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

Abstract

Biomass pretreatment is a mandatory step for the biochemical conversion of lignocellulose to chemicals. During pretreatment, soluble compounds are released into the prehydrolyzate that inhibit the enzymatic hydrolysis step. In this work, we investigated how the reaction conditions in steam explosion pretreatment of beechwood (severity: 3.0–5.25; temperature: 160–230 °C) influence the resulting amounts of different inhibitors. Furthermore, we quantified the extent of enzyme inhibition during enzymatic hydrolysis of Avicel in the presence of the prehydrolyzates. The amounts of phenolics, HMF, acetic acid and formic acid increased with increasing pretreatment severities and maximal quantities of 21.6, 8.3, 43.7 and 10.9 mg/gbeechwood, respectively, were measured at the highest severity. In contrast, the furfural concentration peaked at a temperature of 200 °C and a severity of 4.75. The presence of the prehydrolyzates in enzymatic hydrolysis of Avicel lowered the glucose yields by 5–26%. Mainly, the amount of phenolics and xylose and xylooligomers contributed to the reduced yield. As the maximal amounts of these two inhibitors can be found at different conditions, a wide range of pretreatment severities led to severely inhibiting prehydrolyzates. This study may provide guidelines when choosing optimal pretreatment conditions for whole slurry enzymatic hydrolysis.

Assessment of the effectiveness of liquid hot water and steam explosion pretreatments of fast-growing poplar (Populus trichocarpa) wood

“…Some volatile substances were identified by the GC-MS analysis. The GC-MS analysis confirmed the presence of vanillin and syringaldehyde in the chloroform-ethanol extract, which are known products of lignin decomposition during biomass pretreatment (Jӧnsson and Martín 2016;Brethauer et al 2020). The results of GC-MS analysis are presented in Table 3 and discussed later in this paper.…”

“…In turn, the glucose content ranged from 3.7 to 23.2 mg/g native biomass and cellobiose from 2.1 to 9.8 mg/g native biomass. According to the results obtained by Brethauer et al (2020), the xylose also was a dominant sugar released to a liquid fraction. As a result of SE pretreatment, the maximal yield of 30 mg/g beech wood was reached at 180 °C.…”

Research on the Dynamic Response Properties of Nonlethal Projectiles for Injury Risk Assessment

“…Natural beechwood is a natural wood of medium hardness and softness, which has broad leaves and deciduous leaves and produces seeds, and its growth is prolonged, making soft hardwood. We chose the beech tree, a type of impact-resistant wood characterized by its lightweight and low cost . We took six cylindrical samples 20 × 20 cm from different pieces of this wood, using an automatic cutting machine with high accuracy (Figure S5).…”

“…We chose the beech tree, a type of impact-resistant wood characterized by its lightweight and low cost. 42 We took six cylindrical samples 20 × 20 cm from different pieces of this wood, using an automatic cutting machine with high accuracy ( Figure S5 ). Figure 2 b shows the samples selected before and after automatic slicing.…”

Techno-economic assessment of bioethanol production from lignocellulose by consortium-based consolidated bioprocessing at industrial scale

“…Feedstock properties, ethanol titer and yield were assumed to be the same as in the base case in order to calculate the net savings by using CBP. The pretreatment was changed to a pure steam pretreatment instead of a dilute acid-catalyzed steam pretreatment used in the base case, because previous studies have successfully shown that steampretreated lignocellulose can be converted by consortium-based CBP and the CBP parameters are based on the available experimentally derived data with steam gun pretreatment [17,29,30]. The necessary, specific membrane surface was set to 10 m 2 /m 3 reactor volume.…”