Sucralose-Derived Solid Acid Catalysts Highly Selective Production of Cellulosic Hydrolysate: Source for Microbial Lipid Synthesis

Lignocellulose, the most abundant biomass resource, was a promising alternative to oil resources. The acid catalyst can hydrolyze lignocellulose to reduce sugars, the raw material for lipid production via fermentation. However, the by-product yield during hydrolysis would inhibit yeast activity when directly applying lignocellulose hydrolysate from dilute acid-catalyzed to microbial lipid production. In this paper, a solid acid catalyst highly selective for lignocellulose (rice straw) hydrolysis was prepared to minimize the effects of by-products. Also, a combination of solid acid catalysts to generate glucose with subsequent microbial fermentation was studied to obtain the higher efficiency of lipid production.A carbon-based solid acid catalyst with an enhanced hydrolysis capacity of cellulose and lignocellulose was efficiently prepared. It resulted in 71% yield of glucose with 97% of selectivity with optimal catalyst in hydrolyzing milled cellulose. The optimal preparation conditions of the catalyst were: carbonization temperature 642 K, sulfonation temperature 412 K, initial sulfonation time 12.5 h, and liquid-to-solid ratio 11.5. To expand the catalyst’ application, the rice straw hydrolysate catalyzed by the prepared catalyst was then applied to the microbial lipid production for the first time. Both dilute sulfuric acid and Amberlyst-15 resin as hydrolysis catalysts caused a decrease in yeast biomass, lipid content, and lipid yield. However, when the hydrolysate was obtained from co-heating rice straw with sucralose-derived solid acid catalyst, the yeast biomass, lipid content, and lipid yield in the presence of 5-HMF (0.39 g/L) were 12.6 g/L, 48.1%, and 7.6 g/L, respectively, and were almost similar to the control group. Our results showed that a combination of solid acid catalysts with subsequent microbial fermentation to generate lipid was confirmed to be environmentally friendly and low cost.Graphical Abstract