1
|
Guo H, Zhao Y, Chang JS, Lee DJ. Enzymes and enzymatic mechanisms in enzymatic degradation of lignocellulosic biomass: A mini-review. BIORESOURCE TECHNOLOGY 2023; 367:128252. [PMID: 36334864 DOI: 10.1016/j.biortech.2022.128252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
Enzymatic hydrolysis is the key step limiting the efficiency of the biorefinery of lignocellulosic biomass. Enzymes involved in enzymatic hydrolysis and their interactions with biomass should be comprehended to form the basis for looking for strategies to improve process efficiency. This article updates the contemporary research on the properties of key enzymes in the lignocellulose biorefinery and their interactions with biomass, adsorption, and hydrolysis. The advanced analytical techniques to track the interactions for exploiting mechanisms are discussed. The challenges and prospects for future research are outlined.
Collapse
Affiliation(s)
- Hongliang Guo
- College of Forestry, Northeast Forestry University, Harbin 150040, China
| | - Ying Zhao
- College of Forestry, Northeast Forestry University, Harbin 150040, China
| | - Jo-Shu Chang
- Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan; Department of Chemical and Materials Engineering, Tunghai University, Taichung 407, Taiwan
| | - Duu-Jong Lee
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-li 32003, Taiwan.
| |
Collapse
|
2
|
Jiang C, Wang H, Liu M, Wang L, Yang R, Wang P, Lu Z, Zhou Y, Zheng Z, Zhao G. Identification of chitin synthase activator in Aspergillus niger and its application in citric acid fermentation. Appl Microbiol Biotechnol 2022; 106:6993-7011. [PMID: 36149454 DOI: 10.1007/s00253-022-12174-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/02/2022]
Abstract
The biosynthesis of citric acid (CA) using Aspergillus niger as a carrier is influenced by mycelium morphology, which is determined by the expression level of morphology-related genes. As a key component of the fungal cell wall, chitin content has an important effect on morphogenesis, and to investigate the effects of this on fermentation performance, we used RNA interference to knockdown chitin synthase C (CHSC) and chitin synthase activator (CHS3) to obtain the single-gene mutant strains A. niger chs3 and chsC and the double mutant A. niger chs3C. We found that the CA fermentation performance of the two single mutants was significantly better than that of the double mutant. The mutant A. niger chs3-4 exhibited CA production potential compared to that of the parent strain in scale-up fermentation; we determined certain characteristics of CA high-yielding strain fermentation pellets. In addition, when chsC alone was silenced, there was very little change in chs3 mRNA levels, whereas those of chsC were significantly reduced when only chs3 was silenced. As this may be because of a synergistic effect between chsC and chs3, and we speculated that the latent activation target of CHS3 is CHSC, our results confirmed this hypothesis. This study is the first application of a separation and combination silence strategy of chitin synthase and chitin synthase activator in the morphology of A. niger CA fermentation. Furthermore, it provides new insights into the method for the morphological study of A. niger fermentation and the interaction of homologous genes. KEY POINTS: • The function of chitin synthase C (chsC) and chitin synthase activator (chs3) is tightly interrelated. • Mycelial morphology was optimized by knockdown of CHS3, resulting in the overproduction of citric acid. • The separation and combination silence strategies are promising tools for the interaction of homologous housekeeping genes.
Collapse
Affiliation(s)
- Chunxu Jiang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.,University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Han Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
| | - Menghan Liu
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Li Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China
| | - Ruwen Yang
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Peng Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China
| | - Zongmei Lu
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Yong Zhou
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China.
