Optimization Of Culture Conditions For Antimicrobial Activity Of Streptomyces Adustus

Abstract

Streptomyces spp., known for their prolific production of antimicrobial compounds, provides a wealth of resources for potential therapeutic uses against various pathogenic microbes. This study aimed to optimize the medium compositions (carbon and nitrogen sources) and cultural conditions (pH) for enhancing antimicrobial production from Streptomyces adustus, isolated in Con Dao Island, one of the promising strains for antimicrobial activities. After screening five tested media at three distinct intervals, tryptone soya broth (TSB) emerged as the most effective medium for antimicrobial substance production at 144 hours. Ethyl acetate was used to extract antimicrobial agents and for testing the extracts by the agar-well diffusion method. Subsequently, we optimized this medium by varying the concentrations of dextrose, tryptone, and pH within specified ranges (1-4g/L, 10-24g/L, and 5.0-9.0, respectively) using Box Behnken Design, in which the other ingredients were maintained at the original level. We evaluated the effect of dextrose as a carbon source, tryptone as a nitrogen source, and pH as a cultural condition through the 3D response surface plot. As a result, among several tested conditions, the optimal range against Staphylococcus aureus (1.8 g/L dextrose, 16.0 g/L tryptone, and pH 7.3) and Candida albicans (1.7 g/L dextrose, 17.5 g/L tryptone, and pH 8.0) was obtained. This study will be helpful in the implementation of antimicrobial production on a large-scale fermentation.