51
|
de Witt RN, Kroukamp H, Volschenk H. Proteome response of two natural strains of Saccharomyces cerevisiae with divergent lignocellulosic inhibitor stress tolerance. FEMS Yeast Res 2019; 19:5145847. [PMID: 30371771 DOI: 10.1093/femsyr/foy116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/25/2018] [Indexed: 12/30/2022] Open
Abstract
Strains of Saccharomyces cerevisiae with improved tolerance to plant hydrolysates are of utmost importance for the cost-competitive production of value-added chemicals and fuels. However, engineering strategies are constrained by a lack of understanding of the yeast response to complex inhibitor mixtures. Natural S. cerevisiae isolates display niche-specific phenotypic and metabolic diversity, encoded in their DNA, which has evolved to overcome external stresses, utilise available resources and ultimately thrive in their challenging environments. Industrial and laboratory strains, however, lack these adaptations due to domestication. Natural strains can serve as a valuable resource to mitigate engineering constraints by studying the molecular mechanisms involved in phenotypic variance and instruct future industrial strain improvement to lignocellulosic hydrolysates. We, therefore, investigated the proteomic changes between two natural S. cerevisiae isolates when exposed to a lignocellulosic inhibitor mixture. Comparative shotgun proteomics revealed that isolates respond by regulating a similar core set of proteins in response to inhibitor stress. Furthermore, superior tolerance was linked to NAD(P)/H and energy homeostasis, concurrent with inhibitor and reactive oxygen species detoxification processes. We present several candidate proteins within the redox homeostasis and energy management cellular processes as possible targets for future modification and study. Data are available via ProteomeXchange with identifier PXD010868.
Collapse
Affiliation(s)
- R N de Witt
- Department of Microbiology, Stellenbosch University, De Beer Street, Stellenbosch, 7600, Western Cape, South Africa
| | - H Kroukamp
- Department of Molecular Sciences, Macquarie University, Balaclava Rd, North Ryde NSW 2109, Australia
| | - H Volschenk
- Department of Microbiology, Stellenbosch University, De Beer Street, Stellenbosch, 7600, Western Cape, South Africa
| |
Collapse
|
52
|
Protein expression analysis revealed a fine-tuned mechanism of in situ detoxification pathway for the tolerant industrial yeast Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2019; 103:5781-5796. [PMID: 31139900 DOI: 10.1007/s00253-019-09906-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022]
Abstract
Inhibitory compounds liberated from lignocellulose pretreatment are representative toxic chemicals that repress microbial growth and metabolism. A tolerant strain of the industrial yeast Saccharomyces cerevisiae is able to detoxify a major class of toxic compounds while producing ethanol. Knowledge on the yeast tolerance was mostly obtained by gene expression analysis and limited protein expression evidence is yet available underlying the yeast adaptation. Here we report a comparative protein expression profiling study on Y-50049, a tolerant strain compared with its parental industrial type strain Y-12632. We found a distinctive protein expression of glucose-6-phosphate dehydrogenase (Zwf1) in Y-50049 but not in Y-12632, in the relatively conserved glycolysis and pentose phosphate pathway (PPP) in response to a combinational challenge of 2-furaldehyde (furfural) and 5-hydroxymethyl-2-furaldehyde (HMF). A group of proteins with aldehyde reduction activity was uniquely induced expressed in Y-50049 but not in Y-12632. Such evidence allowed fine-tuning a mechanism of the renovated in situ detoxification by Y-50049. As the key protein, Zwf1 drove the glucose metabolism in favor of the oxidative branch of the PPP facilitating in situ detoxification of the toxic chemicals by Y-50049. The activated expression of Zwf1 generated the essential cofactor nicotinamide adenine dinucleotide phosphate (NADPH) enabling reduction of furfural and HMF through a group of aldehyde reduction enzymes. In return, the activate aldehyde reductions released desirable feedbacks of NADP+ stimulating continued oxidative activity of Zwf1. Thus, a well-maintained cofactor regeneration cycle was established to restore the cofactor imbalance caused by furfural-HMF. Challenges and perspectives on adaptation of significantly differential expressions of ribosomal proteins and other unique proteins are also discussed.
