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Wu D, Wang D, Hong J. Effect of a Novel Alpha/Beta Hydrolase Domain Protein on Tolerance of K. marxianus to Lignocellulosic Biomass Derived Inhibitors. Front Bioeng Biotechnol 2020; 8:844. [PMID: 32850717 PMCID: PMC7396682 DOI: 10.3389/fbioe.2020.00844] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/30/2020] [Indexed: 01/12/2023] Open
Abstract
The multiple inhibitors tolerance of microorganism is important in bioconversion of lignocellulosic biomass which is a promising renewable and sustainable source for biofuels and other chemicals. The disruption of an unknown α/β hydrolase, which was termed KmYME and located in mitochondria in this study, resulted in the yeast more susceptible to lignocellulose-derived inhibitors, particularly to acetic acid, furfural and 5-HMF. The KmYME disrupted strain lost more mitochondrial membrane potential, showed increased plasma membrane permeability, severer redox ratio imbalance, and increased ROS accumulation, compared with those of the non-disrupted strain in the presence of the same inhibitors. The intracellular concentration of ATP, NAD and NADP in the KmYME disrupted strain was decreased. However, disruption of KmYME did not result in a significant change of gene expression at the transcriptional level. The KmYME possessed esterase/thioesterase activity which was necessary for the resistance to inhibitors. In addition, KmYME was also required for the resistance to other stresses including ethanol, temperature, and osmotic pressure. Disruption of two possible homologous genes in S. cerevisiae also reduced its tolerance to inhibitors.
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Affiliation(s)
- Dan Wu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Dongmei Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory for Physical Sciences at the Microscale, Hefei, China
| | - Jiong Hong
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory for Physical Sciences at the Microscale, Hefei, China
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Rungrattanakasin B, Premjet S, Thanonkeo S, Klanrit P, Thanonkeo P. Cloning and expression of an endoglucanase gene from the thermotolerant fungus Aspergillus fumigatus DBiNU-1 in Kluyveromyces lactis. Braz J Microbiol 2018; 49:647-655. [PMID: 29449177 PMCID: PMC6066738 DOI: 10.1016/j.bjm.2017.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 09/30/2017] [Accepted: 10/14/2017] [Indexed: 11/24/2022] Open
Abstract
An intronless endoglucanase from thermotolerant Aspergillus fumigatus DBINU-1 was cloned, characterized and expressed in the yeast Kluyveromyces lactis. The full-length open reading frame of the endoglucanase gene from A. fumigatus DBiNU-1, designated Cel7, was 1383 nucleotides in length and encoded a protein of 460 amino acid residues. The predicted molecular weight and the isoelectric point of the A. fumigatus Cel7 gene product were 48.19 kDa and 5.03, respectively. A catalytic domain in the N-terminal region and a fungal type cellulose-binding domain/module in the C-terminal region were detected in the predicted polypeptide sequences. Furthermore, a signal peptide with 20 amino acid residues at the N-terminus was also detected in the deduced amino acid sequences of the endoglucanase from A. fumigatus DBiNU-1. The endoglucanase from A. fumigatus DBiNU-1 was successfully expressed in K. lactis, and the purified recombinant enzyme exhibited its maximum activity at pH 5.0 and 60 °C. The enzyme was very stable in a pH range from 4.0 to 8.0 and a temperature range from 30 to 60 °C. These features make it suitable for application in the paper, biofuel, and other chemical production industries that use cellulosic materials.
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Affiliation(s)
| | - Siripong Premjet
- Naresuan University, Faculty of Science, Department of Biology, Phitsanulok, Thailand
| | - Sudarat Thanonkeo
- Mahasarakham University, Walai Rukhavej Botanical Research Institute, Maha Sarakham, Thailand
| | - Preekamol Klanrit
- Khon Kaen University, Faculty of Technology, Department of Biotechnology, Khon Kaen, Thailand; Khon Kaen University, Faculty of Technology, Fermentation Research Center for Value Added Agricultural Products, Khon Kaen, Thailand
| | - Pornthap Thanonkeo
- Khon Kaen University, Faculty of Technology, Department of Biotechnology, Khon Kaen, Thailand; Khon Kaen University, Faculty of Technology, Fermentation Research Center for Value Added Agricultural Products, Khon Kaen, Thailand.
