Hot Compressed Water Pretreatment and Surfactant Effect on Enzymatic Hydrolysis Using Agave Bagasse

Abstract

Agave bagasse is a residual biomass in the production of the alcoholic beverage tequila, and therefore, it is a promising raw material in the development of biorefineries using hot compressed water pretreatment (hydrothermal processing). Surfactants application has been frequently reported as an alternative to enhance monomeric sugars production efficiency and as a possibility to reduce the enzyme loading required. Nevertheless, the surfactant’s action mechanisms in the enzymatic hydrolysis is still not elucidated. In this work, hot compressed water pretreatment was applied on agave bagasse for biomass fractionation at 194 °C in isothermal regime for 30 min, and the effect of non-ionic surfactants (Tween 20, Tween 80, Span 80, and Polyethylene glycol (PEG 400)) was studied as a potential enhancer of enzymatic saccharification of hydrothermally pretreated solids of agave bagasse (AGB). It was found that non-ionic surfactants show an improvement in the conversion yield of cellulose to glucose (100%) and production of glucose (79.76 g/L) at 15 FPU/g glucan, the highest enhancement obtained being 7% regarding the control (no surfactant addition), using PEG 400 as an additive. The use of surfactants allows improving the production of fermentable sugars for the development of second-generation biorefineries.

Sustainable Valorisation and Efficient Downstream Processing of Giant Reed by High‐Pressure Carbon Dioxide Pretreatment

“…surface. [28] In the present investigation, water-soluble PEG 400 was selected as a non-ionic surfactant according to previous studies [29,43] and for the first time it was employed in combination with scCO 2 and FeCl 3 -catalysed scCO 2 . Moreover, in the perspective of the valorisation of sugar-rich hydrolysates obtained from the scCO 2 -catalysed hemicellulose hydrolysis via fermentation route, PEG 400 boosts the metabolic performance and the vitality of biocatalysts.…”

“…Hydrophobic interactions are the most influential on non-specific binding of cellulases onto lignin and humins surface. [29] Surfactants like PEG 400 are amphiphilic molecules that contain both hydrophilic and lipophilic groups that can reduce surface tension and help to remove hydrophobic molecules and modify the structure and surface of lignocellulosic biomass. [30] The role of PEG 400 can be explained by the modification of the structure of the biomass allowing greater accessibility to Cellic ® CTec3 HS enzymes, and by the reduction of the non-productive adsorption of the cellulase enzyme on lignin due to the preferential adsorption of the surfactant onto the exposed surface of lignin.…”

“…In fact, lignin is a hydrophobic aromatic polymer that shows a significant affinity for cellulase enzymes by hydrophobic, electrostatic, or hydrogen‐bonding interactions, which reduce their activity. Hydrophobic interactions are the most influential on non‐specific binding of cellulases onto lignin and humins surface [29] . Surfactants like PEG 400 are amphiphilic molecules that contain both hydrophilic and lipophilic groups that can reduce surface tension and help to remove hydrophobic molecules and modify the structure and surface of lignocellulosic biomass [30] .…”

Evaluating the mechanism of milk protein as an efficient lignin blocker for boosting the enzymatic hydrolysis of lignocellulosic substrates

“…To overcome the non-productive absorption between lignin and cellulase for the improvement of enzymatic hydrolysis efficiency, additives such as non-ionic surfactants (e.g., Tween 80, Tween 20, and PEG), water-soluble lignin (e.g., lignosulfonate), and proteins (e.g., bovine serum albumin and soy protein) have been all proposed and tested. [19][20][21][22] These additives could be adsorbed by the surface lignin as well as the bulk residual lignin in the cell wall of pretreated biomass, thus blocking the non-productive adsorption between cellulase and lignin. 23 For example, Kapu et al found that the presence of PEG 6000 reduced the required cellulase loading by 77% and converted 97% of glucan and 44% of xylan in spent mushroom compost into monosaccharides.…”

“…, bovine serum albumin and soy protein) have been all proposed and tested. 19–22 These additives could be adsorbed by the surface lignin as well as the bulk residual lignin in the cell wall of pretreated biomass, thus blocking the non-productive adsorption between cellulase and lignin. 23 For example, Kapu et al found that the presence of PEG 6000 reduced the required cellulase loading by 77% and converted 97% of glucan and 44% of xylan in spent mushroom compost into monosaccharides.…”