Valorization of untreated rice bran towards bioflocculant using a lignocellulose-degrading strain and its use in microalgal biomass harvest

摘要

BackgroundMicroalgae are currently considered as a promising feedstock for the production of biofuels and high-value products. However, the efficient harvest of microalgal biomasses from their culture broth is a major challenge. The harvesting of algal biomass by flocculation combined with gravity sedimentation is more convenient and cost-effective than traditional methods such as centrifugation and filtration. Compared to inorganic and chemically synthetic flocculants, bioflocculants are a suitable choice for microalgal harvest due to their biodegradable and nontoxic properties. Nonetheless, the high production costs associated with expensive substrates hinder the commercial applications of bioflocculants. Previous studies have shown that the hydrolysates of lignocellulosic biomasses from dilute acid hydrolysis can be utilized as an inexpensive carbon source for the production of bioflocculants. However, the toxic by-products generated in the dilute acid hydrolysis step limit the efficiency of subsequent fermentation. The strains that produce bioflocculants by using untreated lignocellulosic materials can circumvent the pretreatment process, as well as promote the application of bioflocculants in microalgal harvest.