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Shabbirahmed AM, Joel J, Gomez A, Patel AK, Singhania RR, Haldar D. Environment friendly emerging techniques for the treatment of waste biomass: a focus on microwave and ultrasonication processes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:79706-79723. [PMID: 37336854 DOI: 10.1007/s11356-023-28271-9] [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: 12/20/2022] [Accepted: 06/11/2023] [Indexed: 06/21/2023]
Abstract
In the recent past, an increasing interest is mostly observed in using microwave and ultrasonic irradiation to aid the biological conversion of waste materials into value-added products. This study is focused on various individual impacts of microwaves and ultrasonic waves for the treatment of biomass before the synthesis of value-added products. Following, a comprehensive review of the mechanisms governing microwaves and ultrasonication as the treatment methods, their effects on biomass disruption, solubilization of organic matter, modification of the crystalline structure, enzymatic hydrolysis and production of reducing sugars was performed. However, based on the lab-scale experiments evaluated, microwaves and ultrasonication were studied to be economically and energetically ineffective despite their beneficial effects on the waste biomass. This article reviews some of the difficulties associated with using microwaves and ultrasonic irradiation for the efficient processing of waste biomasses and identified some potential directions for future study.
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Affiliation(s)
- Asma Musfira Shabbirahmed
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, 641114, India
| | - Jesse Joel
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, 641114, India
| | - Anbu Gomez
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, 641114, India
| | - Anil Kumar Patel
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
- Centre for Energy and Environmental Sustainability, Lucknow, 226029, India
| | - Reeta Rani Singhania
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Dibyajyoti Haldar
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, 641114, India.
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Abstract
The depletion of fossil fuel resources and the negative impact of their use on the climate have resulted in the need for alternative sources of clean, sustainable energy. One available alternative, bioethanol, is a potential substitute for, or additive to, petroleum-derived gasoline. In the lignocellulose-to-bioethanol process, the cellulose hydrolysis step represents a major hurdle that hinders commercialization. To achieve economical production of bioethanol from lignocellulosic materials, the rate and yield of the enzymatic hydrolysis of cellulose, which is preferred over other chemically catalyzed processes, must be enhanced. To achieve this, product inhibition and enzyme loss, which are two major challenges, must be overcome. The implementation of membranes, which can permeate molecules selectively based on their size, offers a solution to this problem. Membrane bioreactors (MBRs) can enhance enzymatic hydrolysis yields and lower costs by retaining enzymes for repeated usage while permeating the products. This paper presents a critical discussion of the use of MBRs as a promising approach to the enhanced enzymatic hydrolysis of cellulosic materials. Various MBR configurations and factors that affect their performance are presented.
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Zhu Y, Liu Y, Ai M, Jia X. Surface display of carbonic anhydrase on Escherichia coli for CO 2 capture and mineralization. Synth Syst Biotechnol 2022; 7:460-473. [PMID: 34938905 PMCID: PMC8654698 DOI: 10.1016/j.synbio.2021.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 11/25/2021] [Accepted: 11/28/2021] [Indexed: 11/25/2022] Open
Abstract
Mineralization catalyzed by carbonic anhydrase (CA) is one of the most promising technologies for capturing CO2. In this work, Escherichia coli BL21(DE3) was used as the host, and the N-terminus of ice nucleation protein (INPN) was used as the carrier protein. Different fusion patterns and vectors were used to construct CA surface display systems for α-carbonic anhydrase (HPCA) from Helicobacter pylori 26695 and α-carbonic anhydrase (SazCA) from Sulfurihydrogenibium azorense. The surface display system in which HPCA was fused with INPN via a flexible linker and intermediate repeat sequences showed higher whole-cell enzyme activity, while the enzyme activity of the SazCA expression system was significantly higher than that of the HPCA expression system. The pET22b vector with the signal peptide PelB was more suitable for the cell surface display of SazCA. Cell fractionation and western-blot analysis indicated that SazCA and INPN were successfully anchored on the cell's outer membrane as a fusion protein. The enzyme activity of the surface display strain E-22b-IRLS (11.43 U·mL-1OD600 -1) was significantly higher than that of the intracellular expression strain E-22b-S (8.355 U·mL-1OD600 -1) under optimized induction conditions. Compared with free SazCA, E-22b-IRLS had higher thermal and pH stability. The long-term stability of SazCA was also significantly improved by surface display. When the engineered strain and free enzyme were used for CO2 mineralization, the amount of CaCO3 deposition catalyzed by the strain E-22b-IRLS on the surface (241 mg) was similar to that of the free SazCA and was significantly higher than the intracellular expression strain E-22b-S (173 mg). These results demonstrate that the SazCA surface display strain can serve as a whole-cell biocatalyst for CO2 capture and mineralization.
