Self-Buffering Effect of Solids During High-Solid Enzymatic Hydrolysis of Lignocellulose

The role of buffer in modulating the enzymatic hydrolysis environment of lignocellulose is crucial. However, studies on the impact of buffer on high-solid enzymatic hydrolysis remain limited. This study discovered that utilizing deionized water as a reaction medium, rather than the conventional buffer, did not influence the enzymatic hydrolysis of steam-exploded corn stover when the solid loading ranged between 15 and 25%. At 15% solid loading, the glucan conversion in the group treated with buffer was recorded at 89.8%, with a corresponding glucose concentration of 51.1 g/L. In contrast, the group without buffer exhibited a conversion of 88.9% and a glucose concentration of 50.5 g/L. The increase of acid groups in lignin was attributed to the formation of phenolic hydroxyls during steam explosion, which provided the substrate with the necessary conditions for buffering effects. Sequentially, during the high-solid enzymatic hydrolysis process, the substrate’s increased pore volume and specific surface area could potentially offset the buffering capacity, which led to the buffering effect becoming ineffective. Leveraging the self-buffering effect of the substrate, a fed-batch strategy was developed. This strategy replaced the water supplementation with buffers, augmenting the solid loading from 20 to 33% across six distinct feeding sessions over a span of 72 h. This not only reduced costs but also laid the foundation for the industrial viability of lignocellulosic high-concentration sugar production, thereby advancing the biofuels and bioproducts sector. These findings provide valuable insights for the exploration of solid reaction processes.