Statistical optimization of anticandida metabolite production process using Streptomyces hydrogenans strain from mangrove soils

Abstract

Streptomyces hydrogenans is well known to exhibit antagonistic activity against several fungal pathogens. However, improving the potency of such inhibitory activity is challenging and necessitates the manipulation of fermentation conditions and nutritional requirements of the actinomycetes. The present study is focussed on statistical optimisation of the strain cultural process for achieving ample yield of novel anti-candida metabolites. Nine variables including soyabean meal, glucose, glycerol, calcium carbonate, sodium chloride, pH of the medium, strain inoculum level and incubation period were modeled by Plackett–Burman design for screening in order to predict their influence on the production of bioactive metabolites. Among them, the most critical variables that exert significant variation in the response of interest were identified to be incubation period, glucose and calcium carbonate (CaCO3). With a goal to achieve the maximum metabolite yield/ anti-candida potentiality/ or cost-cutting production, these significant factors were further optimized and validated employing a Box Behnken design. Design of experiment assisted fermentation process enhanced 1.8 fold productivity and antifungal activity at the optimal condition consisting soyabean meal (1.5%), glucose (1.030%), glycerol (0.25%), NaCl (0.5%), CaCO3 (0.1%), sea water (50%) as medium at pH 7.0, inoculums level (10%) and incubation period of 5 days.