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Affiliation(s)
- Yinzhuang Zhu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China
| | - Yaru Liu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China
| | - Mingmei Ai
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China
| | - Xiaoqiang Jia
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, PR China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, PR China
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Lan Q, Duan Y, Wu P, Li X, Yu Y, Shi B, Zhou J, Lu H. Coordinately express hemicellulolytic enzymes in Kluyveromyces marxianus to improve the saccharification and ethanol production from corncobs. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:220. [PMID: 34809677 PMCID: PMC8607645 DOI: 10.1186/s13068-021-02070-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Hemicellulose acts as one factor contributing to the recalcitrance of lignocellulose that prevents cellulases to degrade the cellulose efficiently even in low quantities. Supplement of hemicellulases can enhance the performance of commercial cellulases in the enzymatic hydrolyses of lignocellulose. Kluyveromyce marxianus is an attractive yeast for cellulosic ethanol fermentation, as well as a promising host for heterologous protein production, since it has remarkable thermotolerance, high growth rate, and broad substrate spectrum etc. In this study, we attempted to coordinately express multiple hemicellulases in K. marxianus through a 2A-mediated ribosome skipping to self-cleave polyproteins, and investigated their capabilities for saccharification and ethanol production from corncobs. RESULTS Two polycistronic genes IMPX and IMPαX were constructed to test the self-cleavage of P2A sequence from the Foot-and-Mouth Disease virus (FMDV) in K. marxianus. The IMPX gene consisted of a β-mannanase gene M330 (without the stop codon), a P2A sequence and a β-xylanase gene Xyn-CDBFV in turn. In the IMPαX gene, there was an additional α-factor signal sequence in frame with the N-terminus of Xyn-CDBFV. The extracellular β-mannanase activities of the IMPX and IMPαX strains were 21.34 and 15.50 U/mL, respectively, but the extracellular β-xylanase activity of IMPαX strain was much higher than that of the IMPX strain, which was 136.17 and 42.07 U/mL, respectively. Subsequently, two recombinant strains, the IXPαR and IMPαXPαR, were constructed to coordinately and secretorily express two xylantic enzymes, Xyn-CDBFV and β-D-xylosidase RuXyn1, or three hemicellulolytic enzymes including M330, Xyn-CDBFV and RuXyn1. In fed-batch fermentation, extracellular activities of β-xylanase and β-xylosidase in the IXPαR strain were 1664.2 and 0.90 U/mL. Similarly, the IMPαXPαR strain secreted the three enzymes, β-mannanase, β-xylanase, and β-xylosidase, with the activities of 159.8, 2210.5, and 1.25 U/mL, respectively. Hemicellulolases of both strains enhanced the yields of glucose and xylose from diluted acid pretreated (DAP) corncobs when acted synergistically with commercial cellulases. In hybrid saccharification and fermentation (HSF) of DAP corncobs, hemicellulases of the IMPαXPαR strain increased the ethanol yield by 8.7% at 144 h compared with the control. However, both ethanol and xylose yields were increased by 12.7 and 18.2%, respectively, at 120 h in HSF of aqueous ammonia pretreated (AAP) corncobs with this strain. Our results indicated that coordinate expression of hemicellulolytic enzymes in K. marxianus promoted the saccharification and ethanol production from corncobs. CONCLUSIONS The FMDV P2A sequence showed high efficiency in self-cleavage of polyproteins in K. marxianus and could be used for secretory expression of multiple enzymes in the presence of their signal sequences. The IMPαXPαR strain coexpressed three hemicellulolytic enzymes improved the saccharification and ethanol production from corncobs, and could be used as a promising strain for ethanol production from lignocelluloses.