Collapse
|
53
|
Bioprospecting of Native Efflux Pumps To Enhance Furfural Tolerance in Ethanologenic Escherichia coli. Appl Environ Microbiol 2019; 85:AEM.02985-18. [PMID: 30635383 DOI: 10.1128/aem.02985-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 01/04/2019] [Indexed: 02/03/2023] Open
Abstract
Efficient microbial conversion of lignocellulose into valuable products is often hindered by the presence of furfural, a dehydration product of pentoses in hemicellulose sugar syrups derived from woody biomass. For a cost-effective lignocellulose microbial conversion, robust biocatalysts are needed that can tolerate toxic inhibitors while maintaining optimal metabolic activities. A comprehensive plasmid-based library encoding native multidrug resistance (MDR) efflux pumps, porins, and select exporters from Escherichia coli was screened for furfural tolerance in an ethanologenic E. coli strain. Small multidrug resistance (SMR) pumps, such as SugE and MdtJI, as well as a lactate/glycolate:H+ symporter, LldP, conferred furfural tolerance in liquid culture tests. Expression of the SMR pump potentially increased furfural efflux and cellular viability upon furfural assault, suggesting novel activities for SMR pumps as furfural efflux proteins. Furthermore, induced expression of mdtJI enhanced ethanol fermentative production of LY180 in the presence of furfural or 5-hydroxymethylfurfural, further demonstrating the applications of SMR pumps. This work describes an effective approach to identify useful efflux systems with desired activities for nonnative toxic chemicals and provides a platform to further enhance furfural efflux by protein engineering and mutagenesis.IMPORTANCE Lignocellulosic biomass, especially agricultural residues, represents an important potential feedstock for microbial production of renewable fuels and chemicals. During the deconstruction of hemicellulose by thermochemical processes, side products that inhibit cell growth and production, such as furan aldehydes, are generated, limiting cost-effective lignocellulose conversion. Here, we developed a new approach to increase cellular tolerance by expressing multidrug resistance (MDR) pumps with putative efflux activities for furan aldehydes. The developed plasmid library and screening methods may facilitate new discoveries of MDR pumps for diverse toxic chemicals important for microbial conversion.
Collapse
|
54
|
Fletcher E, Gao K, Mercurio K, Ali M, Baetz K. Yeast chemogenomic screen identifies distinct metabolic pathways required to tolerate exposure to phenolic fermentation inhibitors ferulic acid, 4-hydroxybenzoic acid and coniferyl aldehyde. Metab Eng 2018; 52:98-109. [PMID: 30471359 DOI: 10.1016/j.ymben.2018.11.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 01/30/2023]
Abstract
The conversion of plant material into biofuels and high value products is a two-step process of hydrolysing plant lignocellulose and next fermenting the sugars produced. However, lignocellulosic hydrolysis not only frees sugars for fermentation it simultaneously generates toxic chemicals, including phenolic compounds which severely inhibit yeast fermentation. To understand the molecular basis of phenolic compound toxicity, we performed genome-wide chemogenomic screens in Saccharomyces cerevisiae to identify deletion mutants that were either hypersensitive or resistant to three common phenolic compounds found in plant hydrolysates: coniferyl aldehyde, ferulic acid and 4-hydroxybenzoic acid. Despite being similar in structure, our screen revealed that yeast utilizes distinct pathways to tolerate phenolic compound exposure. Furthermore, although each phenolic compound induced reactive oxygen species (ROS), ferulic acid and 4-hydroxybenzoic acid-induced a general cytoplasmic ROS distribution while coniferyl aldehyde-induced ROS partially localized to the mitochondria and to a lesser extent, the endoplasmic reticulum. We found that the glucose-6-phosphate dehydrogenase enzyme Zwf1, which catalyzes the rate limiting step of pentose phosphate pathway, is required for reducing the accummulation of coniferyl aldehyde-induced ROS, potentially through the sequestering of Zwf1 to sites of ROS accumulation. Our novel insights into biological impact of three common phenolic inhibitors will inform the engineering of yeast strains with improved efficiency of biofuel and biochemical production in the presence hydrolysate-derived phenolic compounds.
Collapse
Affiliation(s)
- Eugene Fletcher
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Kai Gao
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Kevin Mercurio
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Mariam Ali
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Kristin Baetz
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5.
| |
Collapse
|
55
|
Cunha JT, Romaní A, Costa CE, Sá-Correia I, Domingues L. Molecular and physiological basis of Saccharomyces cerevisiae tolerance to adverse lignocellulose-based process conditions. Appl Microbiol Biotechnol 2018; 103:159-175. [PMID: 30397768 DOI: 10.1007/s00253-018-9478-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 11/27/2022]
Abstract
Lignocellulose-based biorefineries have been gaining increasing attention to substitute current petroleum-based refineries. Biomass processing requires a pretreatment step to break lignocellulosic biomass recalcitrant structure, which results in the release of a broad range of microbial inhibitors, mainly weak acids, furans, and phenolic compounds. Saccharomyces cerevisiae is the most commonly used organism for ethanol production; however, it can be severely distressed by these lignocellulose-derived inhibitors, in addition to other challenging conditions, such as pentose sugar utilization and the high temperatures required for an efficient simultaneous saccharification and fermentation step. Therefore, a better understanding of the yeast response and adaptation towards the presence of these multiple stresses is of crucial importance to design strategies to improve yeast robustness and bioconversion capacity from lignocellulosic biomass. This review includes an overview of the main inhibitors derived from diverse raw material resultants from different biomass pretreatments, and describes the main mechanisms of yeast response to their presence, as well as to the presence of stresses imposed by xylose utilization and high-temperature conditions, with a special emphasis on the synergistic effect of multiple inhibitors/stressors. Furthermore, successful cases of tolerance improvement of S. cerevisiae are highlighted, in particular those associated with other process-related physiologically relevant conditions. Decoding the overall yeast response mechanisms will pave the way for the integrated development of sustainable yeast cell-based biorefineries.
