A novel approach for the production of bioactive metabolites

POSTEMSKY PABLO; MOYANO ANAHÍ ; VELA GUROVIC SOLEDAD; CUBITTO, M.A.

Rosario

Congreso; IV Reunión Internacional de Ciencias Farmacéuticas; 2016

Universidad Nacional de Rosario

The need of new antibiotics is a primary concern for the pharmaceutical industry since the development of resistant strains is constantly increasing. As well, the reisolation of known metabolites has led to the design of novel strategies for the activation of secondary metabolism and production of active substances. Understanding the natural environment of the antibiotic producers would lead to unexplored metabolic responses. In this work, we aim to test whether solid-state fermentation of actinomycetes in residual substrates discarded after the cultivation of mushrooms leads to the production of antibacterial substances. In that order, a suspension containing 106 spores/mL of Streptomyces SUE01 sp. was inoculated on sunflower seed hulls and sunflower seed hulls biotransformed by the mushroom Pleurotus ostreatus (oyster mushroom). To assess the relevance of abiotic and biotic factors, the substrates were subjected to two decontamination processes, namely pasteurization and autoclave sterilization. Microbial counts, microscopic observation and biological activities were evaluated after one week fermentation. Extracts of the colonized substrates (methanol 60%) were tested at 10 mg/mL against Bacillus subtilis by agar diffusion assay. Both the bacterial counts and the halos of inhibition of the extracts of Streptomyces grown in the pasteurized residual substrate were significantly different from the other treatments. Bacterial counts of heterotrophs reached 108 CFU/g in the pasteurized residual substrate after one week, while the co-culture with the actinomycete reduced this number by two logs. These results suggest that the interaction with other bacteria is a crucial factor for both the viability and production of bioactive metabolites by solid-state fermentation.