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Depolymerization of lignocellulosic biomass is catalyzed by groups of enzymes whose action is influenced by substrate features and the composition of cellulase preparation. Cellulases contain a mixture of variety of enzymes, whose proportions dictate the saccharification of biomass. In the current study, four cellulase preparation varying in their composition were used to hydrolyze two types of alkali-treated biomass (aqueous ammonia-treated rice straw and sodium hydroxide-treated rice straw) to study the effect on catalytic rate, saccharification yields, and sugar release profile. We found that substrate features affected the extent of saccharification but had minimal effect on the sugar release pattern. In addition, complete hydrolysis to glucose was observed with enzyme preparation having at least a cellobiase units (CBU)/carboxymethyl cellulose (CMC) ratio (>0.15), while a modified enzyme ratio can be used for oligosaccharide synthesis. Thus, cellulase preparation with defined ratios of the three main enzymes can improve the saccharification which is of utmost importance in defining the success of lignocellulose-based economies. [ABSTRACT FROM PUBLISHER]

Controlled depolymerization of cellulose is essential for the production of valuable cellooligosaccharides and cellobiose from lignocellulosic biomass. However, enzymatic cellulose hydrolysis involves multiple synergistically acting enzymes, making difficult to control the depolymerization process and generate desired product. This work exploits the varying adsorption properties of the cellulase components to the cellulosic substrate and aims to control the enzyme activity. Cellulase adsorption was favored on pretreated cellulosic biomass as compared to synthetic cellulose. Preferential adsorption of exocellulases was observed over endocellulase, while β-glucosidases remained unadsorbed. Adsorbed enzyme fraction with bound exocellulases when used for hydrolysis generated cellobiose predominantly, while the unadsorbed enzymes in the liquid fraction produced cellooligosaccharides majorly, owing to its high endocellulases activity. Thus, the differential adsorption phenomenon of the cellulase components can be used for the controlling cellulose hydrolysis for the production of an array of sugars. [ABSTRACT FROM PUBLISHER]

• Alkali enzymatic extraction parameters influenced yield of soluble and insoluble dietary fibre (DF) • Yield of DF depends on concentration of enzyme and extraction time. • Alkali enzymatic extraction altered morphology of extracted soluble and insoluble DF. • Extracted soluble and insoluble DF as an fortificant for development of DF rich porridge. • Implementation of fuzzy analysis of developed DF rich rice porridge. Rice bran is abundant in dietary fiber and is often referred to as the seventh nutrient, recognized for its numerous health benefits. The objective of the current study is to investigate the extraction of both soluble and insoluble dietary fiber from defatted rice bran (DRB) using an alkali-enzymatic treatment through response surface methodology. The independent variables like substrate percentage (5–30 %), enzyme concentration (1–50 µL/g), and treatment time (2–12 h) and dependent variables were the yield of soluble and insoluble DF. The highest extraction yield was observed with alkali enzyme concentration (50 µL/g) treatment, resulting in 2 % SDF and 59.5 % IDF at 24 h of extraction. The results indicate that cellulase-AC enzyme aids in the hydrolysis of higher polysaccharides, leading to structural alterations in DRB and an increase in DF yield. Furthermore, the disruption of intra-molecular hydrogen bonding between oligosaccharides and the starch matrix helps to increase in DF yield, was also confirmed through FTIR and SEM. The extracted DF soluble and insoluble was then used to develop rice porridge. Sensory evaluation using fuzzy logic analysis reported the highest scores for samples containing 0.5 % insoluble DF and 1.25 % soluble DF. [ABSTRACT FROM AUTHOR]

β-glucosidases (BGs) are key enzymes in cellulose hydrolysis, being the rate-limiting enzyme that is regulated by feedback inhibition from its own product—glucose. Due to which low hydrolysis yields are observed thus affecting overall ethanol yield per ton biomass. In this study, hydrolysis yields influence as a function of BG deficiency, supplementation, and its synergy in cellulase cocktails were investigated. Results show that commercial cellulase preparations were low in BG and produce hydrolysis yields below 60 % in 12 h. On blending commercial preparations with BGs (from fungal and bacterial sources), the degree of synergism was observed greater than 1, indicating that the components depicted synergistic behaviour in the mixture. A triple blend cellulase cocktail comprising commercial preparation, and two different BG preparations were optimized using the mixture design approach based on the synergism demonstrated. According to the findings, the in-house optimized cocktail (C-Mix) was able to hydrolyze six different two-stage treated LBM feedstocks and release more than 900 mg/g of glucose. The stability of the optimized cocktail was also enhanced two-fold due to strong synergistic interactions. Thus, a simple blending of BGs in the commercial preparations can be a sustainable approach for developing effective cocktails and intensifying cellulose hydrolysis. [Display omitted] • Cellulase cocktail was optimized for two-stage treated lignocellulosic biomass. • The stability and glucose productivity were improved by the optimized cocktail. • Supplementation of BG with cellulase preparations was correlated to synergy. • Ratios of supplementation were correlated in enhancing the stability of the cocktail. [ABSTRACT FROM AUTHOR]