| | - Zhiming Zheng
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
| | - Genhai Zhao
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
| |
Collapse
|
3
|
Reppke MJ, Gerstner R, Windeisen-Holzhauser E, Richter K, Benz JP. Press water from the mechanical drying of Douglas-fir wood chips has multiple beneficial effects on lignocellulolytic fungi. Fungal Biol Biotechnol 2022; 9:10. [PMID: 35606847 PMCID: PMC9128199 DOI: 10.1186/s40694-022-00141-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/10/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND The mechanical drying of wood chips is an innovative method that improves the heating value of sawmill by-products in an energy-efficient continuous process. The liquid that comes out of the wood chips as press water (PW), however, contains a variety of undissolved as well as dissolved organic substances. The disposal of the PW as wastewater would generate additional costs due to its high organic load, offsetting the benefits in energy costs associated with the enhanced heating value of the wood chips. Our research explored if the organic load in PW could be utilized as a substrate by cellulolytic filamentous fungi. Hence, using the industrially relevant Ascomycete Trichoderma reesei RUT-C30 as well as several Basidiomycete wood-rotting fungi, we examined the potential of press water obtained from Douglas-fir wood chips to be used in the growth and enzyme production media. RESULTS The addition of PW supernatant to liquid cultures of T. reesei RUT-C30 resulted in a significant enhancement of the endoglucanase and endoxylanase activities with a substantially shortened lag-phase. A partial replacement of Ca2+, Mg2+, K+, as well as a complete replacement of Fe2+, Mn2+, Zn2+ by supplementing PW of the liquid media was achieved without negative effects on enzyme production. Concentrations of PW above 50% showed no adverse effects regarding the achievable endoglucanase activity but affected the endoxylanase activity to some extent. Exploring the enhancing potential of several individual PW components after chemical analysis revealed that the observed lag-phase reduction of T. reesei RUT-C30 was not caused by the dissolved sugars and ions, nor the wood particles in the PW sediment, suggesting that other, so far non-identified, compounds are responsible. However, also the growth rate of several basidiomycetes was significantly enhanced by the supplementation of raw PW to the agar medium. Moreover, their cultivation in liquid cultures reduced the turbidity of the PW substantially. CONCLUSIONS PW was identified as a suitable media supplement for lignocellulolytic fungi, including the cellulase and xylanase producer T. reesei RUT-C30 and several wood-degrading basidiomycetes. The possibility to replace several minerals, trace elements and an equal volume of fresh water in liquid media with PW and the ability of fungal mycelia to filter out the suspended solids is a promising way to combine biological wastewater treatment with value-adding biotechnological applications.
Collapse
Affiliation(s)
- Manfred J Reppke
- Professorship of Fungal Biotechnology in Wood Science, Holzforschung München (HFM), TUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany
| | - Rebecca Gerstner
- Professorship of Fungal Biotechnology in Wood Science, Holzforschung München (HFM), TUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany
| | - Elisabeth Windeisen-Holzhauser
- Chair of Wood Science, Holzforschung München (HFM), TUM School of Life Sciences, Technical University of Munich, Winzererstr. 45, 80797, Munich, Germany
| | - Klaus Richter
- Chair of Wood Science, Holzforschung München (HFM), TUM School of Life Sciences, Technical University of Munich, Winzererstr. 45, 80797, Munich, Germany
| | - J Philipp Benz
- Professorship of Fungal Biotechnology in Wood Science, Holzforschung München (HFM), TUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany.
- Institute for Advanced Study, Technical University of Munich, Lichtenbergstraße 2a, 85748, Garching, Germany.
| |
Collapse
|
4
|
It Works! Organic-Waste-Assisted Trichoderma spp. Solid-State Fermentation on Agricultural Digestate. Microorganisms 2022; 10:microorganisms10010164. [PMID: 35056614 PMCID: PMC8780502 DOI: 10.3390/microorganisms10010164] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/06/2022] [Accepted: 01/11/2022] [Indexed: 02/01/2023] Open
Abstract
This study aimed at valorizing digestate through Trichoderma spp. solid-state fermentation (SSF) to produce a potentially ameliorated fertilizer combined with fungal biomass as a value-added bioproduct. Plant-growth-promoting Trichoderma atroviride Ta13, T. reesei RUT-C30, T. asperellum R, and T. harzianum T-22 were tested on different SSF substrates: whole digestate (WD), digestate dried up with wood sawdust (SSF1), and digestate enriched with food waste and dried up with wood sawdust (SSF2). The fungal biomass was quantified by using a qPCR assay. The growth of the four Trichoderma spp. was only observed on the SSF2 substrate. The highest quantity of mycelium was produced by T. reesei RUT-30 (689.80 ± 80.53 mg/g substrate), followed by T. atroviride Ta13, and T. asperellum R (584.24 ± 13.36 and 444.79 ± 91.02 mg/g substrate). The germination of Lepidium sativum seeds was evaluated in order to assess the phytoxicity of the Trichoderma-enriched substrate. The treatments with 7.5% SSF2-R, 3.75% SSF2-T-22, and 1.8% SSF2-Ta13 equally enhanced the root elongation in comparison to the non-fermented SSF-2. This study demonstrated that digestate, mixed with agro-food waste, was able to support the cultivation of Trichoderma spp., paving the way to the valorization of fermented digestate as a proper biofertilizer.
