Optimization of Exopolysaccharide Production by Soil Actinobacterium Streptomyces plicatus under Submerged Culture Conditions

Abstract

Extracellular polymeric substances (EPSs) are ecologically friendly natural polymers produced by microorganisms in the surrounding media. Due to their varied chemical composition, exopolysaccharides are widely used in a variety of applications, including food, pharmaceuticals, and medical applications. In this work, thirty-six isolates of Actinobacteria isolated on starch nitrate medium from various locations of Egyptian soils were assessed for exopolysaccharide (EPS) synthesis. The isolated bacterium that produced the most EPS was Actinobacterium 10 (Streptomyces plicatus). Several culture and environmental parameters were investigated during the microbial growth in submerged culture to enhance bacterial growth and EPS production. The optimal crude EPS generation of 8.62 g/l was achieved after 7 days of incubation at 20 g/l starch concentration, at 35 °C and pH 7, under shaking at 120 rpm, with the most significant impacts. The findings of this study pave the door to produce large quantities of EPS from soil Actinobacteria for food and medicinal purposes.