• Microbiology and Biotechnology Letters
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• v.46 no.3
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• pp.234-243
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• 2018

The Antarctic Ocean contains numerous microorganisms that produce novel biocatalysts that can have applications in various industries. We screened various psychrophilic bacterial strains isolated from the Ross Sea and found that a Croceibacter atlanticus strain (Stock No. 40-F12) showed high lipolytic activity on a tributyrin plate. We isolated the corresponding lipase gene (lipCA) by shotgun cloning and expressed the LipCA enzyme in Escherichia coli cells. Homology modeling of LipCA was carried out using the Spain Arreo lake metagenome alpha/beta hydrolase as a template. According to the model, LipCA has an ${\alpha}/{\beta}$ hydrolase fold, Gly-X-Ser-X-Glymotif, and lid sequence, indicating that LipCA is a typical lipase enzyme. Active LipCA enzyme was purified fromthe cell-free extract by ammonium sulfate precipitation and gel filtration chromatography. We determined its enzymatic properties including optimum temperature and pH, stability, substrate specificity, and organic solvent stability. LipCA was immobilized by the cross-linked enzyme aggregate (CLEA) method and its enzymatic properties were compared to those of free LipCA. After cross-linking, temperature, pH, and organic solvent stability increased considerably, whereas substrate specificities did not changed. The LipCA CLEA was recovered by centrifugation and showed approximately 40% activity after 4th recovery. This is the first report of the expression, characterization, and immobilization of a C. atlanticus lipase, and this lipase could have potential industrial application.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.382-390
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• 2006

Various microorganisms were isolated from the surface waters and sediments of eutrophic lakes and reservoirs in Korea to enable an investigation of bacteria having algal lytic activities against Anabaena flos-aquae when water blooming occurs and to study enzyme profiles of algal lytic bacteria. Two bacterial strains, AFK-07 and AFK-13, were cultured, characterized and identified as Acinetobacter johnsonii and Sinorhizobium sp., respectively. The A. johnsonii AFK-07 exhibited a high level of degradatory activities against A. flos-aquae, and produced alginase, caseinase, lipase, fucodian hydrolase, and laminarinase. Moreover, many kinds of glycosidase, such as ${\beta}-galactosidase,\;{\beta}-glucosidase,\;{\beta}-glucosaminidase,\;and\; {\beta}-xylosidase$, which hydrolyzed ${\beta}-O-glycosidic$ bonds, were found in cell-free extracts of A. johnsonii AFK-07. Other glycosidases such as ${\alpha}-galactosidase,\;{\alpha}-N-Ac-galactosidase,\;{\alpha}-mannosidase,\; and\;{\alpha}-L-fucosidase$, which cleave ${\alpha}-O-glycosidic$ bonds, were not identified in AFK-07. In the Sinorhizobium sp. AFK-13, the enzymes alginase, amylase, proteinase (caseinase and gelatinase), carboxymethyl-cellulase (CMCase), laminarinase, and lipase were notable. No glycosidase was produced in the AFK-13 strain. Therefore, the enzyme system of A. johnsonii AFK-07 had a more complex mechanism in place to degrade the cyanobacteria cell walls than did the enzyme system of Sinorhizobium sp. AFK-13. The polysaccharides or the peptidoglycans of A. flos-aquae may be hydrolyzed and metabolized to a range of easily utilized monosaccharides or other low molecular weight organic substances by strain AFK-07 of. A. johnsonii, while the products of polysaccharide degradation or peptidoglycans were more likely to be utilized by Sinorhizobium sp. AFK-13. These bacterial interactions may offer an alternative effective approach to controlling the water choking effects of summer blooms affecting our lakes and reservoirs.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.6
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• pp.863-868
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• 2004

