Enzymes for Cellulosic Biomass Hydrolysis and Saccharification

2020 ◽  
pp. 283-326 ◽  
Author(s):  
Elmar M. Villota ◽  
Ziyu Dai ◽  
Yanpin Lu ◽  
Bin Yang
Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 220 ◽  
Author(s):  
Neha Srivastava ◽  
Rishabh Rathour ◽  
Sonam Jha ◽  
Karan Pandey ◽  
Manish Srivastava ◽  
...  

The biomass to biofuels production process is green, sustainable, and an advanced technique to resolve the current environmental issues generated from fossil fuels. The production of biofuels from biomass is an enzyme mediated process, wherein β-glucosidase (BGL) enzymes play a key role in biomass hydrolysis by producing monomeric sugars from cellulose-based oligosaccharides. However, the production and availability of these enzymes realize their major role to increase the overall production cost of biomass to biofuels production technology. Therefore, the present review is focused on evaluating the production and efficiency of β-glucosidase enzymes in the bioconversion of cellulosic biomass for biofuel production at an industrial scale, providing its mechanism and classification. The application of BGL enzymes in the biomass conversion process has been discussed along with the recent developments and existing issues. Moreover, the production and development of microbial BGL enzymes have been explained in detail, along with the recent advancements made in the field. Finally, current hurdles and future suggestions have been provided for the future developments. This review is likely to set a benchmark in the area of cost effective BGL enzyme production, specifically in the biorefinery area.


2012 ◽  
Vol 512-515 ◽  
pp. 421-425
Author(s):  
Jia Xin Liu ◽  
Yu Dong Huang

With the world’s focus on reducing our dependency on fossil fuel resources, one of the challenges will be the development of efficient catalysts for selective transformation of cellulosic biomass. Hydrolysis of cellulose to glucose is a key technology for effective use of lignocellulose because glucose can be efficiently converted into various chemicals, biofuels, foods, and medicines. Thus far, substantial efforts have been devoted to the degradation of cellulose but these processes have significant drawbacks. Some of these problems can potentially be overcome with the application of solid acid catalysts. In this paper, recent studies on heterogeneous acid-catalyzed hydrolysis of cellulose are summarized.


2020 ◽  
Author(s):  
Olusola A. Ogunyewo ◽  
Anmoldeep Randhawa ◽  
Mayank Gupta ◽  
Vemula Chandra Kaladhar ◽  
Praveen Kumar Verma ◽  
...  

AbstractLytic polysaccharide monooxygenases (LPMOs) are crucial industrial enzymes required in the biorefinery industry as well as in natural carbon cycle. These enzymes known to possess auxiliary activity are produced by numerous bacterial and fungal species to assist in the degradation of cellulosic biomass. In this study, we annotated and performed structural analysis of an uncharacterized thermostable LPMO from Penicillium funiculosum (PfLPMO9) in an attempt to understand nature of this enzyme in biomass degradation. PfLPMO9 exhibited 75% and 36% structural identity to Thermoascus aurantiacus (TaLPMO9A) and Lentinus similis (LsLPMO9A), respectively. Analysis of the molecular interactions during substrate binding revealed that PfLPMO9 demonstrated a higher binding affinity with a ΔG free energy of -46 k kcal/mol when compared with that of TaLPMO9A (−31 kcal/mol). The enzyme was further found to be highly thermostable at elevated temperature with a half-life of ∼88 h at 50 °C. Furthermore, multiple fungal genetic manipulation tools were employed to simultaneously overexpress this LPMO and Cellobiohydrolase I (CBH1) in catabolite derepressed strain of Penicillium funiculosum, PfMig188, in order to improve its saccharification performance towards acid pretreated wheat straw (PWS) at 20% substrate loading. The resulting transformants showed ∼200% and ∼66% increase in LPMO and Avicelase activities, respectively. While the secretomes of individually overexpressed LPMO and CBH1-strains increased saccharification of PWS by 6% and 13%, respectively, over PfMig188 at same enzyme concentration, the simultaneous overexpression of these two genes led to 20% increase in saccharification efficiency over PfMig188, which accounted for 82% saccharification of PWS at 20% substrate loading.ImportanceEnzymatic hydrolysis of cellulosic biomass by cellulases continues to be a significant bottleneck in the development of second-generation bio-based industries. While efforts are being intensified at how best to obtain indigenous cellulase for biomass hydrolysis, the high production cost of this enzyme remains a crucial challenge confronting its wide availability for efficient utilization of cellulosic materials. This is because it is challenging to get an enzymatic cocktail with balanced activity from a single host. This report provides for the first time the annotation and structural analysis of an uncharacterized thermostable lytic polysaccharide monooxygenase (LPMO) gene in Penicillium funiculosum and its impact in biomass deconstruction upon overexpression in catabolite derepressed strain of P. funiculosum. Cellobiohydrolase I (CBH1) which is the most important enzyme produced by many cellulolytic fungi for saccharification of crystalline cellulose was further overexpressed simultaneously with the LPMO. The resulting secretome was analyzed for enhanced LPMO and exocellulase activities with the corresponding improvement in its saccharification performance at high substrate loading by ∼20% using a minimal amount of protein.


