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Zou S, Jia Y, He Q, Zhang K, Ban R, Hong J, Zhang M. Comparison of the Unfolded Protein Response in Cellobiose Utilization of Recombinant Angel- and W303-1A-Derived Yeast Expressing β-Glucosidase. Front Bioeng Biotechnol 2022; 10:837720. [PMID: 35433667 PMCID: PMC9008459 DOI: 10.3389/fbioe.2022.837720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
The unfolded protein response (UPR) is one of the most important protein quality control mechanisms in cells. At least, three factors are predicted to activate the UPR in yeast cells during fermentation. Using UPRE-lacZ as a reporter, we constructed two indicator strains, KZ and WZ, based on Angel-derived K-a and W303-1A strains, respectively, and investigated their UPR response to tunicamycin, ethanol, and acetic acid. Then, four strains carrying plasmids BG-cwp2 and BG were obtained to realize the displaying and secretion of β-glucosidase, respectively. The results of cellobiose utilization assays indicated interactions between the UPR and the metabolic burden between the strain source, anchoring moiety, oxygen supply, and cellobiose concentration. Meanwhile, as expected, growth (OD600), β-glucosidase, and β-galactosidase activities were shown to have a positive inter-relationship, in which the values of the KZ-derived strains were far lower than those of the WZ-derived strains. Additionally, extra metabolic burden by displaying over secreting was also much more serious in strain KZ than in strain WZ. The maximum ethanol titer of the four strains (KZ (BG-cwp2), KZ (BG), WZ (BG-cwp2), and WZ (BG)) in oxygen-limited 10% cellobiose fermentation was 3.173, 5.307, 5.495, and 5.486% (v/v), respectively, and the acetic acid titer ranged from 0.038 to 0.060% (v/v). The corresponding maximum values of the ratio of β-galactosidase activity to that of the control were 3.30, 5.29, 6.45, and 8.72, respectively. Under aerobic conditions with 2% cellobiose, those values were 3.79, 4.97, 6.99, and 7.67, respectively. A comparison of the results implied that β-glucosidase expression durably induced the UPR, and the effect of ethanol and acetic acid depended on the titer produced. Further study is necessary to identify ethanol- or acid-specific target gene expression. Taken together, our results indicated that the host strain W303-1A is a better secretory protein producer, and the first step to modify strain K-a for cellulosic ethanol fermentation would be to relieve the bottleneck of UPR capacity. The results of the present study will help to identify candidate host strains and optimize expression and fermentation by quantifying UPR induction.
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Affiliation(s)
- Shaolan Zou
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Tianjin, China
- *Correspondence: Shaolan Zou, ; Jiefang Hong,
| | - Yudie Jia
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Qing He
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Kun Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, China
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
| | - Rui Ban
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Tianjin, China
- *Correspondence: Shaolan Zou, ; Jiefang Hong,
| | - Minhua Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Tianjin, China
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Arnthong J, Ponjarat J, Bussadee P, Deenarn P, Prommana P, Phienluphon A, Charoensri S, Champreda V, Zhao XQ, Suwannarangsee S. Enhanced surface display efficiency of β-glucosidase in Saccharomyces cerevisiae by disruption of cell wall protein-encoding genes YGP1 and CWP2. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2021.108305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Zou S, Sun S, Zhang X, Li J, Guo J, Hong J, Ma Y, Zhang M. Repetitive δ-integration of a cellulase-encoding gene into the chromosome of an industrial Angel Yeast-derived strain by URA3 recycling. Biotechnol Appl Biochem 2020; 68:953-963. [PMID: 32658331 DOI: 10.1002/bab.1984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 06/25/2020] [Indexed: 11/07/2022]
Abstract