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3
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Zhang G, Lu M, Wang J, Wang D, Gao X, Hong J. Identification of hexose kinase genes in Kluyveromyces marxianus and thermo-tolerant one step producing glucose-free fructose strain construction. Sci Rep 2017; 7:45104. [PMID: 28338054 PMCID: PMC5364472 DOI: 10.1038/srep45104] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/16/2017] [Indexed: 01/01/2023] Open
Abstract
In yeast, the hexose assimilation is started at hexose phosphorylation. However, in Kluyveromyces marxianus, the hexokinase (HXK) and glucokinase (GLK) genes were not identified by experiments. Meanwhile, the glucose-free fructose product requires more cost-efficient method. In this study, the KmHXK1 and KmGLK1 genes were functionally identified through gene disruption, over-expression and recombinant enzymes characterization. Both glucose and fructose assimilation ability decreased significantly in KmHXK1 disrupted strain YLM001, however, this ability was not changed obviously in KmGLK1 disrupted strain YLM002. When over-expressing KmGLK1 in YLM001, only the glucose assimilation ability was recovered in obtained strain (YLM005). The kinetic constant analysis of recombinant enzymes also proved that KmHXK1 could phosphorylate glucose (Vmax 553.01 U/mg, Km 0.83 mM) and fructose (Vmax 609.82 U/mg, Km 0.52 mM), and KmGLK1 only phosphorylate glucose with a Vmax of 0.73 U/mg and a Km 4.09 mM. A thermo-tolerant strain YGR003 which produced glucose-free fructose from Jerusalem artichoke tuber in one step was constructed based on the obtained information. The highest production and fastest productivity were 234.44 g/L and 10.26 g/L/h, respectively, which were several folds of the results in previous reports.
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Affiliation(s)
- Guorong Zhang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Min Lu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Jichao Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Dongmei Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Xiaolian Gao
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Jiong Hong
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
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Isaac GS, Abu-Tahon MA. Enhanced alkaline cellulases production by the thermohalophilic Aspergillus terreus AUMC 10138 mutated by physical and chemical mutagens using corn stover as substrate. Braz J Microbiol 2016; 46:1269-77. [PMID: 26691490 PMCID: PMC4704614 DOI: 10.1590/s1517-838246420140958] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 05/06/2015] [Indexed: 11/22/2022] Open
Abstract
A thermohalophilic fungus, Aspergillus terreus AUMC 10138, isolated
from the Wadi El-Natrun soda lakes in northern Egypt was exposed successively to
gamma and UV-radiation (physical mutagens) and ethyl methan-sulfonate (EMS; chemical
mutagen) to enhance alkaline cellulase production under solid state fermentation
(SSF) conditions. The effects of different carbon sources, initial moisture,
incubation temperature, initial pH, incubation period, inoculum levels and different
concentrations of NaCl on production of alkaline filter paper activity (FPase),
carboxymethyl cellulase (CMCase) and β-glucosidase by the wild-type and mutant
strains of A. terreus were evaluated under SSF. The optimum
conditions for maximum production of FPase, CMCase and β-glucosidase were found to be
the corn stover: moisture ratio of 1:3(w/v), temperature 45 °C, pH range, 9.0–11.0,
and fermentation for 4, 4 and 7 day, respectively. Inoculum levels of 30% for
β-glucosidase and 40% for FPase, CMCase gave the higher cellulase production by the
wild-type and mutant strains, respectively. Higher production of all three enzymes
was obtained at a 5% NaCl. Under the optimized conditions, the mutant strain
A. terreus M-17 produced FPase (729 U/g), CMCase (1,783 U/g), and
β-glucosidase (342 U/g), which is, 1.85, 1.97 and 2.31-fold higher than the wild-type
strain. Our results confirmed that mutant strain M-17 could be a promising alkaline
cellulase enzyme producer employing lignocellulosics especially corn stover.