Collapse
Affiliation(s)
- Joana T Cunha
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Aloia Romaní
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Carlos E Costa
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Isabel Sá-Correia
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Lucília Domingues
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal.
| |
Collapse
|
56
|
Wang H, Li Q, Kuang X, Xiao D, Han X, Hu X, Li X, Ma M. Functions of aldehyde reductases from Saccharomyces cerevisiae in detoxification of aldehyde inhibitors and their biotechnological applications. Appl Microbiol Biotechnol 2018; 102:10439-10456. [PMID: 30306200 DOI: 10.1007/s00253-018-9425-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 09/28/2018] [Accepted: 09/28/2018] [Indexed: 11/25/2022]
Abstract
Bioconversion of lignocellulosic biomass to high-value bioproducts by fermentative microorganisms has drawn extensive attentions worldwide. Lignocellulosic biomass cannot be efficiently utilized by microorganisms, such as Saccharomyces cerevisiae, but has to be pretreated prior to fermentation. Aldehyde compounds, as the by-products generated in the pretreatment process of lignocellulosic biomass, are considered as the most important toxic inhibitors to S. cerevisiae cells for their growth and fermentation. Aldehyde group in the aldehyde inhibitors, including furan aldehydes, aliphatic aldehydes, and phenolic aldehydes, is identified as the toxic factor. It has been demonstrated that S. cerevisiae has the ability to in situ detoxify aldehydes to their corresponding less or non-toxic alcohols. This reductive reaction is catalyzed by the NAD(P)H-dependent aldehyde reductases. In recent years, detoxification of aldehyde inhibitors by S. cerevisiae has been extensively studied and a huge progress has been made. This mini-review summarizes the classifications and structural features of the characterized aldehyde reductases from S. cerevisiae, their catalytic abilities to exogenous and endogenous aldehydes and effects of metal ions, chemical protective additives, and salts on enzyme activities, subcellular localization of the aldehyde reductases and their possible roles in protection of the subcellular organelles, and transcriptional regulation of the aldehyde reductase genes by the key stress-response transcription factors. Cofactor preference of the aldehyde reductases and their molecular mechanisms and efficient supply pathways of cofactors, as well as biotechnological applications of the aldehyde reductases in the detoxification of aldehyde inhibitors derived from pretreatment of lignocellulosic biomass, are also included or supplemented in this mini-review.
Collapse
Affiliation(s)
- Hanyu Wang
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Qian Li
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Xiaolin Kuang
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Difan Xiao
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Xuebing Han
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Xiangdong Hu
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Xi Li
- College of Landscape Architecture, Sichuan Agricultural University, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China
| | - Menggen Ma
- Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, No. 211 Huimin Road, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China.
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Wenjiang, Chengdu, 611130, Sichuan, People's Republic of China.
| |
Collapse
|
57
|
Uranukul B, Woolston BM, Fink GR, Stephanopoulos G. Biosynthesis of monoethylene glycol in Saccharomyces cerevisiae utilizing native glycolytic enzymes. Metab Eng 2018; 51:20-31. [PMID: 30268818 DOI: 10.1016/j.ymben.2018.09.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 09/07/2018] [Accepted: 09/25/2018] [Indexed: 10/28/2022]
Abstract
Monoethylene glycol (MEG) is an important commodity chemical with applications in numerous industrial processes, primarily in the manufacture of polyethylene terephthalate (PET) polyester used in packaging applications. In the drive towards a sustainable chemical industry, bio-based production of MEG from renewable biomass has attracted growing interest. Recent attempts for bio-based MEG production have investigated metabolic network modifications in Escherichia coli, specifically rewiring the xylose assimilation pathways for the synthesis of MEG. In the present study, we examined the suitability of Saccharomyces cerevisiae, a preferred organism for industrial applications, as platform for MEG biosynthesis. Based on combined genetic, biochemical and fermentation studies, we report evidence for the existence of an endogenous biosynthetic route for MEG production from D-xylose in S. cerevisiae which consists of phosphofructokinase and fructose-bisphosphate aldolase, the two key enzymes in the glycolytic pathway. Further metabolic engineering and process optimization yielded a strain capable of producing up to 4.0 g/L MEG, which is the highest titer reported in yeast to-date.
