Bajić, Bojana Ž., Dodić, Jelena M., Grahovac, Jovana A., Jokić, Aleksandar I., Cvetković, Dragoljub D., Petrović, Lidija B., and Vučurović, Damjan G.
Numerous species of the genus Streptomyces, on the appropriate cultivation medium in the process of submerged biosynthesis, as a product of the secondary metabolism, and under aerobic conditions synthesize pharmacologically active compounds. The aim of presented study was optimization of different nitrogen sources in the cultivation medium for the production of antimycotics using a strain of Streptomyces spp. isolated from the environment. Experiments were carried out in accordance with Box-Behnken design with three factors at three levels (peptone: 3.0 g/l, 7.0 g/l and 11.0 g/l; yeast extract: 1.0 g/l, 3.0 g/l and 5.0 g/l; soybean meal: 5.0 g/l, 15.0 g/l and 25.0 g/l) and three repetitions in the central point. Cultivation mediums were analyzed for determination of residual sugar, residual nitrogen, pellet diameter and RNA. Also, antimycotic activity of the obtained cultivation mediums was determined using diffusion disc method on the Aspergillus spp. as the test microorganism. For the optimization of selected parameters, a Response Surface Methodology was used and the obtained data were analyzed using the software package DESIGN EXPERT 8.1. Achieved model with a coefficient of determination (R) of 0.952 predicted that the maximum inhibition zone diameter (24.0 mm) against microorganism Aspergillus spp. and the minimum amount of residual sugar (0.551528 g/l) under applied experimental conditions was produced when the contents of varied nitrogen sources were: peptone 11.0 g/l, yeast extract 4.32 g/l and soybean meal 25.00 g/l. [ABSTRACT FROM AUTHOR]