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Affiliation(s)
- Qing Lan
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
| | - Yitong Duan
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
| | - Pingping Wu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
| | - Xueyin Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
| | - Yao Yu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China
| | - Bo Shi
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Jungang Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China.
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China.
| | - Hong Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China.
- Shanghai Engineering Research Center of Industrial Microorganisms, Fudan University, 2005 Songhu Road, Shanghai, 200438, People's Republic of China.
- Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
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Defining the Frontiers of Synergism between Cellulolytic Enzymes for Improved Hydrolysis of Lignocellulosic Feedstocks. Catalysts 2021. [DOI: 10.3390/catal11111343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Lignocellulose has economic potential as a bio-resource for the production of value-added products (VAPs) and biofuels. The commercialization of biofuels and VAPs requires efficient enzyme cocktail activities that can lower their costs. However, the basis of the synergism between enzymes that compose cellulolytic enzyme cocktails for depolymerizing lignocellulose is not understood. This review aims to address the degree of synergism (DS) thresholds between the cellulolytic enzymes and how this can be used in the formulation of effective cellulolytic enzyme cocktails. DS is a powerful tool that distinguishes between enzymes’ synergism and anti-synergism during the hydrolysis of biomass. It has been established that cellulases, or cellulases and lytic polysaccharide monooxygenases (LPMOs), always synergize during cellulose hydrolysis. However, recent evidence suggests that this is not always the case, as synergism depends on the specific mechanism of action of each enzyme in the combination. Additionally, expansins, nonenzymatic proteins responsible for loosening cell wall fibers, seem to also synergize with cellulases during biomass depolymerization. This review highlighted the following four key factors linked to DS: (1) a DS threshold at which the enzymes synergize and produce a higher product yield than their theoretical sum, (2) a DS threshold at which the enzymes display synergism, but not a higher product yield, (3) a DS threshold at which enzymes do not synergize, and (4) a DS threshold that displays anti-synergy. This review deconvolutes the DS concept for cellulolytic enzymes, to postulate an experimental design approach for achieving higher synergism and cellulose conversion yields.
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Chan KL, Ko CH, Chang KL, Leu SY. Construction of a structural enzyme adsorption/kinetics model to elucidate additives associated lignin-cellulase interactions in complex bioconversion system. Biotechnol Bioeng 2021; 118:4065-4075. [PMID: 34245458 DOI: 10.1002/bit.27883] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/21/2021] [Accepted: 07/04/2021] [Indexed: 11/07/2022]
Abstract
Enzymatic hydrolysis is a rate-limiting process in lignocellulose biorefinery. The reaction involves complex enzyme-substrate and enzyme-lignin interactions in both liquid and solid phases, and has not been well characterized numerically. In this study, a kinetic model was developed to incorporate dynamic enzyme adsorption and product inhibition parameters into hydrolysis simulation. The enzyme adsorption coefficients obtained from Langmuir isotherm were fed dynamically into first-order kinetics for simulating the equilibrium enzyme adsorption in hydrolysis. A fractal and product inhibition kinetics was introduced and successfully applied to improve the simulation accuracy on adsorbed enzyme and glucose concentrations at different enzyme loadings, lignin contents, and in the presence of bovine serum albumin (BSA) and lysozyme. The model provided numerical proof quantifying the beneficial effects of both additives, which improved the hydrolysis rate by reducing the nonproductive adsorption of enzyme on lignin. The hydrolysis rate coefficient and fractal exponent both increased with increasing enzyme loadings, and lignin inhibition exhibited with increasing fractal exponent. Compared with BSA, the addition of lysozyme exhibited higher hydrolysis rates, which was reflected in the larger hydrolysis rate coefficients and smaller fractal exponents in the simulation. The model provides new insights to support process development, control, and optimization.