Collapse
Affiliation(s)
- Boonsom Uranukul
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Whitehead Institute for Biomedical Research, Cambridge, MA 02139, United States
| | - Benjamin M Woolston
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Gerald R Fink
- Whitehead Institute for Biomedical Research, Cambridge, MA 02139, United States
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
| |
Collapse
|
58
|
Mertens JA, Kelly A, Hector RE. Screening for inhibitor tolerant Saccharomyces cerevisiae strains from diverse environments for use as platform strains for production of fuels and chemicals from biomass. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.biteb.2018.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
59
|
Engineering a spermidine biosynthetic pathway in Clostridium thermocellum results in increased resistance to furans and increased ethanol production. Metab Eng 2018; 49:267-274. [DOI: 10.1016/j.ymben.2018.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/27/2018] [Accepted: 09/04/2018] [Indexed: 12/29/2022]
|
60
|
The global regulator IrrE from Deinococcus radiodurans enhances the furfural tolerance of Saccharomyces cerevisiae. Biochem Eng J 2018. [DOI: 10.1016/j.bej.2018.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
61
|
Song B, Zhou Q, Xue HJ, Liu JJ, Zheng YY, Shen YB, Wang M, Luo JM. IrrE Improves Organic Solvent Tolerance and Δ 1-Dehydrogenation Productivity of Arthrobacter simplex. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:5210-5220. [PMID: 29746123 DOI: 10.1021/acs.jafc.8b01311] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
During steroid bioconversion, organic solvents are widely used for facilitating hydrophobic substrate dissolution in industry. Thus, strains that tolerate organic solvents are highly desirable. IrrE, a global transcriptional factor, was introduced into Arthrobacter simplex with Δ1-dehydrogenation ability. The results evidenced that IrrE did not affect cell biological traits and biotransformation performance under non-stress conditions. However, the recombinant strain achieved a productivity higher than that of the control strain in systems containing more ethanol and substrate, which coincided with cell viability under ethanol stress, the major stress factor during biotransformation. It also demonstrated that IrrE caused genome-wide transcriptional perturbation, and several defense proteins or systems were linked with higher organic solvent tolerance. IrrE simultaneously enhanced cell resistance to various stresses, and its horizontal impacts showed strain and stress dependence. In conclusion, the introduction of exogenous global regulators is an efficient approach to enhance organic solvent tolerance in steroid-transforming strains, resulting in higher productivity.
Collapse
Affiliation(s)
- Bo Song
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Qin Zhou
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Hai-Jie Xue
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Jia-Jia Liu
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Yuan-Yuan Zheng
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Yan-Bing Shen
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Min Wang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| | - Jian-Mei Luo
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Lab of Industrial Microbiology, College of Biotechnology , Tianjin University of Science and Technology , Tianjin 300457 , People's Republic of China
| |
Collapse
|
62
|
Liu ZL. Understanding the tolerance of the industrial yeast Saccharomyces cerevisiae against a major class of toxic aldehyde compounds. Appl Microbiol Biotechnol 2018; 102:5369-5390. [PMID: 29725719 DOI: 10.1007/s00253-018-8993-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 12/27/2022]
Abstract
Development of the next-generation biocatalyst is vital for fermentation-based industrial applications and a sustainable bio-based economy. Overcoming the major class of toxic compounds associated with lignocellulose-to-biofuels conversion is one of the significant challenges for new strain development. A significant number of investigations have been made to understand mechanisms of the tolerance for industrial yeast. It is humbling to learn how complicated the cell's response to the toxic chemicals is and how little we have known about yeast tolerance in the universe of the living cell. This study updates our current knowledge on the tolerance of industrial yeast against aldehyde inhibitory compounds at cellular, molecular and the genomic levels. It is comprehensive yet specific based on reproducible evidence and cross confirmed findings from different investigations using varied experimental approaches. This research approaches a rational foundation toward a more comprehensive understanding on the yeast tolerance. Discussions and perspectives are also proposed for continued exploring the puzzle of the yeast tolerance to aid the next-generation biocatalyst development.
Collapse
Affiliation(s)
- ZongLin Lewis Liu
- The US Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Bioenergy Research Unit, 1815 N University Street, Peoria, IL, 61604, USA.
| |
Collapse
|
63
|
Patulin biodegradation and quality improvement of apple puree fermented with Byssochlamys nivea FF1-2. FOOD BIOSCI 2018. [DOI: 10.1016/j.fbio.2017.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
64
|
Engineering of global regulators and cell surface properties toward enhancing stress tolerance in Saccharomyces cerevisiae. J Biosci Bioeng 2017; 124:599-605. [DOI: 10.1016/j.jbiosc.2017.06.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 01/22/2023]
|
65
|
Wang X, Khushk I, Xiao Y, Gao Q, Bao J. Tolerance improvement of Corynebacterium glutamicum on lignocellulose derived inhibitors by adaptive evolution. Appl Microbiol Biotechnol 2017; 102:377-388. [DOI: 10.1007/s00253-017-8627-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/24/2017] [Accepted: 11/06/2017] [Indexed: 01/09/2023]
|
66
|
Wu G, Xu Z, Jönsson LJ. Profiling of Saccharomyces cerevisiae transcription factors for engineering the resistance of yeast to lignocellulose-derived inhibitors in biomass conversion. Microb Cell Fact 2017; 16:199. [PMID: 29137634 PMCID: PMC5686817 DOI: 10.1186/s12934-017-0811-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 11/04/2017] [Indexed: 11/24/2022] Open
Abstract
Background Yeast transcription factors (TFs) involved in the regulation of multidrug resistance (MDR) were investigated in experiments with deletion mutants, transformants overexpressing synthetic genes encoding TFs, and toxic concentrations of lignocellulose-derived substances added to cultures as complex mixtures or as specific compounds, viz. coniferyl aldehyde, 5-hydroxymethylfurfural, and furfural. Results In the presence of complex mixtures of toxic substances from spruce wood, transformants overexpressing YAP1 and STB5, TFs involved in oxidative stress response, exhibited enhanced relative growth rates amounting to 4.589 ± 0.261 and 1.455 ± 0.185, respectively. Other TFs identified as important for resistance included DAL81, GZF3, LEU3, PUT3, and WAR1. Potential overlapping functions of YAP1 and STB5 were investigated in experiments with permutations of deletions and overexpression of the two genes. YAP1 complemented STB5 with respect to resistance to 5-hydroxymethylfurfural, but had a distinct role with regard to resistance to coniferyl aldehyde as deletion of YAP1 rendered the cell incapable of resisting coniferyl aldehyde even if STB5 was overexpressed. Conclusions We have investigated 30 deletion mutants and eight transformants overexpressing MDR transcription factors with regard to the roles the transcription factors play in the resistance to toxic concentrations of lignocellulose-derived substances. This work provides an overview of the involvement of thirty transcription factors in the resistance to lignocellulose-derived substances, shows distinct and complementary roles played by YAP1 and STB5, and offers directions for the engineering of robust yeast strains for fermentation processes based on lignocellulosic feedstocks.![]() Electronic supplementary material The online version of this article (10.1186/s12934-017-0811-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Guochao Wu
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden.
