Consolidated bioprocessing of lignocellulosic materials for cost-competitive bioenergy production

Author(s):  
Lew P Christopher
Fermentation ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 21 ◽  
Author(s):  
Sakae Horisawa ◽  
Akie Inoue ◽  
Yuka Yamanaka

The cost of bioethanol production from lignocellulosic materials is relatively high because the additional processes of delignification and saccharification are required. Consolidated bioprocessing (CBP) simultaneously uses the multiple processes of delignification, saccharification, and fermentation in a single reactor and has the potential to solve the problem of cost. Some wood-degrading basidiomycetes have lignin- and cellulose-degrading abilities as well as ethanol fermentation ability. The white rot fungus Schizophyllum commune NBRC 4928 was selected as a strong fermenter from a previous study. The lignin-degrading fungus Bjerkandera adusta and polysaccharide-degrading fungus Fomitopsis palustris were respectively added to S. commune ethanol fermentations to help degrade lignocellulosic materials. Bjerkandera adusta produced more ligninase under aerobic conditions, so a switching aeration condition was adopted. The mixed culture of S. commune and B. adusta promoted direct ethanol production from cedar wood. Fomitopsis palustris produced enzymes that released glucose from both carboxymethylcellulose and microcrystalline cellulose. The mixed culture of S. commune and F. palustris did not enhance ethanol production from cedar. The combination of S. commune and cellulase significantly increased the rate of ethanol production. The results suggest that CBP for ethanol production from cellulosic material can be achieved by using multiple fungi in one reactor.


2021 ◽  
Vol 2 (2) ◽  
pp. 287-310
Author(s):  
Daniel Gomes ◽  
Joana Cunha ◽  
Elisa Zanuso ◽  
José Teixeira ◽  
Lucília Domingues

Lignocellulosic residues have been receiving growing interest as a promising source of polysaccharides, which can be converted into a variety of compounds, ranging from biofuels to bioplastics. Most of these can replace equivalent products traditionally originated from petroleum, hence representing an important environmental advantage. Lignocellulosic materials are theoretically unlimited, cheaper and may not compete with food crops. However, the conversion of these materials to simpler sugars usually requires cellulolytic enzymes. Being still associated with a high cost of production, cellulases are commonly considered as one of the main obstacles in the economic valorization of lignocellulosics. This work provides a brief overview of some of the most studied strategies that can allow an important reduction of cellulases consumption, hence improving the economy of lignocellulosics conversion. Cellulases recycling is initially discussed regarding the main processes to recover active enzymes and the most important factors that may affect enzyme recyclability. Similarly, the potential of enzyme immobilization is analyzed with a special focus on the contributions that some elements of the process can offer for prolonged times of operation and improved enzyme stability and robustness. Finally, the emergent concept of consolidated bioprocessing (CBP) is also described in the particular context of a potential reduction of cellulases consumption.


2019 ◽  
Vol 34 (3-4) ◽  
pp. 311-335 ◽  
Author(s):  
Jinggang Guo ◽  
Peichen Gong ◽  
Runar Brännlund

2016 ◽  
Vol 20 (26) ◽  
pp. 2799-2809 ◽  
Author(s):  
Shiyang Fan ◽  
Panyue Zhang ◽  
Fan Li ◽  
Shuguang Jin ◽  
Siqi Wang ◽  
...  

2017 ◽  
Vol 14 (6) ◽  
pp. 778-784 ◽  
Author(s):  
Joanna Brzeska

Background: Cross-linking structure of polyurethanes determines no degradability of these materials. However, introducing the hydrolysable substrates (of natural or synthetic origin) into the cross-linked polyurethanes structure makes them biodegradable. Moreover compounds (such as polycaprolactone triol, glycerin, lysine triisocyanate, etc.) that are used for polyurethane cross-linking are degraded in non-toxic products. All these kinds of compounds can be introduced into soft or hard segments via urethane bonds. Objective: The review focuses on kind of multifunctional polyols and isocyanates, and low molecular crosslinkers used for cross-linked polyurethanes obtaining. These compounds are natural substrates (in the native state or after modification) or are synthetic compounds with degradable linkages. They belong to polyesters, plant oils, proteins, saccharides, and others (e.g. lignocellulosic materials), and they are synthesized chemically or via biosynthesis by algae, plants, microorganisms, and by animals. Conclusion: Incorporation of degradable groups (such as ester moieties) into the polymer structure, and using of substrates with the structure known and metabolized by microorganisms for soft or hard segments building, facilitate degradation of cross-linked polyurethanes.


2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Jingen Li ◽  
Shuying Gu ◽  
Zhen Zhao ◽  
Bingchen Chen ◽  
Qian Liu ◽  
...  

Abstract Background Lignocellulosic biomass has long been recognized as a potential sustainable source for industrial applications. The costs associated with conversion of plant biomass to fermentable sugar represent a significant barrier to the production of cost-competitive biochemicals. Consolidated bioprocessing (CBP) is considered a potential breakthrough for achieving cost-efficient production of biomass-based fuels and commodity chemicals. During the degradation of cellulose, cellobiose (major end-product of cellulase activity) is catabolized by hydrolytic and phosphorolytic pathways in cellulolytic organisms. However, the details of the two intracellular cellobiose metabolism pathways in cellulolytic fungi remain to be uncovered. Results Using the engineered malic acid production fungal strain JG207, we demonstrated that the hydrolytic pathway by β-glucosidase and the phosphorolytic pathway by phosphorylase are both used for intracellular cellobiose metabolism in Myceliophthora thermophila, and the yield of malic acid can benefit from the energy advantages of phosphorolytic cleavage. There were obvious differences in regulation of the two cellobiose catabolic pathways depending on whether M. thermophila JG207 was grown on cellobiose or Avicel. Disruption of Mtcpp in strain JG207 led to decreased production of malic acid under cellobiose conditions, while expression levels of all three intracellular β-glucosidase genes were significantly up-regulated to rescue the impairment of the phosphorolytic pathway under Avicel conditions. When the flux of the hydrolytic pathway was reduced, we found that β-glucosidase encoded by bgl1 was the dominant enzyme in the hydrolytic pathway and deletion of bgl1 resulted in significant enhancement of protein secretion but reduction of malate production. Combining comprehensive manipulation of both cellobiose utilization pathways and enhancement of cellobiose uptake by overexpression of a cellobiose transporter, the final strain JG412Δbgl2Δbgl3 produced up to 101.2 g/L and 77.4 g/L malic acid from cellobiose and Avicel, respectively, which corresponded to respective yields of 1.35 g/g and 1.03 g/g, representing significant improvement over the starting strain JG207. Conclusions This is the first report of detailed investigation of intracellular cellobiose catabolism in cellulolytic fungus M. thermophila. These results provide insights that can be applied to industrial fungi for production of biofuels and biochemicals from cellobiose and cellulose.


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