Collapse
|
5
|
Hu Y, Li M, Liu Z, Song X, Qu Y, Qin Y. Carbon catabolite repression involves physical interaction of the transcription factor CRE1/CreA and the Tup1-Cyc8 complex in Penicillium oxalicum and Trichoderma reesei. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:244. [PMID: 34952627 PMCID: PMC8710005 DOI: 10.1186/s13068-021-02092-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 12/04/2021] [Indexed: 05/12/2023]
Abstract
BACKGROUND Cellulolytic enzyme production in filamentous fungi requires a release from carbon catabolite repression (CCR). The protein CRE1/CreA (CRE = catabolite responsive element) is a key transcription factor (TF) that is involved in CCR and represses cellulolytic gene expression. CRE1/CreA represents the functional equivalent of Mig1p, an important Saccharomyces cerevisiae TF in CCR that exerts its repressive effect by recruiting a corepressor complex Tup1p-Cyc8p. Although it is known from S. cerevisiae that CRE1/CreA might repress gene expression via interacting with the corepressor complex Tup1-Cyc8, this mechanism is unconfirmed in other filamentous fungi, since the physical interaction has not yet been verified in these organisms. The precise mechanism on how CRE1/CreA achieves transcriptional repression after DNA binding remains unknown. RESULTS The results from tandem affinity purification and bimolecular fluorescence complementation revealed a direct physical interaction between the TF CRE1/CreA and the complex Tup1-Cyc8 in the nucleus of cellulolytic fungus Trichoderma reesei and Penicillium oxalicum. Both fungi have the ability to secrete a complex arsenal of enzymes to synergistically degrade lignocellulosic materials. In P. oxalicum, the protein PoCyc8, a subunit of complex Tup1-Cyc8, interacts directly with TF PoCreA and histone H3 lysine 36 (H3K36) methyltransferase PoSet2 in the nucleus. The di-methylation level of H3K36 in the promoter of prominent cellulolytic genes (cellobiohydrolase-encoding gene Pocbh1/cel7A and endoglucanase-encoding gene Poegl1/cel7B) is positively correlated with the expression levels of TF PoCreA. Since the methylation of H3K36 was also demonstrated to be a repression marker of cellulolytic gene expression, it appears feasible that the cellulolytic genes are repressed via PoCreA-Tup1-Cyc8-Set2-mediated transcriptional repression. CONCLUSION This study verifies the long-standing conjecture that the TF CRE1/CreA represses gene expression by interacting with the corepressor complex Tup1-Cyc8 in filamentous fungi. A reasonable explanation is proposed that PoCreA represses gene expression by recruiting complex PoTup1-Cyc8. Histone methyltransferase Set2, which methylates H3K36, is also involved in the regulatory network by interacting with PoCyc8. The findings contribute to the understanding of CCR mechanism in filamentous fungi and could aid in biotechnologically relevant enzyme production.
Collapse
Affiliation(s)
- Yueyan Hu
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- NMPA Key Laboratory for Quality Research and Evaluation of Carbohydrate-Based Medicine, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| | - Mengxue Li
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| | - Zhongjiao Liu
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| | - Xin Song
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| | - Yinbo Qu
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| | - Yuqi Qin
- National Glycoengineering Research Center, State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
- NMPA Key Laboratory for Quality Research and Evaluation of Carbohydrate-Based Medicine, Shandong University, No. 72 Binhai Road, Qingdao, 266237 China
| |
Collapse
|
6
|
Buffo MM, Ferreira ALZ, Almeida RMRG, Farinas CS, Badino AC, Ximenes EA, Ladisch MR. Cellulolytic enzymes production guided by morphology engineering. Enzyme Microb Technol 2021; 149:109833. [PMID: 34311878 DOI: 10.1016/j.enzmictec.2021.109833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/11/2021] [Accepted: 05/19/2021] [Indexed: 11/26/2022]
Abstract
Endoglucanase and xylanase are critical enzymes for liquefaction and enzyme hydrolysis of high solids lignocellulosic biomass to facilitate its transport and production of desired derived products. Here is reported how combinations of different spore concentrations and pH influence microbial morphology, and how this may be used to direct expression and secretion of enzymes by Aspergillus niger. While xylanase production is not affected by A. niger morphology changes, endoglucanase production is enhanced under conditions of lower stress and by morphology that results in pellets. β-glucosidase production is enhanced under dispersed morphology, which results in up to fourfold increase of this enzyme production under the tested experimental conditions. A morphologic scale (Y) is proposed based on a form factor that considers the size and frequency of each morphology class, and that points to conditions that result in high selectivity for either endoglucanase or β-glucosidase production. An equation proposed to relate enzyme activity to morphology provides a useful tool for tuning enzyme production of A. niger, where morphology is a first indication of relative enzyme activities in a fermentation broth.