| | - Zixiang Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Leif J Jönsson
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden
| |
Collapse
|
67
|
Paramasivan K, Mutturi S. Regeneration of NADPH Coupled with HMG-CoA Reductase Activity Increases Squalene Synthesis in Saccharomyces cerevisiae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:8162-8170. [PMID: 28845666 DOI: 10.1021/acs.jafc.7b02945] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Although overexpression of the tHMG1 gene is a well-known strategy for terpene synthesis in Saccharomyces cerevisiae, the optimal level for tHMG1p has not been established. In the present study, it was observed that two copies of the tHMG1 gene on a dual gene expression cassette improved squalene synthesis in laboratory strain by 16.8-fold in comparison to single-copy expression. It was also observed that tHMG1p is limited by its cofactor (NADPH), as the overexpression of NADPH regenerating genes', viz., ZWF1 and POS5 (full length and without mitochondrial presequence), has led to its increased enzyme activity. Further, it was demonstrated that overexpression of full-length POS5 has improved squalene synthesis in cytosol. Finally, when tHMG1 and full-length POS5 were co-overexpressed there was a net 27.5-fold increase in squalene when compared to control strain. These results suggest novel strategies to increase squalene accumulation in S. cerevisiae.
Collapse
Affiliation(s)
- Kalaivani Paramasivan
- Microbiology and Fermentation Technology Department, CSIR-Central Food Technological Research Institute , Mysore, India
- Academy of Scientific and Innovative Research , Mysore, New Delhi, India
| | - Sarma Mutturi
- Microbiology and Fermentation Technology Department, CSIR-Central Food Technological Research Institute , Mysore, India
- Academy of Scientific and Innovative Research , Mysore, New Delhi, India
| |
Collapse
|
68
|
Influence of genetic background of engineered xylose-fermenting industrial Saccharomyces cerevisiae strains for ethanol production from lignocellulosic hydrolysates. J Ind Microbiol Biotechnol 2017; 44:1575-1588. [PMID: 28891041 DOI: 10.1007/s10295-017-1979-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 09/05/2017] [Indexed: 10/18/2022]
Abstract
An industrial ethanol-producing Saccharomyces cerevisiae strain with genes of fungal oxido-reductive pathway needed for xylose fermentation integrated into its genome (YRH1415) was used to obtain haploids and diploid isogenic strains. The isogenic strains were more effective in metabolizing xylose than YRH1415 strain and able to co-ferment glucose and xylose in the presence of high concentrations of inhibitors resulting from the hydrolysis of lignocellulosic biomass (switchgrass). The rate of xylose consumption did not appear to be affected by the ploidy of strains or the presence of two copies of the xylose fermentation genes but by heterozygosity of alleles for xylose metabolism in YRH1415. Furthermore, inhibitor tolerance was influenced by the heterozygous genome of the industrial strain, which also showed a marked influenced on tolerance to increasing concentrations of toxic compounds, such as furfural. In this work, selection of haploid derivatives was found to be a useful strategy to develop efficient xylose-fermenting industrial yeast strains.