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Affiliation(s)
- George Saad Isaac
- Biological and Geological Sciences Department, Faculty of Education, Ain Shams University, Cairo, Egypt
| | - Medhat Ahmed Abu-Tahon
- Biological and Geological Sciences Department, Faculty of Education, Ain Shams University, Cairo, Egypt
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Boock JT, King BC, Taw MN, Conrado RJ, Siu KH, Stark JC, Walker LP, Gibson DM, DeLisa MP. Repurposing a bacterial quality control mechanism to enhance enzyme production in living cells. J Mol Biol 2015; 427:1451-1463. [PMID: 25591491 DOI: 10.1016/j.jmb.2015.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/30/2014] [Accepted: 01/05/2015] [Indexed: 11/25/2022]
Abstract
Heterologous expression of many proteins in bacteria, yeasts, and plants is often limited by low titers of functional protein. To address this problem, we have created a two-tiered directed evolution strategy in Escherichia coli that enables optimization of protein production while maintaining high biological activity. The first tier involves a genetic selection for intracellular protein stability that is based on the folding quality control mechanism inherent to the twin-arginine translocation pathway, while the second is a semi-high-throughput screen for protein function. To demonstrate the utility of this strategy, we isolated variants of the endoglucanase Cel5A, from the plant-pathogenic fungus Fusarium graminearum, whose production was increased by as much as 30-fold over the parental enzyme. This gain in production was attributed to just two amino acid substitutions, and it was isolated after two iterations through the two-tiered approach. There was no significant tradeoff in activity on soluble or insoluble cellulose substrates. Importantly, by combining the folding filter afforded by the twin-arginine translocation quality control mechanism with a function-based screen, we show enrichment for variants with increased protein abundance in a manner that does not compromise catalytic activity, providing a highly soluble parent for engineering of improved or new function.
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Affiliation(s)
- Jason T Boock
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Brian C King
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - May N Taw
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Robert J Conrado
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Ka-Hei Siu
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Jessica C Stark
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Larry P Walker
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Donna M Gibson
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA; Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - Matthew P DeLisa
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
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Seo JK, Park TS, Kwon IH, Piao MY, Lee CH, Ha JK. Characterization of Cellulolytic and Xylanolytic Enzymes of Bacillus licheniformis JK7 Isolated from the Rumen of a Native Korean Goat. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 26:50-8. [PMID: 25049705 PMCID: PMC4093055 DOI: 10.5713/ajas.2012.12506] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/02/2012] [Accepted: 10/26/2012] [Indexed: 12/01/2022]
Abstract
A facultative bacterium producing cellulolytic and hemicellulolytic enzymes was isolated from the rumen of a native Korean goat. The bacterium was identified as a Bacillus licheniformis on the basis of biochemical and morphological characteristics and 16S rDNA sequences, and has been designated Bacillus licheniformis JK7. Endoglucanase activities were higher than those of β-glucosidase and xylanase at all temperatures. Xylanase had the lowest activity among the three enzymes examined. The optimum temperature for the enzymes of Bacillus licheniformis JK7 was 70°C for endoglucanase (0.75 U/ml) and 50°C for β-glucosidase and xylanase (0.63 U/ml, 0.44 U/ml, respectively). All three enzymes were stable at a temperature range of 20 to 50°C. At 50°C, endoglucanse, β-glucosidase, and xylanase had 90.29, 94.80, and 88.69% residual activity, respectively. The optimal pH for the three enzymes was 5.0, at which their activity was 1.46, 1.10, and 1.08 U/ml, respectively. The activity of all three enzymes was stable in the pH range of 3.0 to 6.0. Endoglucanase activity was increased 113% by K+, while K+, Zn+, and tween 20 enhanced β-glucosidase activity. Xylanase showed considerable activity even in presence of selected chemical additives, with the exception of Mn2+ and Cu2+. The broad range of optimum temperatures (20 to 40°C) and the stability under acidic pH (4 to 6) suggest that the cellulolytic enzymes of Bacillus licheniformis JK7 may be good candidates for use in the biofuel industry.