Genetic modification of industrial yeast strains often faces more difficulties than that of laboratory strains. Thus, new approaches are still required. In this research, the Angel Yeast-derived haploid strain Kα was genetically modified by multiple rounds of δ-integration, which was achieved via URA3 recycling. Three δ-integrative plasmids, pGδRU, pGδRU-BGL, and pGδRU-EG, were first constructed with two 167 bp δ sequences and a repeat-URA3-repeat fragment. Then, the δ-integrative strains containing the bgl1 or egl2 gene were successfully obtained by one-time transformation of the linearized pGδRU-BGL or pGδRU-EG fragment, respectively. Their counterparts in which the URA3 gene was looped out were also easily isolated by selection for growth on 5´-fluoroorotic acid plates, although the ratio of colonies lacking URA3 to the total number of colonies decreased with increasing copy number of the corresponding integrated cellulase-encoding gene. Similar results were observed during the second round of δ-integration, in which the δ-integration strain Kα(δ::bgl1-repeat) obtained from the first round was transformed with a linearized pGδRU-EG fragment. After 10 rounds of cell growth and transfer to fresh medium, the doubling times and enzyme activities of Kα(δ::bgl1-repeat), Kα(δ::egl2-repeat), and Kα(δ::bgl1-repeat)(δ::egl2-repeat) showed no significant change and were stable. Further, their maximum ethanol concentrations during simultaneous saccharification and fermentation of pretreated corncob over a 7-day period were 46.35, 33.13, and 51.77 g/L, respectively, which were all substantially higher than the parent Kα strain. Thus, repetitive δ-integration with URA3 recycling can be a feasible and valuable method for genetic engineering of Angel Yeast. These results also provide clues about some important issues related to δ-integration, such as the structural stability of δ-integrated genes and the effects of individual integration-site locations on gene expression. Further be elucidation of these issues should help to fully realize the potential of δ-integration-based methods in industrial yeast breeding.
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Affiliation(s)
- Shaolan Zou
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, People's Republic of China
| | - Sifan Sun
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, People's Republic of China
| | - Xiaomao Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, People's Republic of China
| | - Jiaman Li
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, People's Republic of China
| | - Jinghan Guo
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, People's Republic of China
| | - Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
| | - Yuanyuan Ma
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
| | - Minhua Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, People's Republic of China
- Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin, People's Republic of China
- State Key Laboratory of Engine, Tianjin University, Tianjin, People's Republic of China
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4
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Improved cellulase expression in diploid yeast strains enhanced consolidated bioprocessing of pretreated corn residues. Enzyme Microb Technol 2019; 131:109382. [DOI: 10.1016/j.enzmictec.2019.109382] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/27/2019] [Accepted: 07/12/2019] [Indexed: 01/12/2023]
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Ding J, Liang G, Zhang K, Hong J, Zou S, Lu H, Ma Y, Zhang M. Extra metabolic burden by displaying over secreting: Growth, fermentation and enzymatic activity in cellobiose of recombinant yeast expressing β-glucosidase. BIORESOURCE TECHNOLOGY 2018; 254:107-114. [PMID: 29413910 DOI: 10.1016/j.biortech.2017.12.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/09/2017] [Accepted: 12/11/2017] [Indexed: 06/08/2023]
Abstract
β-Glucosidase was selected to be a reporter to study metabolic burden imposed by its expression in yeast. Cell growth, fermentation yield and enzymatic activity were used as indicators of the metabolic burden borne by 14 recombinant yeast strains. Various factors were found to affect metabolic burden, including BGLI gene source, gene dose, trafficking of the enzyme (either cell-surface display or secretion), and oxygen supply. While BGLI gene from Aspergillus aculeatus provided better performance for the host cells than that from Saccharomycopsis fibuligera, displaying β-glucosidase on the cell surface generally led to lower μm, total activity and ethanol titer, and longer lag period, lower (aerobic condition) or higher (anaerobic condition) biomass yield than that of secreting β-glucosidase. The negative effect on growth increased with gene dose level until a final failure to grow. This growth difference implies that displaying β-glucosidase on the cell surface imposes an extra metabolic burden. The molecular basis and mechanisms for this phenomenon need to further be investigated in order to develop better strategies for utilizing displayed and secreted enzymes in biotechnology and yeast breeding.