Collapse
|
69
|
Novy V, Wang R, Westman JO, Franzén CJ, Nidetzky B. Saccharomyces cerevisiae strain comparison in glucose-xylose fermentations on defined substrates and in high-gravity SSCF: convergence in strain performance despite differences in genetic and evolutionary engineering history. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:205. [PMID: 28878820 PMCID: PMC5584037 DOI: 10.1186/s13068-017-0887-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/12/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The most advanced strains of xylose-fermenting Saccharomyces cerevisiae still utilize xylose far less efficiently than glucose, despite the extensive metabolic and evolutionary engineering applied in their development. Systematic comparison of strains across literature is difficult due to widely varying conditions used for determining key physiological parameters. Here, we evaluate an industrial and a laboratory S. cerevisiae strain, which has the assimilation of xylose via xylitol in common, but differ fundamentally in the history of their adaptive laboratory evolution development, and in the cofactor specificity of the xylose reductase (XR) and xylitol dehydrogenase (XDH). RESULTS In xylose and mixed glucose-xylose shaken bottle fermentations, with and without addition of inhibitor-rich wheat straw hydrolyzate, the specific xylose uptake rate of KE6-12.A (0.27-1.08 g gCDW-1 h-1) was 1.1 to twofold higher than that of IBB10B05 (0.10-0.82 g gCDW-1 h-1). KE6-12.A further showed a 1.1 to ninefold higher glycerol yield (0.08-0.15 g g-1) than IBB10B05 (0.01-0.09 g g-1). However, the ethanol yield (0.30-0.40 g g-1), xylitol yield (0.08-0.26 g g-1), and maximum specific growth rate (0.04-0.27 h-1) were in close range for both strains. The robustness of flocculating variants of KE6-12.A (KE-Flow) and IBB10B05 (B-Flow) was analyzed in high-gravity simultaneous saccharification and co-fermentation. As in shaken bottles, KE-Flow showed faster xylose conversion and higher glycerol formation than B-Flow, but final ethanol titres (61 g L-1) and cell viability were again comparable for both strains. CONCLUSIONS Individual specific traits, elicited by the engineering strategy, can affect global physiological parameters of S. cerevisiae in different and, sometimes, unpredictable ways. The industrial strain background and prolonged evolution history in KE6-12.A improved the specific xylose uptake rate more substantially than the superior XR, XDH, and xylulokinase activities were able to elicit in IBB10B05. Use of an engineered XR/XDH pathway in IBB10B05 resulted in a lower glycerol rather than a lower xylitol yield. However, the strain development programs were remarkably convergent in terms of the achieved overall strain performance. This highlights the importance of comparative strain evaluation to advance the engineering strategies for next-generation S. cerevisiae strain development.
Collapse
Affiliation(s)
- Vera Novy
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Graz, Austria
| | - Ruifei Wang
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Johan O Westman
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Carl Johan Franzén
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Graz, Austria
| |
Collapse
|
70
|
Liu G, Chen Y, Færgeman NJ, Nielsen J. Elimination of the last reactions in ergosterol biosynthesis alters the resistance of Saccharomyces cerevisiae to multiple stresses. FEMS Yeast Res 2017; 17:4082736. [DOI: 10.1093/femsyr/fox063] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/09/2017] [Indexed: 01/25/2023] Open
|
71
|
Bonturi N, Crucello A, Viana AJC, Miranda EA. Microbial oil production in sugarcane bagasse hemicellulosic hydrolysate without nutrient supplementation by a Rhodosporidium toruloides adapted strain. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.03.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
72
|
Deparis Q, Claes A, Foulquié-Moreno MR, Thevelein JM. Engineering tolerance to industrially relevant stress factors in yeast cell factories. FEMS Yeast Res 2017; 17:3861662. [PMID: 28586408 PMCID: PMC5812522 DOI: 10.1093/femsyr/fox036] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/04/2017] [Indexed: 01/01/2023] Open
Abstract
The main focus in development of yeast cell factories has generally been on establishing optimal activity of heterologous pathways and further metabolic engineering of the host strain to maximize product yield and titer. Adequate stress tolerance of the host strain has turned out to be another major challenge for obtaining economically viable performance in industrial production. Although general robustness is a universal requirement for industrial microorganisms, production of novel compounds using artificial metabolic pathways presents additional challenges. Many of the bio-based compounds desirable for production by cell factories are highly toxic to the host cells in the titers required for economic viability. Artificial metabolic pathways also turn out to be much more sensitive to stress factors than endogenous pathways, likely because regulation of the latter has been optimized in evolution in myriads of environmental conditions. We discuss different environmental and metabolic stress factors with high relevance for industrial utilization of yeast cell factories and the experimental approaches used to engineer higher stress tolerance. Improving stress tolerance in a predictable manner in yeast cell factories should facilitate their widespread utilization in the bio-based economy and extend the range of products successfully produced in large scale in a sustainable and economically profitable way.