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Affiliation(s)
- J K Seo
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
| | - T S Park
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
| | - I H Kwon
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
| | - M Y Piao
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
| | - C H Lee
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
| | - Jong K Ha
- Department of Agriculture Biotechnology, Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-742, Korea
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7
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Lulu L, Ling Z, Dongmei W, Xiaolian G, Hisanori T, Hidehiko K, Jiong H. Identification of a xylitol dehydrogenase gene from Kluyveromyces marxianus NBRC1777. Mol Biotechnol 2013; 53:159-69. [PMID: 22351371 DOI: 10.1007/s12033-012-9508-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Xylitol dehydrogenase (XDH) (EC 1.1.1.9) is one of the key enzymes in the xylose fermentation pathway in yeast and fungi. A xylitol dehydrogenase gene (XYL2) encoding a XDH was cloned from Kluyveromyces marxianus NBRC 1777, and the in vivo function was validated by disruption and complementation analysis. The highest activity of KmXDH could be observed at pH 9.5 during 55°C. The values of k(cat)/K(m) indicate that KmXDH prefers NAD(+) to NADP(+) (k(cat)/K(m NAD)(+) 3681/min mM and k(cat)/K(m NADP)(+) 1361/min mM). The different coenzyme preference between KmXR and KmXDH caused an accumulation of NADH in the xylose utilization pathway. The redox imbalance may be one of the reasons to cause the poor xylose fermentation under oxygen-limited conditions in K. marxianus NBRC1777.
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Affiliation(s)
- Li Lulu
- School of Life Science, University of Science and Technology of China, Hefei, 230027 Anhui, People's Republic of China
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8
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Cray JA, Bell ANW, Bhaganna P, Mswaka AY, Timson DJ, Hallsworth JE. The biology of habitat dominance; can microbes behave as weeds? Microb Biotechnol 2013; 6:453-92. [PMID: 23336673 PMCID: PMC3918151 DOI: 10.1111/1751-7915.12027] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/03/2012] [Indexed: 02/06/2023] Open
Abstract
Competition between microbial species is a product of, yet can lead to a reduction in, the microbial diversity of specific habitats. Microbial habitats can resemble ecological battlefields where microbial cells struggle to dominate and/or annihilate each other and we explore the hypothesis that (like plant weeds) some microbes are genetically hard-wired to behave in a vigorous and ecologically aggressive manner. These 'microbial weeds' are able to dominate the communities that develop in fertile but uncolonized--or at least partially vacant--habitats via traits enabling them to out-grow competitors; robust tolerances to habitat-relevant stress parameters and highly efficient energy-generation systems; avoidance of or resistance to viral infection, predation and grazers; potent antimicrobial systems; and exceptional abilities to sequester and store resources. In addition, those associated with nutritionally complex habitats are extraordinarily versatile in their utilization of diverse substrates. Weed species typically deploy multiple types of antimicrobial including toxins; volatile organic compounds that act as either hydrophobic or highly chaotropic stressors; biosurfactants; organic acids; and moderately chaotropic solutes that are produced in bulk quantities (e.g. acetone, ethanol). Whereas ability to dominate communities is habitat-specific we suggest that some microbial species are archetypal weeds including generalists such as: Pichia anomala, Acinetobacter spp. and Pseudomonas putida; specialists such as Dunaliella salina, Saccharomyces cerevisiae, Lactobacillus spp. and other lactic acid bacteria; freshwater autotrophs Gonyostomum semen and Microcystis aeruginosa; obligate anaerobes such as Clostridium acetobutylicum; facultative pathogens such as Rhodotorula mucilaginosa, Pantoea ananatis and Pseudomonas aeruginosa; and other extremotolerant and extremophilic microbes such as Aspergillus spp., Salinibacter ruber and Haloquadratum walsbyi. Some microbes, such as Escherichia coli, Mycobacterium smegmatis and Pseudoxylaria spp., exhibit characteristics of both weed and non-weed species. We propose that the concept of nonweeds represents a 'dustbin' group that includes species such as Synodropsis spp., Polypaecilum pisce, Metschnikowia orientalis, Salmonella spp., and Caulobacter crescentus. We show that microbial weeds are conceptually distinct from plant weeds, microbial copiotrophs, r-strategists, and other ecophysiological groups of microorganism. Microbial weed species are unlikely to emerge from stationary-phase or other types of closed communities; it is open habitats that select for weed phenotypes. Specific characteristics that are common to diverse types of open habitat are identified, and implications of weed biology and open-habitat ecology are discussed in the context of further studies needed in the fields of environmental and applied microbiology.
