Antifungal and antitumor activities of cellulose-degrading myxobacteria isolated from soil in Vietnam

Myxobacteria are known to produce epothilone, a natural macrolide compound with significant antitumor activity achieved through the inhibition of microtubules formation during cell division, which is a mechanism critical to chemotherapy. This study investigated the antifungal and antitumor activities of myxobacteria isolated from soils enriched with decomposed plant material. Myxobacterial strains were isolated and screened by examining macroscopic characteristics, assessing cellulose degradation using filter paper as the sole carbon source, and observing the presence of fruiting bodies and motility on slides. Selected strains were cultured in CK6 medium containing Amberlite XAD-16 resin, and active compounds were eluted using methanol. Antifungal activity was evaluated using disk diffusion and thin-layer chromatography autography, and cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Among the 41 soil samples, three strains (QN01, QN02, and QN04) demonstrated cellulose degradation capability and exhibited morphological characteristics consistent with the Sorangium sp. The QN02 strain exhibited antifungal activity against pathogens, including Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Penicillium sp., and Mucor sp. Furthermore, extracts from QN02 inhibited MCF-7 breast cancer cells (IC50=159.1 ng/mL) and human embryonic kidney cells (HEK-293) human kidney cells (IC50=528.1 ng/mL). The QN02 strain is a promising source of antifungal and antitumor compounds.