• The secretome of Penicillium funiculosum demonstrated potent saccharification. • Saccharification by derepressed P. funiculosum (Pf Mig188) was 2-fold higher. • Optimal saccharification was achieved at pH 4.0 and a temperature range of 45-55°C. • The Pf Mig188 secretome hydrolysed variety of alkali and acid pretreated biomasses. • The secretome demonstrated minimal product inhibition at a 20 % biomass load. PfMig188, a catabolically derepressed engineered strain of the hyper-cellulolytic fungus Penicillium funiculosum NCIM1228, was investigated for the efficacy of its secretome for biomass saccharification. An inexpensive version of media containing microcrystalline cellulose, wheat bran and soya protein was optimized for producing a high-quality secretome from the PfMig188 strain in both shake flasks and in a 20-L bioreactor. The activities of four classes of core cellulolytic enzymes required for saccharification in the PfMig188 secretome, namely, cellobiohydrolase (Avicelase activity), endoglucanase (CMCase activity), β-glucosidase (PNPGase activity) and xylanase (xylanase activity), were found to be 2.29 U/mL, 28.24 U/mL, 150 U/mL and 76 U/mL, respectively. The saccharification potential of the PfMig188 secretome was evaluated on rice straw and sugarcane bagasse pretreated with nitric acid and/or ammonium hydroxide. Saccharification performed using a 15 % (w/v) biomass load and a 3% (w/w) enzyme load released >100 g/L sugar in the hydrolysate, irrespective of the type of biomass and pre-treatment, with >80 % hydrolysis. Furthermore, the presence of lignin in nitric acid-pretreated biomass only marginally affected saccharification. Overall, the results demonstrated that the PfMig188 secretome, having relatively broad substrate specificity, is a viable and efficient substitute for T. reesei -based secretomes for diverse biomass saccharification. [ABSTRACT FROM AUTHOR]

Cellulases required for the conversion of biomass to sugars contribute to a significant part of the final bioethanol cost in the overall lignocellulosic biorefinery. It has been proven that recycling cellulases for saccharification is a viable method to lower the cost of the enzymatic hydrolysis process. Any method for recycling enzymes must begin with a stable cellulase cocktail that can withstand operational recycling conditions. The majority of commercial cellulase preparations contain a small quantity of β-glucosidases (BG), which lowers overall recyclability and causes low hydrolysis yields. This study examines the use of synergistic β-glucosidases (Atu BG3II and Pfu BG1 from Aspergillus tubingensis and Pyrococcus furiosus , respectively) to enhance the recyclability of cellulases during the hydrolysis process. It was able to recycle a significant amount of cellulases by recycling the insoluble solid fraction and liquid fraction following enzymatic hydrolysis of two-step treated wheat straw (ts-WS). In addition, the in-house cellulase cocktail (C-Mix) retained β-glucosidase activity and demonstrated glucose productivity of 18.9 g/L/h at 5% loading and enzyme efficiency (0.41 g of glucose per mg of protein) as Atu BG3II and Pfu BG1 did not adsorb significantly to the biomass. This resulted in a 3.5-fold improvement in the recyclability and a 33% increase in the hydrolysis yield during the study. Therefore, all these results signify better cellulase recovery using two-step treated lignocellulose and stable cellulase cocktails, demonstrating great potential for enzymatic recycling. [Display omitted] • Cellulase recyclability is affected by synergistic β-glucosidase supplementation. • Enzyme adsorbed solid residue can be recycled back enabling maximum enzyme recovery. • Atu BG3 and Pfu BG1 supplementation in cellulase AC led higher hydrolysis yield. • Two-step treatment lead to reduced biomass recalcitrance favouring recyclability. [ABSTRACT FROM AUTHOR]