Production of bioemulsifying compounds from Phoma dimorpha using agroindustrial residues as additional carbon sources

Abstract

Bioemulsifying compounds are intracellular (IPS) and extracellular (EPS) biopolymers produced naturally by microorganisms during their growth and have been the interest of many researchers due to their biodegradability and potential to replace conventional emulsifiers. Large-scale production of bioemulsifying compounds is still limited because of the high processing cost. Therefore, this study focuses on the production of such compounds using the fungus Phoma dimorpha supplemented with low-cost substrates. Agroindustrial residues were used as the additional carbon source in submerged fermentation, such as glycerol from the biodiesel industry, brewer's spent grain, and rice bran. The effects of these carbon sources were evaluated on the production of IPS and EPS, biomass concentration, pH, density, surface tension, emulsification index, and bioherbicidal activity. In general, the best results were found for the fermented broth obtained when 5% (w/v) of crude glycerol was supplemented. The main results in this condition were the highest EPS yield of 5.48 g/L, IPS yield of 0.072 g/L, biomass concentration of 12.8 g/L, the highest emulsification index of 70%, and the lowest surface tension of 51.85 mN/m. The supplementation with glycerol increased the concentration of EPS in the medium and the emulsification index without affecting IPS production and biomass concentration. It also showed faster action against bioindicators and more satisfactory results for bioherbicidal activity. • Bioemulsifying compounds were obtained from the fungus Phoma dimorpha . • Agroindustrial residues were investigated as an additional carbon source. • Extracellular polysaccharides-enriched fractions increased the herbicidal activity.