Collapse
Affiliation(s)
- Mariane M Buffo
- Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil
| | | | | | - Cristiane S Farinas
- Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil; Embrapa Instrumentation, Rua XV de Novembro 1452, São Carlos, SP, 13560-970, Brazil
| | - Alberto C Badino
- Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil.
| | | | | |
Collapse
|
7
|
Zhao Q, Liu Q, Wang Q, Qin Y, Zhong Y, Gao L, Liu G, Qu Y. Disruption of the Trichoderma reesei gul1 gene stimulates hyphal branching and reduces broth viscosity in cellulase production. J Ind Microbiol Biotechnol 2021; 48:6132311. [PMID: 33693788 PMCID: PMC9113457 DOI: 10.1093/jimb/kuab012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 02/05/2021] [Indexed: 12/03/2022]
Abstract
Hyphal morphology is considered to have a close relationship with the production
level of secreted proteins by filamentous fungi. In this study, the
gul1 gene, which encodes a putative mRNA-binding protein,
was disrupted in cellulase-producing fungus Trichoderma reesei.
The hyphae of Δgul1 strain produced more lateral
branches than the parent strain. Under the condition for cellulase production,
disruption of gul1 resulted in smaller mycelial clumps and
significantly lower viscosity of fermentation broth. In addition, cellulase
production was improved by 22% relative to the parent strain.
Transcriptome analysis revealed that a set of genes encoding cell wall
remodeling enzymes as well as hydrophobins were differentially expressed in the
Δgul1 strain. The results suggest that the
regulatory role of gul1 in cell morphogenesis is likely
conserved in filamentous fungi. To our knowledge, this is the first report on
the engineering of gul1 in an industrially important
fungus.
Collapse
Affiliation(s)
- Qinqin Zhao
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China
| | - Qin Liu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China
| | - Qi Wang
- National Glycoengineering Research Center, Shandong University, 27 Binhai Road, 266237 Qingdao, China
| | - Yuqi Qin
- National Glycoengineering Research Center, Shandong University, 27 Binhai Road, 266237 Qingdao, China
| | - Yaohua Zhong
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China
| | - Liwei Gao
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China.,Tobacco Research Institute of Chinese Academy of Agricultural Sciences, 11 Keyuanjingsi Road, 266101 Qingdao, China
| | - Guodong Liu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China.,National Glycoengineering Research Center, Shandong University, 27 Binhai Road, 266237 Qingdao, China
| | - Yinbo Qu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237 Qingdao, China.,National Glycoengineering Research Center, Shandong University, 27 Binhai Road, 266237 Qingdao, China
| |
Collapse
|
8
|
Novy V, Nielsen F, Cullen D, Sabat G, Houtman CJ, Hunt CG. The characteristics of insoluble softwood substrates affect fungal morphology, secretome composition, and hydrolytic efficiency of enzymes produced by Trichoderma reesei. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:105. [PMID: 33902680 PMCID: PMC8074412 DOI: 10.1186/s13068-021-01955-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/11/2021] [Indexed: 05/04/2023]
Abstract
BACKGROUND On-site enzyme production using Trichoderma reesei can improve yields and lower the overall cost of lignocellulose saccharification by exploiting the fungal gene regulatory mechanism that enables it to continuously adapt enzyme secretion to the substrate used for cultivation. To harness this, the interrelation between substrate characteristics and fungal response must be understood. However, fungal morphology or gene expression studies often lack structural and chemical substrate characterization. Here, T. reesei QM6a was cultivated on three softwood substrates: northern bleached softwood Kraft pulp (NBSK) and lodgepole pine pretreated either by dilute-acid-catalyzed steam pretreatment (LP-STEX) or mild alkaline oxidation (LP-ALKOX). With different pretreatments of similar starting materials, we presented the fungus with systematically modified substrates. This allowed the elucidation of substrate-induced changes in the fungal response and the testing of the secreted enzymes' hydrolytic strength towards the same substrates. RESULTS Enzyme activity time courses correlated with hemicellulose content and cellulose accessibility. Specifically, increased amounts of side-chain-cleaving hemicellulolytic enzymes in the protein produced on the complex substrates (LP-STEX; LP-ALKOX) was observed by secretome analysis. Confocal laser scanning micrographs showed that fungal micromorphology responded to changes in cellulose accessibility and initial culture viscosity. The latter was caused by surface charge and fiber dimensions, and likely restricted mass transfer, resulting in morphologies of fungi in stress. Supplementing a basic cellulolytic enzyme mixture with concentrated T. reesei supernatant improved saccharification efficiencies of the three substrates, where cellulose, xylan, and mannan conversion was increased by up to 27, 45, and 2800%, respectively. The improvement was most pronounced for proteins produced on LP-STEX and LP-ALKOX on those same substrates, and in the best case, efficiencies reached those of a state-of-the-art commercial enzyme preparation. CONCLUSION Cultivation of T. reesei on LP-STEX and LP-ALKOX produced a protein mixture that increased the hydrolytic strength of a basic cellulase mixture to state-of-the-art performance on softwood substrates. This suggests that the fungal adaptation mechanism can be exploited to achieve enhanced performance in enzymatic hydrolysis without a priori knowledge of specific substrate requirements.
