The integrated production of microbial lipids and bio-SiO2 from rice husks by an organic electrolytes pretreatment technology

• A full dissolution of rice husks was achieved in mixed organic electrolyte.
• Enzymatic hydrolysates were used as carbon resources for microbial lipid production.
• Nano-SiO2 materials were prepared by using residuals after the enzymatic hydrolysis.
• Mixed organic electrolyte showed better performance than that of pure ionic liquids.

In this study, a full dissolution behavior of rice husks (RHs) in ionic liquids-based organic electrolytes was achieved, and physicochemical effect of the dissolution pretreatment on the structures of RHs was elucidated. The physicochemical changes led to an enhanced subsequent enzymatic saccharification of RHs, and a total reducing sugars (TRSs) yield of 0.70 g g−1, and a glucose yield of 0.43 g g−1 were obtained. The hydrolysates could be used as carbon sources for the cultivation of Rhodosporidium toruloides Y4 for the production of microbial lipids with a satisfactory productivity of cell biomass (13.3 g L−1) and lipid content (32.5%) after 100 h cultivation. Further pyrolysis of the residuals after the enzymatic hydrolysis at 600 °C for 3 h resulted in new uniform, spherical silica powder materials with particle size around 150 nm, and surface area of 179.3 m2 g−1.

The dissolution pretreatment of rice husk (RH) results in an enhanced subsequent enzymatic saccharification of RH, with a total reducing sugars (TRSs) yield of 0.70 g g−1, and a glucose yield of 0.43 g g−1. The hydrolysates were used as carbon resources for cultivation of R. toruloides Y4 achieving a cell biomass yield and lipid content of 13.3 g L−1, and 32.5%, respectively. Silica material with uniform spherical structure and particle size around 150 nm and a surface area of 179.3 m2 g−1 was achieved through pyrolysis of the residuals after the enzymatic hydrolysis.Figure optionsDownload as PowerPoint slide