• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.345-349
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• 1998

Fifty isolates of myxobacteria were isolated from soils from several areas in Korea during 1996-1997 and bioactivity against plant pathogenic fungi of these isolates was examined. A myxobacterial isolate KR025 showed good antifungal activities against Pyricularia oryzae, Cryphonectria parasitica, Colletotrichum lagenarium, and C. gloeosporioides but did not against Rhizoctonia solani, Fusarium oxysporum and Pythium ultimum. The bacterium was identified as Myxococcus fulvus based on morphological and physiological characteristics. Antifungal substances were extracted from culture broth and bacterial cell of Myxococcus fulvus KR025 by ethyl acetate. Antifungal substance of Myxothiazole (100 ${\mu}{\textrm}{m}$/ml) produced by Myxococcus fulvus KR 025 controlled 97.0% rice blast, tomato late blight, wheat leaf rust, and barley powdery mildew and showed 45.0 and 82.6% disease control of rice sheath blight and cucumber gray model, respectively.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.765-775
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• 2018

Using MCF7 breast cancer cells, we tested the anticancer activity of metabolites from 130 strains of myxobacteria newly isolated in South Korea. Of these, three strains whose metabolites had high anticancer activity and low cell toxicity were selected and identified by their fruiting body morphology, cell morphology, and 16S rRNA sequence. Strains KYC4030 and KYC4048 were determined to be Myxococcus fulvus, whereas strain KYC4081 was identified as Corallococcus coralloides. We found that metabolites of M. fulvus KYC4048 demonstrated no toxicity in normal cells but specifically induced cancer cell death by suppressing the expression of WNT2B. This discovery highlights the value of assessing the metabolic and biomedical potential of myxobacteria, even those that are already known but were isolated from new areas, and the possible use of metabolites from M. fulvus KYC4048 in cancer treatment.

• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.540-549
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• 2021

The Wnt/β-catenin signaling pathway is involved in breast cancer and Myxococcus fulvus KYC4048 is a myxobacterial strain that can produce a variety of bioactive secondary metabolites. Although a previous study revealed that KYC4048 metabolites exhibit anti-proliferative effects on breast cancer, the biochemical mechanism involved in their effects remains unclear. In the present study, KYC4048 metabolites were separated into polar and non-polar (ethyl acetate and n-hexane) fractions via liquid-liquid extraction. The effects of these polar and non-polar KYC4048 metabolites on the viability of breast cancer cells were then determined by MTT assay. Expression levels of Wnt/β-catenin pathway proteins were determined by Western blot analysis. Cell cycle and apoptosis were measured via fluorescence-activated cell sorting (FACS). The results revealed that non-polar KYC4048 metabolites induced cell death of breast cancer cells and decreased expression levels of WNT2B, β-catenin, and Wnt target genes (c-Myc and cyclin D1). Moreover, the n-hexane fraction of non-polar KYC4048 metabolites was found most effective in inducing apoptosis, necrosis, and cell cycle arrest, leading us to conclude that it can induce apoptosis of breast cancer cells through the Wnt/β-catenin pathway. These findings provide evidence that the n-hexane fraction of non-polar KYC4048 metabolites can be developed as a potential therapeutic agent for breast cancer via inhibition of the Wnt/β-catenin pathway.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.183-188
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• 2009

Seven isolates showing strong proteolytic activity, KYC 1028, 1100, 1134, 1139, 1151, 1159, and 1182, were collected. Out of them, the broth of KYC 1134 and KYC 1139 showed the high proteolytic activity measured by azocazein. To determine 16S rDNA sequences for identification, 16S rDNA of seven isolates were amplified and compared with the 16S rDNA sequences of other myxobacteria at NCBI. It is evident from the phylo-genetic tree that the isolates belong to the genus Myxococcus. Sharing high percentage similarity values with myxobacteria, the 16S rDNA sequences were involved in two species, Myxococcus macrospores and M. Fulvus. Biochemical characteristics of KYC 1134 broth, which showed the highest proteolytic activity, showed increased activity 8 times to seven days after culture, and protein production were increased gradually and stopped at five days. The broth had optimal temperature at $60^{\circ}C$ for proteolytic activity, and stability of pH was ranged from pH 5 to 10, at $50^{\circ}C$ and 60, respectively. To classify proteases being in the broth, ten inhibitors were determined and only bestatin showed 27% inhibition effect. The inhibition result demonstrates that the broth contains kinds of amino peptidases and other exopeptidases.