Multistage optimization of SSCF bioconversion of distilled spent grain for enhanced single-cell protein production

Sustainable production of single-cell protein (SCP) from distilled spent grain (DSG) offers an effective strategy to alleviate protein shortages while valorizing lignocellulosic waste. In this study, a novel integrated process was established by combining (i) dilute sulfuric acid-assisted high-temperature pretreatment with enzymatic hydrolysis, (ii) a synergistic β-glucanase and glucoamylase system that achieved 92.42 % total sugar release, and (iii) the application of a high-performance Cyberlindnera jadinii R2878 strain capable of co-metabolizing pentoses and hexoses. Furthermore, simultaneous saccharification and co-fermentation (SSCF) was coupled with spray drying to enhance downstream processing efficiency. This strategy yielded SCP with 47.5 % crude protein (CP), 14.2 % acid-soluble protein (ASP), and 0.94 g/L/h productivity. Pilot-scale validation (50 L) confirmed the robustness and scalability of the process. Collectively, this work highlights an innovative route that integrates advanced pretreatment, robust yeast metabolism, and SSCF-spray drying coupling, providing both technical novelty and practical feasibility for high-value recycling of DSG in green biomanufacturing.