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Affiliation(s)
- Jonathan A Cray
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
| | - Andrew N W Bell
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
| | - Prashanth Bhaganna
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
| | - Allen Y Mswaka
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
| | - David J Timson
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
| | - John E Hallsworth
- School of Biological Sciences, MBC, Queen's University BelfastBelfast, BT9 7BL, Northern Ireland, UK
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Improving ethanol and xylitol fermentation at elevated temperature through substitution of xylose reductase in Kluyveromyces marxianus. J Ind Microbiol Biotechnol 2013; 40:305-16. [PMID: 23392758 DOI: 10.1007/s10295-013-1230-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
Thermo-tolerant yeast Kluyveromyces marxianus is able to utilize a wide range of substrates, including xylose; however, the xylose fermentation ability is weak because of the redox imbalance under oxygen-limited conditions. Alleviating the intracellular redox imbalance through engineering the coenzyme specificity of NADPH-preferring xylose reductase (XR) and improving the expression of XR should promote xylose consumption and fermentation. In this study, the native xylose reductase gene (Kmxyl1) of the K. marxianus strain was substituted with XR or its mutant genes from Pichia stipitis (Scheffersomyces stipitis). The ability of the resultant recombinant strains to assimilate xylose to produce xylitol and ethanol at elevated temperature was greatly improved. The strain YZB014 expressing mutant PsXR N272D, which has a higher activity with both NADPH and NADH as the coenzyme, achieved the best results, and produced 3.55 g l(-1) ethanol and 11.32 g l(-1) xylitol-an increase of 12.24- and 2.70-fold in product at 42 °C, respectively. A 3.94-fold increase of xylose consumption was observed compared with the K. marxianus YHJ010 harboring KmXyl1. However, the strain YZB015 expressing a mutant PsXR K21A/N272D, with which co-enzyme preference was completely reversed from NADPH to NADH, failed to ferment due to the low expression. So in order to improve xylose consumption and fermentation in K. marxianus, both higher activity and co-enzyme specificity change are necessary.
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Li CH, Wang HR, Yan TR. Cloning, purification, and characterization of a heat- and alkaline-stable endoglucanase B from Aspergillus niger BCRC31494. Molecules 2012; 17:9774-89. [PMID: 22893022 PMCID: PMC6269021 DOI: 10.3390/molecules17089774] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/09/2012] [Accepted: 08/10/2012] [Indexed: 11/29/2022] Open
Abstract
Endoglucanase B (EGLB) derived from Aspergillus niger BCRC31494 has been used in the food fermentation industry because of its thermal and alkaline tolerance. It was cloned and expressed in Pichia pastoris. According to sequence analysis, the gene open reading frame comprises 1,217 bp with five introns (GenBank GQ292753). According to sequence and protein domain analyses, EGLB was assigned to glycosyl hydrolase family 5 of the cellulase superfamily. Several binding sites were found in the promoter region. The purified recombinant enzyme was induced by 0.5% methanol, and it exhibited optimal activity at 70 °C and pH 4. EGLB was stable for 3 h at temperatures below 60 °C, with more than 90% of its activity remaining. The enzyme was specific for substrates with β-1,3 and β-1,4 linkages. In Lineweaver-Burk plot analysis, the Km and Vmax values of EGLB for β-D-glucan were 134 mg/mL and 4.68 U/min/mg, respectively. The enzyme activity was increased by 1.86-fold by Co2+ and by 2-fold by Triton X-100 and Tween 80. These favorable properties make EGLB a potential candidate for use in laundry and textile industrial applications.