Collapse
Affiliation(s)
- Quinten Deparis
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Arne Claes
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Maria R. Foulquié-Moreno
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Johan M. Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| |
Collapse
|
73
|
|
74
|
Wang S, He Z, Yuan Q. Xylose enhances furfural tolerance in Candida tropicalis by improving NADH recycle. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2016.09.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
75
|
Enhanced ethanol fermentation by engineered Saccharomyces cerevisiae strains with high spermidine contents. Bioprocess Biosyst Eng 2017; 40:683-691. [DOI: 10.1007/s00449-016-1733-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/26/2016] [Indexed: 01/03/2023]
|
76
|
Moreno AD, Alvira P, Ibarra D, Tomás-Pejó E. Production of Ethanol from Lignocellulosic Biomass. PRODUCTION OF PLATFORM CHEMICALS FROM SUSTAINABLE RESOURCES 2017. [DOI: 10.1007/978-981-10-4172-3_12] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
77
|
Lis P, Jurkiewicz P, Cal-Bąkowska M, Ko YH, Pedersen PL, Goffeau A, Ułaszewski S. Screening the yeast genome for energetic metabolism pathways involved in a phenotypic response to the anti-cancer agent 3-bromopyruvate. Oncotarget 2016; 7:10153-73. [PMID: 26862728 PMCID: PMC4891110 DOI: 10.18632/oncotarget.7174] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/23/2016] [Indexed: 01/19/2023] Open
Abstract
In this study the detailed characteristic of the anti-cancer agent 3-bromopyruvate (3-BP) activity in the yeast Saccharomyces cerevisiae model is described, with the emphasis on its influence on energetic metabolism of the cell. It shows that 3-BP toxicity in yeast is strain-dependent and influenced by the glucose-repression system. Its toxic effect is mainly due to the rapid depletion of intracellular ATP. Moreover, lack of the Whi2p phosphatase results in strongly increased sensitivity of yeast cells to 3-BP, possibly due to the non-functional system of mitophagy of damaged mitochondria through the Ras-cAMP-PKA pathway. Single deletions of genes encoding glycolytic enzymes, the TCA cycle enzymes and mitochondrial carriers result in multiple effects after 3-BP treatment. However, it can be concluded that activity of the pentose phosphate pathway is necessary to prevent the toxicity of 3-BP, probably due to the fact that large amounts of NADPH are produced by this pathway, ensuring the reducing force needed for glutathione reduction, crucial to cope with the oxidative stress. Moreover, single deletions of genes encoding the TCA cycle enzymes and mitochondrial carriers generally cause sensitivity to 3-BP, while totally inactive mitochondrial respiration in the rho0 mutant resulted in increased resistance to 3-BP.
Collapse
Affiliation(s)
- Paweł Lis
- Department of Genetics, Institute of Genetics and Microbiology, University of Wrocław, Wrocław, Poland
| | - Paweł Jurkiewicz
- Department of Genetics, Institute of Genetics and Microbiology, University of Wrocław, Wrocław, Poland
| | - Magdalena Cal-Bąkowska
- Department of Genetics, Institute of Genetics and Microbiology, University of Wrocław, Wrocław, Poland
| | - Young H Ko
- KoDiscovery LLC, UM BioPark, Innovation Center, Baltimore, MD, USA
| | - Peter L Pedersen
- Departments of Biological Chemistry and Oncology, Sydney Kimmel Comprehensive Cancer Center and Center for Obesity Research and Metabolism, John Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andre Goffeau
- Unité de Biochimie Physiologique, Institut des Sciences de la Vie, Université Catholique de Louvain-la-Neuve, Louvain-la-Neuve, Belgium
| | - Stanisław Ułaszewski
- Department of Genetics, Institute of Genetics and Microbiology, University of Wrocław, Wrocław, Poland
| |
Collapse
|
78
|
Jung YH, Kim S, Yang J, Seo JH, Kim KH. Intracellular metabolite profiling of Saccharomyces cerevisiae evolved under furfural. Microb Biotechnol 2016; 10:395-404. [PMID: 27928897 PMCID: PMC5328829 DOI: 10.1111/1751-7915.12465] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 12/21/2022] Open
Abstract
Furfural, one of the most common inhibitors in pre‐treatment hydrolysates, reduces the cell growth and ethanol production of yeast. Evolutionary engineering has been used as a selection scheme to obtain yeast strains that exhibit furfural tolerance. However, the response of Saccharomyces cerevisiae to furfural at the metabolite level during evolution remains unknown. In this study, evolutionary engineering and metabolomic analyses were applied to determine the effects of furfural on yeasts and their metabolic response to continuous exposure to furfural. After 50 serial transfers of cultures in the presence of furfural, the evolved strains acquired the ability to stably manage its physiological status under the furfural stress. A total of 98 metabolites were identified, and their abundance profiles implied that yeast metabolism was globally regulated. Under the furfural stress, stress‐protective molecules and cofactor‐related mechanisms were mainly induced in the parental strain. However, during evolution under the furfural stress, S. cerevisiae underwent global metabolic allocations to quickly overcome the stress, particularly by maintaining higher levels of metabolites related to energy generation, cofactor regeneration and recovery from cellular damage. Mapping the mechanisms of furfural tolerance conferred by evolutionary engineering in the present study will be led to rational design of metabolically engineered yeasts.