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Affiliation(s)
- Ka-Lai Chan
- Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Chun-Han Ko
- Research Institute for Sustainable Urban Development (RISUD), The Hong Kong Polytechnic University, Hung Hom, Hong Kong.,School of Forest and Resources Conservation, National Taiwan University, Taipei, Taiwan
| | - Ken-Lin Chang
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan
| | - Shao-Yuan Leu
- Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.,Research Institute for Sustainable Urban Development (RISUD), The Hong Kong Polytechnic University, Hung Hom, Hong Kong
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Ren S, Chen R, Wu Z, Su S, Hou J, Yuan Y. Enzymatic characteristics of immobilized carbonic anhydrase and its applications in CO 2 conversion. Colloids Surf B Biointerfaces 2021; 204:111779. [PMID: 33901810 DOI: 10.1016/j.colsurfb.2021.111779] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 04/12/2021] [Accepted: 04/18/2021] [Indexed: 01/01/2023]
Abstract
Native carbonic anhydrase (CA) has been widely used in several different applications due to its catalytic function in the interconversion of carbon dioxide (CO2) and carbonic acid. However, subject to its stability and recyclability, native CA often deactivates when in harsh environments, which restricts its applications in the commercial market. Maintaining the stability and high catalytic activity of CA is challenging. Immobilization provides an effective route that can improve enzymatic stability. Through the interaction of covalent bonds and van der Waals forces, water-soluble CA can be combined with various insoluble supports to form water-insoluble immobilized CA so that CA stability and utilization can be greatly improved. However, if the immobilization method or immobilization condition is not suitable, it often leads to a decrease in CA activity, reducing the application effects on CO2 conversion. In this review, we discuss existing immobilization methods and applications of immobilized CA in the environmental field, such as the mineralization of carbon dioxide and multienzyme cascade catalysis based on CA. Additionally, prospects in current development are outlined. Because of the many outstanding and superior properties after immobilization, CA is likely to be used in a wide variety of scientific and technical areas in the future.
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Affiliation(s)
- Sizhu Ren
- Langfang Normal University, College of Life Sciences, Langfang, 065000, No 100, Aimin West Road, Hebei Province, PR China; Technical Innovation Center for Utilization of Edible and Medicinal Fungi in Hebei Province, PR China; Edible and Medicinal Fungi Research and Development Center of Hebei Universities, PR China.
| | - Ruixue Chen
- Tianjin University of Science and Technology, College of Biotechnology, Tianjin, No 29, 13th, Avenue, 300457, Tianjin, PR China
| | - Zhangfei Wu
- Langfang Normal University, College of Life Sciences, Langfang, 065000, No 100, Aimin West Road, Hebei Province, PR China; Technical Innovation Center for Utilization of Edible and Medicinal Fungi in Hebei Province, PR China; Edible and Medicinal Fungi Research and Development Center of Hebei Universities, PR China
| | - Shan Su
- Langfang Normal University, College of Life Sciences, Langfang, 065000, No 100, Aimin West Road, Hebei Province, PR China
| | - Jiaxi Hou
- Langfang Normal University, College of Life Sciences, Langfang, 065000, No 100, Aimin West Road, Hebei Province, PR China
| | - Yanlin Yuan
- Langfang Normal University, College of Life Sciences, Langfang, 065000, No 100, Aimin West Road, Hebei Province, PR China.