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Affiliation(s)
| | | | - Tsong-Rong Yan
- Author to whom correspondence should be addressed; ; Tel.: +886-2-2182-2928 (ext. 6300); Fax: +886-2-2585-4735
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Kim HM, Lee YG, Patel DH, Lee KH, Lee DS, Bae HJ. Characteristics of bifunctional acidic endoglucanase (Cel5B) from Gloeophyllum trabeum. J Ind Microbiol Biotechnol 2012; 39:1081-9. [PMID: 22395898 DOI: 10.1007/s10295-012-1110-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 02/15/2012] [Indexed: 11/27/2022]
Abstract
The endoglucanase (Cel5B) from the filamentous fungus Gloeophyllum trabeum was cloned and expressed without a signal peptide, and alanine residue 22 converted to glutamine in Pichia pastoris GS115. The DNA sequence of Cel5B had an open reading frame of 1,077 bp, encoding a protein of 359 amino acid residues with a molecular weight of 47 kDa. On the basis of sequence similarity, Cel5B displayed active site residues at Glu-175 and Glu-287. Both residues lost full hydrolytic activity when replaced with alanine through point mutation. The purified recombinant Cel5B showed very high specific activity, about 80- to 1,000-fold and 13- to 70-fold in comparison with other endoglucanases and cellobiohydrolase, on carboxymethylcellulose and filter paper, respectively, at pH 3.5 and 55°C. Cel5B displayed bifunctional characteristics under acidic conditions. The kinetic properties of the enzyme determined using a Lineweaver-Burk plot indicated that Cel5B is a catalytically efficient cellulolytic enzyme. These results suggest that Cel5B has high bifunctional endo- and exoglucanase activity under acidic conditions and is a good candidate for bioconversion of lignocellulose.
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Affiliation(s)
- Ho Myeong Kim
- Department of Forest Products and Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea
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12
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Cloning and bioinformatics analysis of an endoglucanase gene (Aucel12A) from Aspergillus usamii and its functional expression in Pichia pastoris. J Ind Microbiol Biotechnol 2011; 39:347-57. [PMID: 21935697 DOI: 10.1007/s10295-011-1039-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 09/05/2011] [Indexed: 10/17/2022]
Abstract
Using 3' and 5' rapid amplification of cDNA ends methods, the full-length cDNA sequence encoding an endo-1,4-β-glucanase of Aspergillus usamii E001 (abbreviated as AuCel12A) was amplified from the total RNA. The clone cDNA sequence of the gene encoding the AuCel12A, named as Aucel12A, is 1,027 bp in length harboring 5' and 3' non-coding regions, as well as a 720 bp of open reading frame that encodes a 16-aa signal peptide, and a 223-aa mature AuCel12A with a theoretical M.W. of 24,294 Da, a calculated pI of 4.15, and one putative N-glycosylation site. The complete DNA sequence of the gene Aucel12A was amplified from the genomic DNA of A. usamii E001 by using the conventional PCR and pUCm-T vector-mediated PCR initially developed in our lab. The clone DNA sequence is 1,576 bp in length, consisting of a 5' flanking regulatory region, three exons, and two introns with sizes of 50 and 66 bp. The cDNA fragment encoding the mature AuCel12A was expressed in a fully active form in Pichia pastoris. One P. pastoris transformant expressing the highest recombinant AuCel12A (rAuCel12A) activity, labeled as P. pastoris GSCel2-1, was chosen for subsequent studies. Integration of the Aucel12A into P. pastoris genome was confirmed by PCR analysis using 5'- and 3'-AOX1 primers. SDS-PAGE and enzyme activity assays demonstrated that the rAuCel12A, a glycosylated protein with an apparent M.W. of 27.0 kDa and a carbohydrate content of 4.82%, was secreted into the culture medium. The purified rAuCel12A displayed the highest activity at pH 5.0 and 60°C. It was highly stable at a pH range of 3.5-7.0, and at a temperature of 55°C or below. Its activity was not significantly affected by an array of metal ions and EDTA, but inhibited by Ag⁺, Hg²⁺ and Fe²⁺. The K(m) and V(max) of the rAuCel12A, towards carboxymethylcellulose-Na (CMC-Na) at pH 5.0 and 50°C were 4.85 mg/ml and 160.5 U/mg, respectively.