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Affiliation(s)
- Juanjuan Ding
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Guohong Liang
- Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Kun Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China
| | - Shaolan Zou
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Haiyan Lu
- Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Yuanyuan Ma
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China
| | - Minhua Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Tianjin 300072, China; State Key Laboratory of Engine, Tianjin University, Tianjin 300072, China
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6
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Martínez-Patiño JC, Ruiz E, Romero I, Cara C, López-Linares JC, Castro E. Combined acid/alkaline-peroxide pretreatment of olive tree biomass for bioethanol production. BIORESOURCE TECHNOLOGY 2017; 239:326-335. [PMID: 28531858 DOI: 10.1016/j.biortech.2017.04.102] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/24/2017] [Accepted: 04/25/2017] [Indexed: 06/07/2023]
Abstract
Olive tree biomass (OTB) can be used for producing second generation bioethanol. In this work, extracted OTB was subjected to fractionation using a sequential acid/alkaline oxidative pretreatment. In the first acid stage, the effects of sulfuric acid concentration and reaction times at 130°C were investigated. Up to 71% solubilization of hemicellulosic sugars was achieved under optimized conditions (2.4% H2SO4, 84min). In the second stage, the influence of hydrogen peroxide concentration and process time were evaluated at 80°C. Approximately 80% delignification was achieved under the best operational conditions (7% H2O2, 90min) within the experimental range studied. This pretreatment produced a substrate with 72% cellulose that was highly accessible to enzymatic attack, yielding 82g glucose/100g glucose in delignified OTB. Ethanol production from both hemicellulosic sugars solubilized in the acid pretreatment and glucose from enzymatic hydrolysis of delignified OTB yielded 15g ethanol/100g OTB.
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Affiliation(s)
- José Carlos Martínez-Patiño
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Encarnación Ruiz
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Inmaculada Romero
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain.
| | - Cristóbal Cara
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Juan Carlos López-Linares
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Eulogio Castro
- Centre for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
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7
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Huang R, Guo H, Su R, Qi W, He Z. Enhanced cellulase recovery without β-glucosidase supplementation for cellulosic ethanol production using an engineered strain and surfactant. Biotechnol Bioeng 2016; 114:543-551. [DOI: 10.1002/bit.26194] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/30/2016] [Accepted: 09/26/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Renliang Huang
- Tianjin Engineering Center of Bio Gas/Oil Technology; School of Environmental Science and Engineering; Tianjin University; Tianjin China
| | - Hong Guo
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
| | - Rongxin Su
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
- Tianjin Key Laboratory of Membrane Science and Desalination Technology; Tianjin University; Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); Tianjin China
| | - Wei Qi
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
- Tianjin Key Laboratory of Membrane Science and Desalination Technology; Tianjin University; Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); Tianjin China
| | - Zhimin He
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
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8
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Wang J, Ma Y, Zhang K, Yang H, Liu C, Zou S, Hong J, Zhang M. Mating type and ploidy effect on the β-glucosidase activity and ethanol-producing performance of Saccharomyces cerevisiae with multiple δ-integrated bgl 1 gene. J Biotechnol 2016; 231:24-31. [DOI: 10.1016/j.jbiotec.2016.05.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/20/2016] [Accepted: 05/20/2016] [Indexed: 11/15/2022]
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9
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Ethanol production from acid- and alkali-pretreated corncob by endoglucanase and β-glucosidase co-expressing Saccharomyces cerevisiae subject to the expression of heterologous genes and nutrition added. World J Microbiol Biotechnol 2016; 32:86. [DOI: 10.1007/s11274-016-2043-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/01/2016] [Indexed: 10/22/2022]
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10
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Progress and challenges in the engineering of non-cellulolytic microorganisms for consolidated bioprocessing. Curr Opin Biotechnol 2015; 33:32-8. [DOI: 10.1016/j.copbio.2014.10.003] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/06/2014] [Accepted: 10/11/2014] [Indexed: 11/23/2022]
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11
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Guo H, Zou S, Liu B, Su R, Huang R, Qi W, Zhang M, He Z. Reducing β-glucosidase supplementation during cellulase recovery using engineered strain for successive lignocellulose bioconversion. BIORESOURCE TECHNOLOGY 2015; 187:362-368. [PMID: 25863900 DOI: 10.1016/j.biortech.2015.03.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 03/21/2015] [Accepted: 03/23/2015] [Indexed: 06/04/2023]
Abstract
Enzyme recycling by re-adsorption is one of the primary methods for reducing enzyme usage in lignocellulose conversion. This work proposes the combination of an engineered yeast strain that expresses β-glucosidase with enzyme recycling to reduce the amount of supplemented β-glucosidase in enzyme recycling experiments. Using the engineered strain, a slight increase in ethanol concentration was obtained after a 96-h fermentation of pretreated corncobs. Ethanol concentrations increased by 34.7% and 62.7% in the following two recycle rounds using the engineered strain compared with those using its parental strain without β-glucosidase addition. Furthermore, with the addition of β-glucosidase at 30CBU/g cellulose, the ethanol concentration after two recycle rounds exceeded 90% of that observed in the first SSF round with the engineered strain at a high initial cellulase loading of 45FPU/g cellulose.
