Effects of carbon source and additives on biomass, exopolysaccharide production and morphology of Pleurotus ostreatus in submerged cultivation

Abstract

Aims: To investigate the influence of carbon sources and additives/surfactants on the mycelium growth and exopolysaccharides (EPS) production, including the morphology during submerged cultivation of Pleurotus ostreatus in the minimal-medium as the base medium. Methodology and results: Pleurotus ostreatus was cultivated in different types of carbon sources to investigate the effects of carbon sources to mycelium growth and changes of mycelium morphology which directly affects the synthesis of EPS. In addition, additives or surfactants can increase the bioavailability of less soluble substrates in the cultured medium for the mycelium growth and indirectly affects the EPS production. In this study, the cultivation of P. ostreatus in the minimal-medium by using glucose as the carbon source with the addition of lecithin at 1% (w/v) gave the highest EPS production 4.53 ± 0.30 g/L, an increase of about 89.53% when compared to the cultivation without the addition of lecithin. Addition of lecithin changes morphology of the pellets outer layer and under microscope showing a dense hyphal network surrounding the pellets with the sizes of micro pellets almost 0.5-1.5 mm which contributed to the increase of EPS production after 14 days cultivation at 26 °C. Conclusion, significance and impact of study: The choice of the carbon source should not only be for high productivity rate of mycelium growth and EPS production, but a cheaper alternative source should also be considered. In conclusion, high mycelium biomass and EPS production was achieved either by changes of the morphology through the type of carbon source and addition of additives such as lecithin.