Zaporožskij Medicinskij Žurnal (Dec 2016)
Antifungal activity of streptomycetes isolated bentonite clay
Abstract
Aim. To investigate the biological activity of streptomycetes, isolated from Ukrainian bentonite clay. Methods. For identification of the investigated microorganisms there were used generally accepted methods for study of morpho-cultural and biochemical properties and sequencing of 16Ѕ rRNA producer. Antagonistic activity of the strain was determined by agar diffusion and agar block method using gram-positive, gram-negative microorganisms and fungi. Results. Research of autochthonous flora from bentonite clay of Ukrainian various deposits proved the existence of stable politaxonomic prokaryotic-eukaryotic consortia there. It was particularly interesting that the isolated microorganisms had demonstrated clearly expressed antagonistic properties against fungi. During bacteriological investigation this bacterial culture was identified like representative of the genus Streptomyces. Bentonite streptomycetes, named as Streptomyces SVP-71, inagar mediums (agar block method) inhibited the growth of fungi (yeast and mold); zones of growth retardation constituted of 11-36 mm, and did not affect the growth of bacteria. There were investigated the inhibitory effects of supernatant culture fluid, ethanol and butanol extracts of biomass streptomycetes on museum and clinical strains of fungi that are pathogenic for humans (Candida albicans, C. krusei, C. utilis, C. parapsilosis, C. tropicalis, C. kefir, S. glabrata, C. lusitaniae, Aspergillus niger, Mucor pusillus, Fusarium sporotrichioides). It has been shown that research antifungal factor had 100% of inhibitory effect against all fungi used in experiments in vitro. In parallel, it was found that alcohol extracts hadn’t influence to the growth of gram-positive and gram-negative bacteria absolutely. It was shown that the cultural fluid supernatant and alcoholic extracts of biomass had the same antagonistic effect, but with different manifestation. This evidenced about identity of antifungal substances synthesized into the broth and present in bacterial biomass. Conclusions. Secondary metabolites from antifungal properties are accumulated both in Streptomyces SVP-71 biomass and in the culture fluid. The obtained extracts can be used to create antifungal drugs.
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