Recent advances in bioconversion of lignocellulosic biomass for volatile fatty acid production with rumen microorganisms

Lignocellulosic biomass is a possible alternative for fossil fuels due to its widespread availability and numerous benefits. Volatile fatty acids (VFAs) are important intermediates that can be converted into biofuels or chemicals. VFA production from lignocellulosic biomass via anaerobic fermentation is a promising approach for resource utilization. However, the high crystallinity and complex structure of lignocellulosic biomass limit its hydrolysis, thereby affecting VFA production. Rumen microorganisms (RMs) can efficiently break down cellulose and hemicellulose, offering distinct advantages during lignocellulose degradation. Recently, RMs have been used as an efficient inoculum for degrading lignocellulosic biomass to produce VFAs. Therefore, a review of VFA production from lignocellulosic biomass via anaerobic fermentation with RMs is necessary. To date, main factors affecting VFA production, novel reactor designs for VFA production, and main strategies enhancing VFA production have not been reviewed. In this review, the key RMs, hydrolases, and metabolic pathways involved in the conversion of lignocellulose into VFAs are analyzed. Recent advancements regarding the fermentation of lignocellulose to produce VFAs by RMs and the key factors involved are summarized. Moreover, enhancement strategies for VFA production and recovery methods for VFAs are explored. Finally, the current challenges and prospects for the fermentation of lignocellulosic biomass to produce VFAs by RMs are presented. This review offers insights and approaches for efficient VFA production from lignocellulosic biomass using RMs.