Effect of Lignin Content on Cellulolytic Saccharification of Liquid Hot Water Pretreated Sugarcane Bagasse

Abstract

Lignin contributes to the rigid structure of the plant cell wall and is partially responsible for the recalcitrance of lignocellulosic materials to enzymatic digestion. Overcoming this recalcitrance is one the most critical issues in a sugar-flat form process. This study addresses the effect of low lignin sugarcane bagasse on enzymatic hydrolysis after liquid hot water pretreatment at 190 °C and 20 min (severity factor: 3.95). The hydrolysis of bagasse from a sugarcane line selected for a relatively low lignin content, gave an 89.7% yield of cellulose conversion to glucose at 40 FPU/g glucan versus a 68.3% yield from a comparably treated bagasse from the high lignin bred line. A lower enzyme loading of 5 FPU/g glucan (equivalent to 3.2 FPU/g total solids) resulted in 31.4% and 21.9% conversion yields, respectively, for low and high lignin samples, suggesting the significance of lignin content in the saccharification process. Further increases in the enzymatic conversion of cellulose to glucose were achieved when the bagasse sample was pre-incubated with a lignin blocking agent, e.g., bovine serum albumin (50 mg BSA/g glucan) at 50 °C for 1 h prior to an actual saccharification. In this work, we have demonstrated that even relatively small differences in lignin content can result in considerably increased sugar production, which supports the dissimilarity of bagasse lignin content and its effects on cellulose digestibility. The increased glucose yields with the addition of BSA helped to decrease the inhibition of non-productive absorption of cellulose enzymes onto lignin and solid residual lignin fractions.

Steam Explosion Pretreatment of Beechwood. Part 2: Quantification of Cellulase Inhibitors and Their Effect on Avicel Hydrolysis

“…For LHW pretreatment of oil palm mesocarp fiber, the amount of generated phenolics ranged from 12 to 45 mg/g biomass for pretreatments at 150-220 • C and at severities of 3.25-4.83, thereby exceeding the values found in this study [35]. Even higher values of 55 and 66 mg/g biomass were recently reported for a low and a high lignin variant of LHW pretreated sugar cane bagasse (190 • C, 20 min, log R 0 = 3.95) [36].…”

Liquid Hot Water Pretreatment and Enzymatic Hydrolysis as a Valorization Route of Italian Green Pepper Waste to Delivery Free Sugars

“…According to these results, a major proportion of lignin in the pretreated material seemed to be observed since lignin offered a characteristic peak at about 1514 cm −1 , corresponding to the aromatic skeletal vibration, and a higher number of small peaks between 1750 and 1000 cm −1 approximately [73]. This observation could indicate that no depolymerization of lignin during the pretreatment occurred, as already suggested by Ázar et al [77].…”

Commercial Washing Detergents-Assisted Alkaline Pretreatment for Lignocellulosic Sugars Production: A First Report

“…Detergent O after pH adjustment of 12 caused maximum lignin removal (Table 2), which in turn showed the higher sugar recovery (50-67%) after enzymatic hydrolysis. Ladeira et al (2020) found 22% lignin in the liquid hot water-pretreated SCB showing 52% of glucose yield after enzymatic hydrolysis. Seo et al (2017) observed 67% lignin removal from lignocellulose after a mixed pretreatment with acids and surfactants.…”