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Affiliation(s)
- Hong Guo
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Shaolan Zou
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China
| | - Boshi Liu
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Rongxin Su
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
| | - Renliang Huang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Wei Qi
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Minhua Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
| | - Zhimin He
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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12
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Konishi M, Yoshida Y, Horiuchi JI. Efficient production of sophorolipids by Starmerella bombicola using a corncob hydrolysate medium. J Biosci Bioeng 2015; 119:317-22. [DOI: 10.1016/j.jbiosc.2014.08.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/23/2014] [Accepted: 08/12/2014] [Indexed: 10/24/2022]
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13
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Hong J, Yang H, Zhang K, Liu C, Zou S, Zhang M. Development of a cellulolytic Saccharomyces cerevisiae strain with enhanced cellobiohydrolase activity. World J Microbiol Biotechnol 2014; 30:2985-93. [PMID: 25164958 DOI: 10.1007/s11274-014-1726-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 08/20/2014] [Indexed: 11/27/2022]
Abstract
Consolidated bioprocessing (CBP) is a promising technology for lignocellulosic ethanol production, and the key is the engineering of a microorganism that can efficiently utilize cellulose. Development of Saccharomyces cerevisiae for CBP requires high level expression of cellulases, particularly cellobiohydrolases (CBH). In this study, to construct a CBP-enabling yeast with enhanced CBH activity, three cassettes containing constitutively expressed CBH-encoding genes (cbh1 from Aspergillus aculeatus, cbh1 and cbh2 from Trichoderma reesei) were constructed. T. reesei eg2, A. aculeatus bgl1, and the three CBH-encoding genes were then sequentially integrated into the S. cerevisiae W303-1A chromosome via δ-sequence-mediated integration. The resultant strains W1, W2, and W3, expressing uni-, bi-, and trifunctional cellulases, respectively, exhibited corresponding cellulase activities. Furthermore, both the activities and glucose producing activity ascended. The growth test on cellulose containing plates indicated that CBH was a necessary component for successful utilization of crystalline cellulose. The three recombinant strains and the control strains W303-1A and AADY were evaluated in acid- and alkali-pretreated corncob containing media with 5 FPU exogenous cellulase/g biomass loading. The highest ethanol titer (g/l) within 7 days was 5.92 ± 0.51, 18.60 ± 0.81, 28.20 ± 0.84, 1.40 ± 0.12, and 2.12 ± 0.35, respectively. Compared with the control strains, W3 efficiently fermented pretreated corncob to ethanol. To our knowledge, this is the first study aimed at creating cellulolytic yeast with enhanced CBH activity by integrating three types of CBH-encoding gene with a strong constitutive promoter Ptpi.
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Affiliation(s)
- Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, 300072, China
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14
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Yang H, Liu C, Zou S, Ma Y, Hong J, Zhang M. Improving bgl1 gene expression in Saccharomyces cerevisiae through meiosis in an isogenic triploid. Biotechnol Lett 2014; 36:1279-85. [PMID: 24563302 PMCID: PMC4000627 DOI: 10.1007/s10529-014-1471-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/09/2014] [Indexed: 12/01/2022]
Abstract
Introducing large numbers of target genes into the chromosome of Saccharomyces cerevisiae via δ-sequence-mediated integration is a good strategy for exploring the effects of gene dosage on expression and secretion of heterologous proteins. The expression of exogenous genes might be further improved through meiosis in an isogenic triploid. Here, a stable strain A-8 was screened from 35 sexual spore colonies obtained from an isogenic triploid integratively expressing bgl1 from Aspergillus aculeatus. The corresponding β-glucosidase activity in this strain was increased by ~120 % compared with the parent strain BGL-a. Measurement of doubling time, flow cytometry, and mating experiments further confirmed that A-8 was a spore-forming strain obtained from a triploid parent. Thus, combining δ-integration and meiosis in an isogenic triploid is a promising approach for improving the expression of exogenous proteins in S. cerevisiae.
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Affiliation(s)
- Huajun Yang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China,
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