Collapse
Affiliation(s)
- Vera Novy
- US Department of Agriculture, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI, 53726, USA.
- Department of Biology and Bioengineering, Division of Industrial Biotechnology, Chalmers University of Technology, Kemivägen 10, 412 96, Göteborg, Sweden.
| | - Fredrik Nielsen
- US Department of Agriculture, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI, 53726, USA
| | - Daniel Cullen
- US Department of Agriculture, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI, 53726, USA
| | - Grzegorz Sabat
- University of Wisconsin Biotechnology Center, Madison, WI, 53706, USA
| | - Carl J Houtman
- US Department of Agriculture, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI, 53726, USA
| | - Christopher G Hunt
- US Department of Agriculture, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI, 53726, USA
| |
Collapse
|
9
|
Yousef S, Kuliešienė N, Sakalauskaitė S, Nenartavičius T, Daugelavičius R. Sustainable green strategy for recovery of glucose from end-of-life euro banknotes. WASTE MANAGEMENT (NEW YORK, N.Y.) 2021; 123:23-32. [PMID: 33549877 DOI: 10.1016/j.wasman.2021.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 06/18/2020] [Accepted: 01/07/2021] [Indexed: 05/22/2023]
Abstract
Usually, Euro banknotes are made from cotton substrates and their waste is disposed of in landfill or is incinerated. In order to valorize the end-of-life euro banknotes (ELEBs), the substrates were used in this research for cellulase production via submerged fungal fermentation (SFF), and the resultant fungal cellulase w s used in ELEBs hydrolysis process for extraction of glucose. The experiments were started by exposing the ELEBs to different types of pretreatments, including milling process, alkali (NaOH/urea solution), and acid leaching to remove any contamination (e.g. dyes) and to decrease the crystallinity of cellulose (the main element in cotton substrate) thus increasing the degradation rate during the fermentation process. The effect of pretreatments on the morphology and chemical composition of ELEBs was observed using Scanning Electron Microscope and Energy Dispersive Spectrometry. Afterwards, Trichoderma reesei-DSM76 was used for cellulase production from the treated ELEBs with high cellulase activity (12.97 FPU/g). The resultant cellulase was upscaled in a bioreactor and used in ELEBs hydrolysis. Finally, the results showed that the optimized pretreatment methods (milling followed by leaching process) significantly improved the cellulase activity and glucose recovery, which was estimated by 96%. According to the obtained results, the developed strategy has a great potential for conversion of ELEBs into a glucose product that could be used in biofuels and bioplastics applications.
Collapse
Affiliation(s)
- Samy Yousef
- Department of Production Engineering, Faculty of Mechanical Engineering and Design, Kaunas University of Technology, LT-51424 Kaunas, Lithuania; Department of Materials Science, South Ural State University, Lenin Prospect 76, 454080 Chelyabinsk, Russia.