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Zhang B, Zhang L, Wang D, Gao X, Hong J. Identification of a xylose reductase gene in the xylose metabolic pathway of Kluyveromyces marxianus NBRC1777. J Ind Microbiol Biotechnol 2011; 38:2001-10. [PMID: 21643709 DOI: 10.1007/s10295-011-0990-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/11/2011] [Indexed: 11/28/2022]
Abstract
Kluyveromyces marxianus is thermotolerant yeast that is able to utilize a wider range of substrates and has greater thermal tolerance than most other yeast species. K. marxianus can assimilate xylose, but its ability to produce ethanol from xylose in oxygen-limited environments is poor. In the present study, the K. marxianus xylose reductase (KmXR) gene (Kmxyl1) was cloned and the recombinant enzyme was characterized to clarify the factors that limit xylose fermentation in K. marxianus NBRC1777. KmXR is a key enzyme in the xylose metabolism of K. marxianus, which was verified by disruption of the Kmxyl1 gene. The Km of the recombinant KmXR for NADPH is 65.67 μM and KmXR activity is 1.295 U/mg, which is lower than those of most reported yeast XRs, and the enzyme has no activity with coenzyme NADH. This result demonstrates that the XR from K. marxianus is highly coenzyme specific; combined with the extremely low XDH activity of K. marxianus with NADP+, the limitation of xylose fermentation is due to a redox imbalance under anaerobic conditions and low KmXR activity.
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Affiliation(s)
- Biao Zhang
- School of Life Science, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China
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Identification of a xylulokinase catalyzing xylulose phosphorylation in the xylose metabolic pathway of Kluyveromyces marxianus NBRC1777. J Ind Microbiol Biotechnol 2011; 38:1739-46. [PMID: 21451977 DOI: 10.1007/s10295-011-0963-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Accepted: 03/12/2011] [Indexed: 10/24/2022]
Abstract
Xylulokinase is one of the key enzymes in xylose metabolism and fermentation, and fine-tuned expression of xylulokinase can improve xylose fermentation in yeast. To improve the efficiency of xylose fermentation in Kluyveromyces marxianus, the gene KmXYL3, which encodes a D: -xylulokinase (E.C. 2.7.1.17), was isolated from K. marxianus NBRC1777. KmXYL3 was expressed in Escherichia coli BL21 (DE3) cells, and the specific activity of the resulting recombinant purified xylulokinase was 23.5 mU/mg. Disruption of KmXYL3 resulted in both loss of xylitol utilization and marked decrease in xylose utilization, proving that KmXYL3 encodes a xylulokinase that catalyzes the reaction from xylulose to xylulose 5-phosphate in the xylose metabolic pathway. The slow assimilation of xylose observed in the KmXYL3-disrupted strain indicates that KmXYL3 is critical for xylose and xylitol utilization; however, K. marxianus utilizes a bypass pathway for xylose assimilation, and this pathway does not involve xylitol or xylulose.
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Sherief A, El-Tanash A, Atia N. Cellulase Production by Aspergillus fumigatus Grown on Mixed Substrate of Rice Straw and Wheat Bran. ACTA ACUST UNITED AC 2010. [DOI: 10.3923/jm.2010.199.211] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hong J, Wang Y, Kumagai H, Tamaki H. Construction of thermotolerant yeast expressing thermostable cellulase genes. J Biotechnol 2007; 130:114-23. [PMID: 17433483 DOI: 10.1016/j.jbiotec.2007.03.008] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 02/22/2007] [Accepted: 03/06/2007] [Indexed: 11/26/2022]
Abstract
Kluyveromyces marxianus NBRC1777 was identified as a thermotolerant yeast and was developed as a host for the expression of thermostable cellulase genes. The previously isolated genes for thermostable endo-beta-1,4-glucanase, cellobiohydrolase, and beta-glucosidase were introduced into the chromosome of K. marxianus and successfully expressed under the control of high-expression promoters. The recombinant K. marxianus expressing cellulase genes became able to grow in synthetic medium containing cellobiose or carboxymethyl-cellulose as the single carbon source. Moreover, the recombinant strain produced 43.4 g/L ethanol from 10% cellobiose. These results suggest that K. marxianus may afford a useful host system, which may be applicable to the simultaneous saccharification and fermentation and the foundation of cellulose consolidated bioprocessing.
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Affiliation(s)
- Jiong Hong
- Laboratory of Applied Microbiology, Research Institute of Natural Resources, Ishikawa Prefectural University, Nonoichi-cho, Ishikawa 921-8836, Japan
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