2018 ◽  
Vol 17 (6) ◽  
pp. 1385-1398 ◽  
Author(s):  
Deepak K. Tuli ◽  
Ruchi Agrawal ◽  
Alok Satlewal ◽  
Anshu S. Mathur ◽  
Ravi P. Gupta ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Liang Sun ◽  
Jae Won Lee ◽  
Sangdo Yook ◽  
Stephan Lane ◽  
Ziqiao Sun ◽  
...  

AbstractPlant cell wall hydrolysates contain not only sugars but also substantial amounts of acetate, a fermentation inhibitor that hinders bioconversion of lignocellulose. Despite the toxic and non-consumable nature of acetate during glucose metabolism, we demonstrate that acetate can be rapidly co-consumed with xylose by engineered Saccharomyces cerevisiae. The co-consumption leads to a metabolic re-configuration that boosts the synthesis of acetyl-CoA derived bioproducts, including triacetic acid lactone (TAL) and vitamin A, in engineered strains. Notably, by co-feeding xylose and acetate, an enginered strain produces 23.91 g/L TAL with a productivity of 0.29 g/L/h in bioreactor fermentation. This strain also completely converts a hemicellulose hydrolysate of switchgrass into 3.55 g/L TAL. These findings establish a versatile strategy that not only transforms an inhibitor into a valuable substrate but also expands the capacity of acetyl-CoA supply in S. cerevisiae for efficient bioconversion of cellulosic biomass.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Valliappan Karuppiah ◽  
Lu Zhixiang ◽  
Hongyi Liu ◽  
Murugappan Vallikkannu ◽  
Jie Chen

Abstract Background Retention of agricultural bio-mass residues without proper treatment could affect the subsequent plant growth. In the present investigation, the co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens has been employed for multiple benefits including the enrichment of lignocellulose biodegradation, plant growth, defense potential and disease resistance. Results The Vel1 gene predominantly regulates the secondary metabolites, sexual and asexual development as well as cellulases and polysaccharide hydrolases productions. Overexpression mutant of the Trichoderma asperellum Vel1 locus (TA OE-Vel1) enhanced the activity of FPAase, CMCase, PNPCase, PNPGase, xylanase I, and xylanase II through the regulation of transcription regulating factors and the activation of cellulase and xylanase encoding genes. Further, these genes were induced upon co-cultivation with Bacillus amyloliquefaciens (BA). The co-culture of TA OE-Vel1 + BA produced the best composition of enzymes and the highest biomass hydrolysis yield of 89.56 ± 0.61%. The co-culture of TA OE-Vel1 + BA increased the corn stover degradation by the secretion of cellulolytic enzymes and maintained the C/N ratio of the corn stover amended soil. Moreover, the TA OE-Vel1 + BA increased the maize plant growth, expression of defense gene and disease resistance against Fusarium verticillioides and Cohilohorus herostrophus. Conclusion The co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens could be utilized as a profound and meaningful technique for the retention of agro residues and subsequent plant growth.


Author(s):  
Ornella M Ontañon ◽  
Soma Bedő ◽  
Silvina Ghio ◽  
Mercedes M Garrido ◽  
Juliana Topalian ◽  
...  

Abstract One of the main distinguishing features of bacteria belonging to the Cellulomonas genus is their ability to secrete multiple polysaccharide degrading enzymes. However, their application in biomass deconstruction still constitutes a challenge. We addressed the optimisation of the xylanolytic activities in extracellular enzymatic extracts of Cellulomonas sp. B6 and Cellulomonas fimi B-402 for their subsequent application in lignocellulosic biomass hydrolysis by culture in several substrates. As demonstrated by secretomic profiling, wheat bran and waste paper resulted to be suitable inducers for the secretion of xylanases of Cellulomonas sp. B6 and C. fimi B-402, respectively. Both strains showed high xylanolytic activity in culture supernatant although Cellulomonas sp. B6 was the most efficient xylanolytic strain. Upscaling from flasks to fermentation in a bench scale bioreactor resulted in equivalent production of extracellular xylanolytic enzymatic extracts and freeze drying was a successful method for concentration and conservation of the extracellular enzymes, retaining 80% activity. Moreover, enzymatic cocktails composed of combined extra and intracellular extracts effectively hydrolysed the hemicellulose fraction of extruded barley straw into xylose and xylooligosaccharides. Key points • Secreted xylanase activity of Cellulomonas sp. B6 and C. fimi was maximised. • Biomass-induced extracellular enzymes were identified by proteomic profiling. • Combinations of extra and intracellular extracts were used for barley straw hydrolysis.


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