• Journal of Microbiology and Biotechnology
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• v.28 no.10
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• pp.1706-1715
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• 2018

Several non-methylotrophic bacteria have been reported to improve the growth and activity of methanotrophs; however, their interactions remain to be elucidated. We investigated the interaction between Methylocystis sp. M6 and Microbacterium sp. NM2. A batch co-culture experiment showed that NM2 markedly increased the biomass and methane removal of M6. qPCR analysis revealed that NM2 enhanced both the growth and methane-monooxygenase gene expression of M6. A fed-batch experiment showed that co-culture was more efficient in removing methane than M6 alone (28.4 vs. $18.8{\mu}mol{\cdot}l^{-1}{\cdot}d^{-1}$), although the biomass levels were similar. A starvation experiment for 21 days showed that M6 population remained stable while NM2 population decreased by 66% in co-culture, but the results were opposite in pure cultures, indicating that M6 may cross-feed growth substrates from NM2. These results indicate that M6 apparently had no negative effect on NM2 when M6 actively proliferated with methane. Interestingly, a batch experiment involving a dialysis membrane indicates that physical proximity between NM2 and M6 is required for such biomass and methane removal enhancement. Collectively, the observed interaction is beneficial to the methanotroph but adversely affects the non-methylotroph; moreover, it requires physical proximity, suggesting a tight association between methanotrophs and non-methylotrophs in natural environments.

• 한국약용작물학회:학술대회논문집
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• 2012.05a
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• pp.181-182
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• 2012

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.125.1-125
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• 2002

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.04a
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• pp.116-116
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• 1979

In the experiment of cholesterols and steroidal compounds. gas chromatography has been widely used to determine the compounds. Without the facility, we could determine the amount of 17-ketosteroids in the use of t. 1. c technique. In the muicrobial conversion of cholesterol to 17-ketsoteroids, $\alpha,$ $\alpha'-dipyridyl$ which might be a inhibitor of $9\alpha-hydroxylase$ of steroid skeleton was added to microbial culture broth. The inhibitor contaminated due to its solubility in organic solvents and hindered the determination of 17-ketost eroids on t.1. c in all the process of the experiment. we successfully determined the 17-ketosteroids by the use of Ag$^{+}$ band on t. 1. c. plate.e.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.125.2-125
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• 2002

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1175-1182
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• 2021

We investigated the effect of bovine lactoferricin (Lfcin-B), a peptide derived from bovine lactoferrin, on activation of intestinal epithelial cells in IEC-6 intestinal cell, and protection against in vivo rotavirus (RV) infection. Treatment with Lfcin-B significantly enhanced the growth of IEC-6 cells and increased their capacity for attachment and spreading in culture plates. Also, Lfcin-B synergistically augmented the binding of IEC-6 cells to laminin, a component of the extracellular matrix (ECM). In the analysis of the intracellular mechanism related to Lfcin-B-induced activation of IEC-6 cells, this peptide upregulated tyrosine-dependent phosphorylation of focal adhesion kinase (FAK) and paxillin, which are intracellular proteins associated with cell adhesion, spreading, and signal transduction during cell activation. An experiment using synthetic peptides with various sequences of amino acids revealed that a sequence of 9 amino acids (FKCRRWQWR) corresponding to 17-25 of the N-terminus of Lfcin-B is responsible for the epithelial cell activation. In an in vivo experiment, treatment with Lfcin-B one day before RV infection effectively prevented RV-induced diarrhea and significantly reduced RV titers in the bowels of infected mice. These results suggest that Lfcin-B plays meaningful roles in the maintenance and repair of intestinal mucosal tissues, as well as in protecting against intestinal infection by RV. Collectively, Lfcin-B is a promising candidate with potential applications in drugs or functional foods beneficial for intestinal health and mucosal immunity.

• Archives of Pharmacal Research
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• v.19 no.4
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• pp.261-263
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• 1996

SK-302B, an antibiotic purified from soil Streptomyces sp. 302, was structurally identified as echinomycin (C/sub 50/H/sub 66/N/sub 11/S/sub 2/). In the present experiment, the possibility of SK-302B as an anticolon cancer agent was investigated by using chemosensitivity system (MTT assay, clonogenic assay). Treatment of SK-302B on various colon cancer cell lines resulted in a significant cytotoxicity and tumor colony formation inhibition. These studies showed that SK-302B had a potent inhibition on colon cancer cells.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.680-686
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• 2003

This study was carried out to characterize the antilisterial substances produced by Leuconostoc sp. W65 and to evaluate the effects of pH, temperature, and time on inhibitory activity using response surface methodology. Leucocin W65, an antilisterial substance produced by Leuconostoc sp. W65, markedly inhibited the growth of Listeria monocytogenes, L. innocua, and L. ivanovii, whereas other pathogens including Gram-negative bacteria were not susceptible. The pH was the most effective factor with regard to bacteriocin activity, while temperature and time of heat treatment had no significant effect. Fifty percent of inhibitory activity remained after 22.8 min at pH 4.2 and $121^{\circ}C$. Leucocin W65 was purified by ammonium sulfate precipitation, hydrophobic interaction chromatography, and tricine-SDS-PAGE. Compositional analysis originally estimated the peptide to be 56 amino acids in length without asparagine, glutamine, and tryptophane. The sequence of partial N-terminal amino acid residues of purified bacteriocin was identified as follows: $NH_{2}-XGXAGVXPXGGQQPXVPLXYP$.

• Journal of Microbiology and Biotechnology
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• v.3 no.1
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• pp.6-11
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• 1993

An autonomously replicating sequence (Kf-ARS1) of Kluyveromyces fragilis was cloned from the genomic library which was constructed using pHN134 as a cloning vector to make a new host-vector system for the production of heterologous protein from K. fragilis as a host. The cloning vector pHN134 was composed of $Km^r, Ap^r$ and multiple cloning site in LacZ . A clone carrying Kf-ARS1 was isolated and the recombinant plasmid was designated as pIKD102. The cloned fragment was 2.3 kb (EcoRI/EcoRI) in length. Subcloning experiment showed that the region for ARS activity was 1.5 kb (SalI/EcoRI) fragment. It was shown that the Kf-ARS1 was active in Saccharomyces cerevisiae and Kluyveromyces fragilis.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.237-242
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• 1992

In order to clone the gene coding for alkaline phosphatase in the yeast Kluyveromyces fragilis, a genomic library was constructed using the yeast-E. coli shuttle vector pHN114 as a cloning vector. From the genomic library, a clone carrying the gene was isolated and the plasmid was designated as pSKH101. A restriction enzyme map was made using this plasmid. Subcloning experiments and complementation studies showed that alkaline phosphatase was active only in the original 3.1 kb insert. Southern hybridization analysis confirmed that the cloned DNA fragment was derived from K. fragilis genomic DNA. Using a minicell experiment, the product of the cloned gene was identified as a protein with a molecular weight of 63 KDa. A 0.6 kb HindIII fragment, which showed promoter activity, was isolated using the E. coli promoter-probe vector pKO-1.