Relationship between Crystallinity Index and Enzymatic Hydrolysis Performance of Celluloses Separated from Aquatic and Terrestrial Plant Materials

Abstract

Hydrolysis experiments of five cellulose samples (separated from two aquatic plants and three terrestrial plants, respectively) were conducted at various cellulase loadings (7 to 200 FPU/g cellulose). No obvious correlation was found between CrI and hydrolysis performance at low enzyme loadings (e.g. 7 and 28 FPU/g cellulose), as the hydrolysis was controlled by enzyme availability and the differences in cellulose structure were unimportant. At a sufficiently high enzyme loading (e.g. 200 FPU/g cellulose), the yield of reducing sugar was linearly proportional to the CrI value. Therefore, to establish such a correlation between cellulose structure and hydrolysis performance, hydrolysis experiments must be conducted under the conditions where enzyme availability is not a limiting factor. It was found that celluloses from sugarcane bagasse and water hyacinth have low CrI, achieve high sugar yields, exhibit fast reactions during enzymatic hydrolysis at low enzyme loadings, and can potentially be good feedstocks for bio-ethanol production.