| | - Neringa Kuliešienė
- Department of Biochemistry, Vytautas Magnus University, Kaunas, Lithuania
| | | | | | | |
Collapse
|
10
|
Buffo MM, Esperança MN, Farinas CS, Badino AC. Relation between pellet fragmentation kinetics and cellulolytic enzymes production by Aspergillus niger in conventional bioreactor with different impellers. Enzyme Microb Technol 2020; 139:109587. [DOI: 10.1016/j.enzmictec.2020.109587] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/07/2020] [Accepted: 04/24/2020] [Indexed: 10/24/2022]
|
11
|
Novy V, Nielsen F, Seiboth B, Nidetzky B. The influence of feedstock characteristics on enzyme production in Trichoderma reesei: a review on productivity, gene regulation and secretion profiles. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:238. [PMID: 31624500 PMCID: PMC6781402 DOI: 10.1186/s13068-019-1571-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/20/2019] [Indexed: 05/21/2023]
Abstract
Biorefineries, designed for the production of lignocellulose-based chemicals and fuels, are receiving increasing attention from the public, governments, and industries. A major obstacle for biorefineries to advance to commercial scale is the high cost of the enzymes required to derive the fermentable sugars from the feedstock used. As summarized in this review, techno-economic studies suggest co-localization and integration of enzyme manufacturing with the cellulosic biorefinery as the most promising alternative to alleviate this problem. Thus, cultivation of Trichoderma reesei, the principal producer of lignocellulolytic enzymes, on the lignocellulosic biomass processed on-site can reduce the cost of enzyme manufacturing. Further, due to a complex gene regulation machinery, the fungus can adjust the gene expression of the lignocellulolytic enzymes towards the characteristics of the feedstock, increasing the hydrolytic efficiency of the produced enzyme cocktail. Despite extensive research over decades, the underlying regulatory mechanisms are not fully elucidated. One aspect that has received relatively little attention in literature is the influence the characteristics of a lignocellulosic substrate, i.e., its chemical and physical composition, has on the produced enzyme mixture. Considering that the fungus is dependent on efficient enzymatic degradation of the lignocellulose for continuous supply of carbon and energy, a relationship between feedstock characteristics and secretome composition can be expected. The aim of this review was to systematically collect, appraise, and aggregate data and integrate results from studies analyzing enzyme production by T. reesei on insoluble cellulosic model substrates and lignocellulosic biomass. The results show that there is a direct effect of the substrate's complexity (rated by structure, composition of the lignin-carbohydrate complex, and recalcitrance in enzymatic saccharification) on enzyme titers and the composition of specific activities in the secretome. It further shows that process-related factors, such as substrate loading and cultivation set-up, are direct targets for increasing enzyme yields. The literature on transcriptome and secretome composition further supports the proposed influence of substrate-related factors on the expression of lignocellulolytic enzymes. This review provides insights into the interrelation between the characteristics of the substrate and the enzyme production by T. reesei, which may help to advance integrated enzyme manufacturing of substrate-specific enzymes cocktails at scale.
Collapse
Affiliation(s)
- Vera Novy
- Institute of Biotechnology and Biochemical Engineering, NAWI Graz, Graz University of Technology, Graz, Austria
- Present Address: Department of Wood Science, Faculty of Forestry, The University of British Columbia, Vancouver, Canada
| | - Fredrik Nielsen
- Institute of Biotechnology and Biochemical Engineering, NAWI Graz, Graz University of Technology, Graz, Austria
- Present Address: Department of Wood Science, Faculty of Forestry, The University of British Columbia, Vancouver, Canada
| | - Bernhard Seiboth
- Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria
- Austrian Centre of Industrial Biotechnology (acib) GmbH, Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, NAWI Graz, Graz University of Technology, Graz, Austria
- Austrian Centre of Industrial Biotechnology (acib) GmbH, Graz, Austria
| |
Collapse
|
12
|
Fang X, Qu Y. Metabolic Engineering of Fungal Strains for Efficient Production of Cellulolytic Enzymes. FUNGAL CELLULOLYTIC ENZYMES 2018:27-41. [PMCID: PMC7120360 DOI: 10.1007/978-981-13-0749-2_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Filamentous fungi are widely used for production of cellulase and other cellulolytic enzymes. Metabolic engineering of filamentous fungal strains has been applied to improve enzyme production, and rapid progress has been made in the recent years. In this chapter, genetic tools and methods to develop superior enzyme producers are summarized, which includes establishment of genetic modification systems, selection and redesign of promoters, and metabolic engineering using either native transcription factors or artificial ones. In addition, enhancement of cellulase production through morphology engineering was also discussed. Emerging tools including CRISPR-Cas9-based genome editing and synthetic biology are highlighted, which are speeding up mechanisms elucidation and strain development, and will further facilitate economic cellulolytic enzyme production.
Collapse
Affiliation(s)
- Xu Fang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong China
| | - Yinbo Qu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong China
| |
Collapse
|
13
|
Zhang XY, Zi LH, Ge XM, Li YH, Liu CG, Bai FW. Development of Trichoderma reesei mutants by combined mutagenesis and induction of cellulase by low-cost corn starch hydrolysate. Process Biochem 2017. [DOI: 10.1016/j.procbio.2016.12.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|