Biosynthesis of Polyene Antibiotics and Phytohormones by Streptomyces netropsis IMV Ac-5025 under the Action of Exogenous Isopentenyladenosine

Abstract

Streptomyces are active producers of a wide range of metabolites with multidirectional biological activity. Streptomyces netropsis IMV Ac-5025 synthesizes a polyene antibiotic complex in which two fractions were identified: heptaene candidine and a new tetraene fraction of unknown structure. The influence of secondary metabolites on the polyene antibiotics biosynthesis by soil streptomycetes is insufficiently explored. The aim of this work was to research the effect of exogenous isopentenyladenosine on the biosynthesis of polyene antibiotics and cytokinins by S. netropsis IMV Ac-5025. Methods. The strain was cultured in submerged cultivation condition in organic (soy) and synthetic (starch-ammonia) liquid nutrient media. The studies of biomass accumulation (gravimetric method), glucose consumption (glucose oxidase method), pH changes of culture media (ionometric method), biosynthesis of polyene antibiotics, and phytohormones (quantitative and qualitative thin layer chromatography spectrodensitometric method) were conducted. The results were analyzed in Statisticav.6.0 program. Results. It was found that polyene antibiotics are synthesized after the first day of cultivation, which indicates their role in the metabolism of streptomycetes. The biggest amount of the polyene antibiotics was accumulated in the stationary phase of producer growth (on the 7th day). It was found the decrease of polyene antibiotics and cytokinins accumulation in the producer’s biomass with the increase of exogenous cytokinin concentration from 25 ng/mL to 500 ng/mL. The bioproduction of the tetraene fraction was suppressed to a greater extent – up to 92% in the synthetic and up to 23% – in organic nutrient media. However, the amount of producer biomass increased under the action of the exogenous substance that confirming the positive effect of exogenous cytokinin on cell division of S. netropsis IMV Ac-5025. Exogenous isopentenyladenosine reduced the accumulation of endogenous cytokinins in streptomycetes biomass. Conclusions. The obtained results indicate an indirect metabolic relationship between the biosynthesis of polyene antibiotics and cytokinins in soil streptomycetes and provide a basis for the regulation of the biotechnological process for bioproduct formation with the appropriate quantitative composition of its components.