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Baig KS. Interaction of enzymes with lignocellulosic materials: causes, mechanism and influencing factors. BIORESOUR BIOPROCESS 2020. [DOI: 10.1186/s40643-020-00310-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AbstractFor the production of biofuel (bioethanol), enzymatic adsorption onto a lignocellulosic biomass surface is a prior condition for the enzymatic hydrolysis process to occur. Lignocellulosic substances are mainly composed of cellulose, hemicellulose and lignin. The polysaccharide matrix (cellulose and hemicellulose) is capable of producing bioethanol. Therefore, lignin is removed or its concentration is reduced from the adsorption substrates by pretreatments. Selected enzymes are used for the production of reducing sugars from cellulosic materials, which in turn are converted to bioethanol. Adsorption of enzymes onto the substrate surface is a complicated process. A large number of research have been performed on the adsorption process, but little has been done to understand the mechanism of adsorption process. This article reviews the mechanisms of adsorption of enzymes onto the biomass surfaces. A conceptual adsorption mechanism is presented which will fill the gaps in literature and help researchers and industry to use adsorption more efficiently. The process of enzymatic adsorption starts with the reciprocal interplay of enzymes and substrates and ends with the establishment of molecular and cellular binding. The kinetics of an enzymatic reaction is almost the same as that of a characteristic chemical catalytic reaction. The influencing factors discussed in detail are: surface characteristics of the participating materials, the environmental factors, such as the associated flow conditions, temperature, concentration, etc. Pretreatment of lignocellulosic materials and optimum range of shear force and temperature for getting better results of adsorption are recommended.
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Enzymatic hydrolysis of cellulose using extracts from insects. Carbohydr Res 2019; 485:107811. [PMID: 31526927 DOI: 10.1016/j.carres.2019.107811] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/02/2019] [Accepted: 09/08/2019] [Indexed: 11/20/2022]
Abstract
The use of Zophobas morio extracts in the aspect of cellulose hydrolysis is presented for the first time. The aim of this study was to investigate the action of enzymes obtained from Z. morio on cellulose hydrolysis and to determine their influence on the structural properties of cellulose with use the Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Cellulose hydrolysis products were analyzed by high performance liquid chromatography (HPLC). This analysis indicated that microcrystalline cellulose with smaller particle size was more susceptible to enzymatically treatment. Moreover, our investigation of cellulase activity showed a different profile of the used enzyme during particular developmental stages of Z. morio. Midgut extracts obtained from adult insects are more effective in degrading cellulose than extracts from larvae. The analysis of cellulose hydrolysis confirms that the efficiency of this reaction also depends on the structure of cellulosic materials and internal conditions of enzymatic reaction. In this study the cellulolytic activity of Z. morio midgut extracts showed that these insects could be valuable sources of cellulases.
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Hefferon KL, Cantero‐Tubilla B, Brady J, Wilson D. Aromatic residues surrounding the active site tunnel of TfCel48A influence activity, processivity, and synergistic interactions with other cellulases. Biotechnol Bioeng 2019; 116:2463-2472. [DOI: 10.1002/bit.27086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 05/29/2019] [Accepted: 06/02/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Kathleen L. Hefferon
- Department of Cellular and Molecular GeneticsCornell University Ithaca New York
- Department of Food Science and TechnologyCornell University Ithaca New York
| | - Borja Cantero‐Tubilla
- Robert Frederick Smith School of Chemical and Biomolecular EngineeringCornell University Ithaca New York
| | - John Brady
- Department of Food Science and TechnologyCornell University Ithaca New York
| | - David Wilson
- Department of Cellular and Molecular GeneticsCornell University Ithaca New York
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Sukwong P, Sunwoo IY, Jeong DY, Kim SR, Jeong GT, Kim SK. Enhancement of bioethanol production from Gracilaria verrucosa by Saccharomyces cerevisiae through the overexpression of SNR84 and PGM2. Bioprocess Biosyst Eng 2019; 42:1421-1433. [PMID: 31055665 DOI: 10.1007/s00449-019-02139-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 04/26/2019] [Indexed: 12/13/2022]
Abstract
A total monosaccharide concentration of 47.0 g/L from 12% (w/v) Gracilaria verrucosa was obtained by hyper thermal acid hydrolysis with 0.2 M HCl at 140°C for 15 min and enzymatic saccharification with CTec2. To improve galactose utilization, we overexpressed two genes, SNR84 and PGM2, in a Saccharomyces cerevisiae CEN-PK2 using CRISPR/Cas-9. The overexpression of both SNR84 and PGM2 improved galactose utilization and ethanol production compared to the overexpression of each gene alone. The overexpression of both SNR84 and PGM2 and of PGM2 and SNR84 singly in S. cerevisiae CEN-PK2 Cas9 produced 20.0, 18.5, and 16.5 g/L ethanol with ethanol yield (YEtOH) values of 0.43, 0.39, and 0.35, respectively. However, S. cerevisiae CEN-PK2 adapted to high concentration of galactose consumed galactose completely and produced 22.0 g/L ethanol at a YEtOH value of 0.47. The overexpression of both SNR84 and PGM2 increased the transcriptional levels of GAL and regulatory genes; however, the transcriptional levels of these genes were lower than those in S. cerevisiae adapted to high galactose concentrations.
