Understanding the promoting effect of non-catalytic protein on enzymatic hydrolysis efficiency of lignocelluloses

Abstract

Lignin deposits formed on the surface of pretreated lignocellulosic substrates during acidic pretreatments can non-productively adsorb costly enzymes and thereby influence the enzymatic hydrolysis efficiency of cellulose. In this article, peanut protein (PP), a biocompatible non-catalytic protein, was separated from defatted peanut flour (DPF) as a lignin blocking additive to overcome this adverse effect. With the addition of 2.5 g/L PP in enzymatic hydrolysis medium, the glucose yield of the bamboo substrate pretreated by phenylsulfonic acid (PSA) significantly increased from 38 to 94% at a low cellulase loading of 5 FPU/g glucan while achieving a similar glucose yield required a cellulase loading of 17.5 FPU/g glucan without PP addition. Similar promotion effects were also observed on the n-pentanol-pretreated bamboo and PSA-pretreated eucalyptus substrates. The promoting effect of PP on enzymatic hydrolysis was ascribed to blocking lignin deposits via hydrophobic and/or hydrogen-bonding interactions, which significantly reduced the non-productive adsorption of cellulase onto PSA lignin. Meanwhile, PP extraction also facilitated the utilization of residual DPF as the adhesive for producing plywood as compared to that without protein pre-extraction. This scheme provides a sustainable and viable way to improve the value of woody and agriculture biomass. Peanut protein, a biocompatible non-catalytic protein, can block lignin, improve enzymatic hydrolysis efficiency and thereby facilitate the economics of biorefinery. Graphical abstract

Polystyrene Sulfonate is Effective for Enhancing Biomass Enzymatic Saccharification Under Green Liquor Pretreatment in Bioenergy Poplar

“…), non-catalytic proteins (e.g. Bovine serum albumin (BSA) [8], peanut protein [9], and Amaranthus green proteins [10]), soluble lignin and derivatives [11][12][13][14].…”

Using poly(N-Vinylcaprolactam) to Improve the Enzymatic Hydrolysis Efficiency of Phenylsulfonic Acid-Pretreated Bamboo

“…The adsorption properties of cellulase and PNVCL on the PSA lignin film were evaluated by the quartz crystal microbalance (QCM) (Biolin Corp., Gothenburg, Sweden) ( Gong et al, 2021 ; Zheng et al, 2021 ). Initially, a PSA lignin film was prepared on the surface of the QCM gold sensor according to a reported spin-coating method ( Cai et al, 2017b ; Zheng et al, 2021 ).…”

“…In many cases, high enzyme loadings are still needed because hydrophobic lignin re-distributed or re-deposited on the surface of pretreated substrate would adsorb some of the enzymes ( Selig et al, 2007 ; Donohoe et al, 2008 ). As lignin has a higher adsorption capacity for cellulase than cellulose ( Ko et al, 2015 ), deposited lignin can competitively adsorbs enzyme molecules with cellulose, resulting in less enzyme molecules that can be used for cellulose hydrolysis ( Luo et al, 2019 ; Luo et al, 2020a ; Gong et al, 2021 ). As a result, more enzymes should be loaded for achieving considerable cellulose conversion, thereby increasing the processing cost of enzymatic hydrolysis.…”

Polystyrene sulfonate is effective for enhancing biomass enzymatic saccharification under green liquor pretreatment in bioenergy poplar

“…To improve the enzymatic hydrolysis efficiency and save the high cost of enzymes, some enzymatic promoting additives were brought in the enzymatic saccharification system, including surfactants (Tween [ 4 ], polyethylene glycol (PEG) [ 5 ], cetyltrimethylammonium bromide (CTAB) [ 6 ], Silwet L-77 [ 7 ], etc. ), non-catalytic proteins (e.g., bovine serum albumin (BSA) [ 8 ], peanut protein [ 9 ], and Amaranthus green proteins [ 10 ]), soluble lignin and derivatives [ 11 – 14 ].…”