosidase inhibitory activities can be enhanced by the enzymatic extracts of S. fulvellum.