Bioprocess development employing design of experiments for antibiotic production from Streptomyces parvulus strain sankarensis-A10

Abstract

Optimization of antibiotic production medium and fermentation conditions of Streptomyces parvulus strain sankarensis-A10 was studied using classical and statistical methods. After selection of the basal production medium, the effect of sea water and incubation time on antibiotic production was investigated by classical method. In the first step of optimization, factors that significantly affect antibiotic production such as starch, K2HPO4, FeSO4.7H2O, KNO3 and pH were selected based on Plackett-Burman design. In the second step, three significant factors, starch, KNO3, pH, with a positive effect were optimized with a 33 factorial Box-Behnken design and analysed using response surface analysis. The optimal values for maximum antibiotic production were as follows, starch- 20 g/l, pH- 8.0 and KNO3- 3 g/l. Under optimal conditions, the antibacterial activity was found to be 620 U/ml and 616.66 U/ml against Staphylococcus aureus and Escherichia coli, respectively, which indicated that the activity was 1.4 folds higher in contrast to antibacterial activity prior to optimization. TLC-based partial purification of crude extract and bioassay of the fractions revealed the presence of four active compounds with Rf values of 0.275, 0.2, 0.125 and 0.062. These could probably be novel bioactive compound(s) in the crude extract, which could prove to be a novel source of antibiotics.