Lectin activities and chemical characteristics of Escherichia coli, Lactobacillus spp. and Bifidobacterium spp. originating from the porcine cecal mucosal layer were studied based on hemagglutination assay (HA) and hemagglutination inhibition assay (HIA). Although all the bacterial strains were able to agglutinate erythrocytes of porcine or rabbit origin, much higher HA titers were consistently observed for Lactobacillus spp. than for E. coli or for Bifidobacterium spp. A remarkable reduction in HA titers occurred by the treatment of E. coli and Lactobacillus spp. with protease or trypsin and of Bifidobacterium spp. with protease, trypsin or periodate. There were no significant effects on the HA titers of the three groups of bacteria after the treatment with lipase. Hemagglutination of E. coli was strongly inhibited by D (+)-mannose and D (+)-galactose; Lactobacillus spp. by $\alpha$-L-rhamnose and methyl-$\beta$-galactopyranoside; Bifidobacterium spp. by D (+)-alactose, $\alpha$-L-rhamnose, $\alpha$-L-fucose, L (+)-arabinose, D (+)-mannose, D (-)-fructose at a relatively low concentration (1.43 to 3.75 mg/ml). These results, combined with the enhanced HA activities of the three bacterial strains by modification of rabbit erythrocytes with neuraminidase and abolished HA activity of E. coli after treatment with $\beta$-galactosidase, indicate that it might be the glycoproteinous substances surrounding the surface of the bacterial cells that are responsible for the adhesions of these microorganisms by recognizing the specific receptors on the red blood cell.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.341-347
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• 2022

In this study, the bacterial community of galchi-baechu kimchi was determined using culture-based and culture-independent techniques (next generation sequencing:NGS), and showed discrepancies between results. Weissella koreensis and Pediococcus inopinatus were the dominant species according to the NGS results, while Bacillus species and P. inopinatus were dominant in the culture-dependent analysis. To identify safe starter candidates, sixty-five Bacillus strains isolated from galchi-baechu kimchi using culture-dependent methods were evaluated for their antibiotic resistance, presence of toxin genes, and hemolytic activity. Strains were then assessed for salt tolerance and protease and lipase activity. As a result, four strains-B. safensis GN5_10, B. subtilis GN5_19, B. velezensis GN5_25, and B. velezensis GT8-were selected as safe starter candidates for use in fermented foods.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.119-127
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• 2013

Twenty-three strains of Leuconostoc species and 45 strains of Weissella species inhibiting the growth of Lactobacillus sakei, one of the most populous lactic acid bacteria in over-ripened kimchi, were isolated from kimchi in our previous study. Among these hetero-fermentative 68 strains, Leuconostoc mesenteroides CK0128, Weissella cibaria CK0633, and W. cibaria KK0797 exhibited a relatively high survival rate in MRS medium, which was adjusted to pH 4.3 using an acid mixture consisting of acetic and lactic acids, and produced a large amount of exopolysaccharides. The culture supernatants of 3 strains were fractionated by a molecular weight cutter and lyophilized. The fractions with a molecular weight smaller than 3,000 Da showed antagonistic activity against Staphylococcus aureus and Lb. sakei. The anti-bacterial substances were very stable to heat treatments ($121^{\circ}C$, 15 min) and active at acidic conditions below pH 5. ${\alpha}$-Amylase, lipase, and proteolytic enzymes (proteinase K and pepsin) did not affect their activities. These non-proteinaceous anti-bacterial substances inhibited the growth of several food pathogens.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.39-47
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• 2014

Sponge in Lake Baikal is an unique organism. Microorganisms in sponges are assumed as precious resources for bioactive materials. For understanding the bacterial community in Baikalian sponges by cultivation, 92 strains of bacteria were isolated from lake water and 2 species of sponges, Baikalospongia sp. and Lubomirskia sp., Thirty five bacterial strains are isolated from ambient water near the sponge, 27 bacterial strains from Baikalospongia sp., 30 bacterial strains from Lubomirskia sp.. As a result, 78.3% and 57.6% of isolated bacterial strains has amylase and protease activity respectively, while strains with cellulose and lipase activities were 38.0% and 34.8%. By 16S rRNA sequence analysis of selected strains, 13 strains which were isolated from Baikalospongia sp. were belong to Pseudomonas spp.. Whereas, 14 strains which were isolated from Lubomirskia sp. were Pseudomonas spp., Buttiauxella agrestis, Pseudomonas fluorescens, Yersinia ruckeri, Bacillus spp., Paenibacillus spp., Bacillus thuringiensis, Bacillus simplex, Brevibacterium spp., Acinetobacter lwoffii. In culture media, Pseudomonas spp. dominance was supposed that according to allelophathy.

• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.125-134
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• 2017

Enhanced disease susceptibility1 (EDS1) is a regulator of basal defense responses required for resistance mediated by TIR-NBS-LRR containing R proteins. We identified three transcripts of EDS1-like genes encompassing diverse/separate expression patterns, based on the transcriptome analysis by Next Generation Sequencing (NGS) of V. flexuosa inoculated with Elsinoe ampelina. These genes were designated VfEDL1 (Vitis flexuosa Enhanced Disease Susceptibility1-like1), VfEDL2 and VfEDL3, and contained 2464, 1719 and 1599 bp, with 1791, 1227 and 1599 bp open reading frames (ORFs), encoding proteins of 596, 408 and 532 amino acids, respectively. The predicted amino acid sequences of all three genes showed the L-family lipase-like domain (class 3 lipase domain), and exhibited a potential lipase catalytic triad, aspartic acid, histidine and serine in the conserved G-X-S-X-G. All three VfEDL genes were upregulated at 1 hpi against the bacterial and fungal pathogens Rizhobiumvitis and E. ampelina, respectively, except VfEDL1, which was downregulated against E. ampelina at all time points. Against E. ampelina, VfEDL2 and VfEDL3 showed downregulated expression at later time points. When evaluated against R. vitis, VfEDL1 showed downregulated expression at all time points after 1 hpi, while VfEDL3 showed upregulation up to 24 hpi. Based on the expression response, all three genes may be involved in plant resistant responses against R. vitis, and VfEDL2 and VfEDL3 show additional resistant responses against E. ampelina infection.

• Journal of Life Science
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• v.24 no.6
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• pp.694-699
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• 2014

Indigenous microorganisms play decisive roles in biodegradation. In this study, eighty strains of hydrocarbon-degrading microbes were isolated from Incheon Bay. Among them, 12 strains were selected by an oil film collapsing method. The bacterial strain 'Incheon9' was eventually selected based on its relatively higher lipase and emulsification activities, and was identified as Acinetobacter sp. (NCBI accession code: KF54854). The optimum condition for the growth and emulsification activity of Acinetobacter sp. Incheon9 was $20^{\circ}C$, pH 7, and 1% NaCl. The optimum time for the best production of biosurfactant was 72 hrs. The oil degradation ability of Acinetobacter sp. Incheon9 was investigated by measuring the residual oils in the culture medium by gas chromatography (FID). This research provides foundational data for eco-friendly environmental remediation by microorganisms.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1577-1584
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• 2010

In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate ($S_2O_3$) oxidation, the production of ammonia ($NH_3$), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated salt-stressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.184-191
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• 2004

To investigate bacteria with algalytic activities against Anabaena cylindrica when water blooming occurs and to study enzyme profiles associated with alga-lytic activity, various bacterial strains were isolated from surface waters and sediments in eutrophic lakes or reservoirs in Korea. Among 178 isolates, only nine isolates exhibited lytic abilities against A cylindrica on the agar plates, and then the isolate AK-13 was selected as the strongest in lysing the cyanobacterium A. cytindrica. The strain AK-13 was characterized and identified as Sinorhizobium sp. based on fatty acid methyl ether profiles and 16S rDNA sequence. According to the results of the enzyme assays, in the strain An-13 of Sinorhizobium sp., alginase, amylase, proteinase (caseinase and gelatinase), carboxymethyl-cellulase (CMCase), laminarinase, and lipase was produced, namely CMCase, laminarinase and protease were highly active. None of glycosidase was produced. Therefore, enzyme systems of Sinorhizobium sp. AK-13 were very complex to degrade cell walls of A. cylindrica. The peptidoglycans of A. cylindrica mat be hydrolyzed and metabolized to a range of easily utilizable monosaccharides or other low molecular weight organic substances by Sinorhizobium sp. AK-13.