Enzymatic Conversion of Different Qualities of Refined Softwood Hemicellulose Recovered from Spent Sulfite Liquor

Abstract

Spent sulfite liquor (SSL) from softwood processing is rich in hemicellulose (acetyl galactoglucomannan, AcGGM), lignin, and lignin-derived compounds. We investigated the effect of sequential AcGGM purification on the enzymatic bioconversion of AcGGM. SSL was processed through three consecutive purification steps (membrane filtration, precipitation, and adsorption) to obtain AcGGM with increasing purity. Significant reduction (~99%) in lignin content and modest loss (~18%) of polysaccharides was observed during purification from the least pure preparation (UFR), obtained by membrane filtration, compared to the purest preparation (AD), obtained by adsorption. AcGGM (~14.5 kDa) was the major polysaccharide in the preparations; its enzymatic hydrolysis was assessed by reducing sugar and high-performance anion-exchange chromatography analysis. The hydrolysis of the UFR preparation with Viscozyme L or Trichoderma reesei β-mannanase TrMan5A (1 mg/mL) resulted in less than ~50% bioconversion of AcGGM. The AcGGM in the AD preparation was hydrolyzed to a higher degree (~67% with TrMan5A and 80% with Viscozyme L) and showed the highest conversion rate. This indicates that SSL contains enzyme-inhibitory compounds (e.g., lignin and lignin-derived compounds such as lignosulfonates) which were successfully removed.

Cross-Feeding and Enzymatic Catabolism for Mannan-Oligosaccharide Utilization by the Butyrate-Producing Gut Bacterium Roseburia hominis A2-183

“…Determination of Carbohydrate Utilization and Short-Chain Fatty Acids (SCFAs) Production 2.6.1. Utilization of Glucose and MOS/GMOS The utilization of glucose and MOS/GMOS was determined during the growth of R. hominis and B. adolescentis as mono-and cocultures on these carbohydrate sources by analyzing the cell-free supernatant (see Section 2.3), using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), as described before [16,40] in Section 2.11…”

“…Analysis of mono-and oligosaccharides was performed by using HPAEC-PAD, using CarboPac PA20 (060142, Dionex CarboPac PA20 BioLC, 3 × 150 mm, ThermoFisher Scientific, Sunnyvale, CA, USA) and PA200 (062896, Dionex CarboPac Pa200 BioLC, 3 × 250 mm, ThermoFisher Scientific, Sunnyvale, CA, USA) analytical columns coupled to guard columns of the same material on a Dionex ICS-5000 system (ThermoFisher Scientific, Sunnyvale, CA, USA) according to previously described methods [16,40]. Standards of appropriate monosaccharides, including mannose (M1) or galactose (G1) (Sigma Aldrich, St Louis, MO, USA); linear mannan-oligosaccharides (MOS), including mannobiose (M2), mannotriose (M3), mannotetraose (M4), and mannopentaose (M5); and galactosylated mannan-oligosaccharides (GMOS), including galactosyl mannotriose (GM3) and di-galactosyl mannopentaose (G2M5), were used (Megazyme, Bray, Ireland) (2.5-50 µM mannose (M1) or galactose (G1) for PA20, 2.5-30 µM M1-M5 and GMOS for PA200).…”

“…For the analysis of bacterial saccharide utilization, the elution was performed according to the previously described method optimized for fermentation media, using PA200 [16]. The analysis of monosaccharides (PA20) in enzyme incubations was according to [40], and for oligosaccharides, the PA 200 method described by Morrill et al [48] was used, but with a slightly reduced time (10 instead of 15 min) for the sodium acetate gradient (0-50 mM), applied in 78 mM NaOH. An additional wash step (3 min, 200 mM NaOH) was added.…”

Wood hemicelluloses as effective wall materials for spray-dried microcapsulation of polyunsaturated fatty acid-rich oils

“…During cellulose refinement, hemicelluloses are treated as lowvalue by-products remaining outside of the biorefinery process during which hemicelluloses, along with lignin, typically end up in waste streams and are primarily utilized for heat and energy (Mikkonen, 2020). However, hemicelluloses have been efficiently recovered from the process water of thermomechanical pulping (Thuvander et al, 2019;Bhattacharya et al, 2022), and from sawdust and wood chips using pressurized hot water extraction (PHWE) (Kilpeläinen et al 2014), heat fractionation (Chadni et al 2019a), steam explosion (Chadni et al 2019b), and high voltage electrical discharge (Chadni et al 2019c). The recovered hemicelluloses have been investigated as gels (Alakalhunmaa et al, 2016), films (Mikkonen et al, 2015), and hydrocolloids to stabilize emulsions (Mikkonen, 2020).…”

Monitoring Membrane Fouling Using Fluid Dynamic Gauging: Influence of Feed Characteristics and Operating Conditions

“…Their subsequent separation can be accomplished using membrane processes [2]; however, these wood constituents can potentially foul the membrane systems employed in the fractionation and concentration of the desired components. Studies on pressure-driven membrane filtration have been conducted using process waters from thermomechanical pulp mills [3][4][5], Kraft black liquor [6][7][8], and spent sulfite liquor [9][10][11]. These studies highlight the complex interactions of wood components, necessitating advanced techniques for monitoring their fouling behavior rather than relying solely on changes in permeate flux and transmembrane pressure (TMP).…”