Production of nigericin and niphimycin by soil isolate Streptomyces sp. MS1: Anti-Candida bioassay guided response surface methodology for the optimized culture medium

Abstract

Anti-Candida bioassay guided optimization of the culture medium was used in order to enhance the antifungal activity of the soil isolate MS1. Its morphological, physiological and biochemical characteristics, as well as 16S rDNA sequencing, assigned an MS1 isolate to genus Streptomyces. Optimization of the culture medium was achieved by experimental factorial design and response surface methodology. Maximal antifungal components production was obtained with starch, soybean meal and phosphates content of 40.52, 5.10 and 2.21 g/L, respectively. Chromatography and 1H and 13CNMR spectroscopy were employed for purification and structural characterization of antifungal antibiotics concurrently produced by this strain. These antibiotics were identified as polyether carboxylic antibiotic nigericin and guanidyl-polyol macrolide, niphimycin.nema