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Affiliation(s)
- Pailin Sukwong
- Department of Biotechnology, Pukyong National University, Busan, 48513, South Korea
| | - In Yung Sunwoo
- Department of Biotechnology, Pukyong National University, Busan, 48513, South Korea
| | - Deok Yeol Jeong
- Department of Food Science and Biotechnology, Kyungpook National University, Daegu, 37224, South Korea
| | - Soo Rin Kim
- Department of Food Science and Biotechnology, Kyungpook National University, Daegu, 37224, South Korea
| | - Gwi-Taek Jeong
- Department of Biotechnology, Pukyong National University, Busan, 48513, South Korea
| | - Sung-Koo Kim
- Department of Biotechnology, Pukyong National University, Busan, 48513, South Korea.
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12
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Liang C, Gu C, Karim MN, Holtzapple M. Kinetic modeling of countercurrent saccharification. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:179. [PMID: 31333760 PMCID: PMC6621958 DOI: 10.1186/s13068-019-1517-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/27/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND Countercurrent saccharification is a promising way to minimize enzyme loading while obtaining high conversions and product concentrations. However, in countercurrent saccharification experiments, 3-4 months are usually required to acquire a single steady-state data point. To save labor and time, simulation of this process is necessary to test various reaction conditions and determine the optimal operating point. Previously, a suitable kinetic model for countercurrent saccharification has never been reported. The Continuum Particle Distribution Modeling (CPDM) satisfactorily predicts countercurrent fermentation using mixed microbial cultures that digest various feedstocks. Here, CPDM is applied to countercurrent enzymatic saccharification of lignocellulose. RESULTS CPDM was used to simulate multi-stage countercurrent saccharifications of a lignocellulose model compound (α-cellulose). The modified HCH-1 model, which accurately predicts long-term batch saccharification, was used as the governing equation in the CPDM model. When validated against experimental countercurrent saccharification data, it predicts experimental glucose concentrations and conversions with the average errors of 3.5% and 4.7%, respectively. CPDM predicts conversion and product concentration with varying enzyme-addition location, total stage number, enzyme loading, liquid residence time (LRT), and solids loading rate (SLR). In addition, countercurrent saccharification was compared to batch saccharification at the same conversion, product concentration, and reactor volume. Results show that countercurrent saccharification is particularly beneficial when the product concentration is low. CONCLUSIONS The CPDM model was used to simulate multi-stage countercurrent saccharification of α-cellulose. The model predictions agreed well with the experimental glucose concentrations and conversions. CPDM prediction results showed that the enzyme-addition location, enzyme loading, LRT, and SLR significantly affected the glucose concentration and conversion. Compared to batch saccharification at the same conversion, product concentration, and reactor volume, countercurrent saccharification is particularly beneficial when the product concentration is low.
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Affiliation(s)
- Chao Liang
- Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122 USA
| | - Chao Gu
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX 77843-3122 USA
| | - M. Nazmul Karim
- Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122 USA
| | - Mark Holtzapple
- Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122 USA
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Lignocellulosic Biomass for Bioethanol Production Through Microbes: Strategies to Improve Process Efficiency. BIOFUEL AND BIOREFINERY TECHNOLOGIES 2019. [DOI: 10.1007/978-3-030-14463-0_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Corbett DB, Venditti R, Jameel H, Park S. Effect of Mechanical Refining Energy on the Enzymatic Digestibility of Lignocellulosic Biomass. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b02932] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Derek B. Corbett
- North Carolina State University, Department of Forest Biomaterials, 2820 Faucette Drive, Raleigh, North Carolina 27606, United States
| | - Richard Venditti
- North Carolina State University, Department of Forest Biomaterials, 2820 Faucette Drive, Raleigh, North Carolina 27606, United States
| | - Hasan Jameel
- North Carolina State University, Department of Forest Biomaterials, 2820 Faucette Drive, Raleigh, North Carolina 27606, United States
| | - Sunkyu Park
- North Carolina State University, Department of Forest Biomaterials, 2820 Faucette Drive, Raleigh, North Carolina 27606, United States
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Zhou J, Zhu P, Hu X, Lu H, Yu Y. Improved secretory expression of lignocellulolytic enzymes in Kluyveromyces marxianus by promoter and signal sequence engineering. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:235. [PMID: 30279722 PMCID: PMC6116501 DOI: 10.1186/s13068-018-1232-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 08/20/2018] [Indexed: 06/05/2023]
Abstract
BACKGROUND Taking into account its thermotolerance, high growth rate, and broad substrate spectrum, Kluyveromyces marxianus can be considered an ideal consolidated bioprocessing (CBP). A major obstacle to ethanol production using K. marxianus is the low production of lignocellulolytic enzymes, which reduces the cellulose hydrolysis and ethanol production. Thus, further improvement of enzyme expression and secretion is essential. RESULTS To improve the expression of lignocellulolytic enzymes, the inulinase promoter and signal sequence from K. marxianus was optimized through mutagenesis. A T(-361)A mutation inside the promoter, a deletion of AT-rich region inside 5'UTR (UTR∆A), and a P10L substitution in the signal sequence increased the secretory expression of the feruloyl esterase Est1E by up to sixfold. T(-361)A and UTR∆A increased the mRNA expression, while the P10L substitution extended the hydrophobic core of signal sequence and promoted secretion of mature protein. P10L and T(-361)A mutations increased secretory expressions of other types of lignocellulolytic enzymes by up to threefold, including endo-1,4-β-glucanase RuCelA, endo-1,4-β-endoxylanase Xyn-CDBFV, and endo-1,4-β-mannanase MAN330. During the fed-batch fermentation of strains carrying optimized modules, the peak activities of RuCelA, Xyn-CDBFV, MAN330, and Est1E reached 24 U/mL, 25,600 U/mL, 10,200 U/mL, and 1220 U/mL, respectively. Importantly, higher yield of enzymes by optimized promoter and signal sequence were achieved in all tested carbon sources, including the major end products of lignocellulose saccharification and fermentation, with growth on xylose resulting in the highest production. CONCLUSIONS The engineered promoter and signal sequence presented increased secretory expressions of different lignocellulolytic enzymes in K. marxianus by means of various carbon resources. Activities of lignocellulolytic enzymes in fed-batch fermentation were the highest activities reported for K. marxianus so far. Our engineered modules are valuable in producing lignocellulolytic enzymes by K. marxianus and in constructing efficient CBP strains for cellulosic ethanol production.
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Affiliation(s)
- Jungang Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438 China
| | - Peixia Zhu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438 China
| | - Xiaoyue Hu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438 China
| | - Hong Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438 China
- Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, 200237 China
| | - Yao Yu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438 China
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