Collapse
Affiliation(s)
- Young Hoon Jung
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, 41566, South Korea
| | - Sooah Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Jungwoo Yang
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Jin-Ho Seo
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul, 08826, South Korea
| | - Kyoung Heon Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| |
Collapse
|
79
|
Production of valuable compounds by molds and yeasts. J Antibiot (Tokyo) 2016; 70:347-360. [PMID: 27731337 PMCID: PMC7094691 DOI: 10.1038/ja.2016.121] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/31/2016] [Accepted: 09/01/2016] [Indexed: 11/30/2022]
Abstract
We are pleased to dedicate this paper to Dr Julian E Davies. Julian is a giant among microbial biochemists. He began his professional career as an organic chemistry PhD student at Nottingham University, moved on to a postdoctoral fellowship at Columbia University, then became a lecturer at the University of Manchester, followed by a fellowship in microbial biochemistry at Harvard Medical School. In 1965, he studied genetics at the Pasteur Institute, and 2 years later joined the University of Wisconsin in the Department of Biochemistry. He later became part of Biogen as Research Director and then President. After Biogen, Julian became Chair of the Department of Microbiology at the University of British Columbia in Vancouver, Canada, where he has contributed in a major way to the reputation of this department for many years. He also served as an Adjunct Professor at the University of Geneva. Among Julian’s areas of study and accomplishment are fungal toxins including α-sarcin, chemical synthesis of triterpenes, mode of action of streptomycin and other aminoglycoside antibiotics, biochemical mechanisms of antibiotic resistance in clinical isolates of bacteria harboring resistance plasmids, their origins and evolution, secondary metabolism of microorganisms, structure and function of bacterial ribosomes, antibiotic resistance mutations in yeast ribosomes, cloning of resistance genes from an antibiotic-producing microbe, gene cloning for industrial purposes, engineering of herbicide resistance in useful crops, bleomycin-resistance gene in clinical isolates of Staphylococcus aureus and many other topics. He has been an excellent teacher, lecturing in both English and French around the world, and has organized international courses. Julian has also served on the NIH study sections, as Editor for several international journals, and was one of the founders of the journal Plasmid. We expect the impact of Julian’s accomplishments to continue into the future.
Collapse
|
80
|
Sardi M, Rovinskiy N, Zhang Y, Gasch AP. Leveraging Genetic-Background Effects in Saccharomyces cerevisiae To Improve Lignocellulosic Hydrolysate Tolerance. Appl Environ Microbiol 2016; 82:5838-49. [PMID: 27451446 PMCID: PMC5038035 DOI: 10.1128/aem.01603-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/14/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A major obstacle to sustainable lignocellulosic biofuel production is microbe inhibition by the combinatorial stresses in pretreated plant hydrolysate. Chemical biomass pretreatment releases a suite of toxins that interact with other stressors, including high osmolarity and temperature, which together can have poorly understood synergistic effects on cells. Improving tolerance in industrial strains has been hindered, in part because the mechanisms of tolerance reported in the literature often fail to recapitulate in other strain backgrounds. Here, we explored and then exploited variations in stress tolerance, toxin-induced transcriptomic responses, and fitness effects of gene overexpression in different Saccharomyces cerevisiae (yeast) strains to identify genes and processes linked to tolerance of hydrolysate stressors. Using six different S. cerevisiae strains that together maximized phenotypic and genetic diversity, first we explored transcriptomic differences between resistant and sensitive strains to identify common and strain-specific responses. This comparative analysis implicated primary cellular targets of hydrolysate toxins, secondary effects of defective defense strategies, and mechanisms of tolerance. Dissecting the responses to individual hydrolysate components across strains pointed to synergistic interactions between osmolarity, pH, hydrolysate toxins, and nutrient composition. By characterizing the effects of high-copy gene overexpression in three different strains, we revealed the breadth of the background-specific effects of gene fitness contributions in synthetic hydrolysate. Our approach identified new genes for engineering improved stress tolerance in diverse strains while illuminating the effects of genetic background on molecular mechanisms. IMPORTANCE Recent studies on natural variation within Saccharomyces cerevisiae have uncovered substantial phenotypic diversity. Here, we took advantage of this diversity, using it as a tool to infer the effects of combinatorial stress found in lignocellulosic hydrolysate. By comparing sensitive and tolerant strains, we implicated primary cellular targets of hydrolysate toxins and elucidated the physiological states of cells when exposed to this stress. We also explored the strain-specific effects of gene overexpression to further identify strain-specific responses to hydrolysate stresses and to identify genes that improve hydrolysate tolerance independent of strain background. This study underscores the importance of studying multiple strains to understand the effects of hydrolysate stress and provides a method to find genes that improve tolerance across strain backgrounds.
Collapse
Affiliation(s)
- Maria Sardi
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA Microbiology Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Nikolay Rovinskiy
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Yaoping Zhang
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Audrey P Gasch
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
81
|
Guo W, Chen Y, Wei N, Feng X. Investigate the Metabolic Reprogramming of Saccharomyces cerevisiae for Enhanced Resistance to Mixed Fermentation Inhibitors via 13C Metabolic Flux Analysis. PLoS One 2016; 11:e0161448. [PMID: 27532329 PMCID: PMC4988770 DOI: 10.1371/journal.pone.0161448] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/07/2016] [Indexed: 11/18/2022] Open
Abstract
The fermentation inhibitors from the pretreatment of lignocellulosic materials, e.g., acetic acid and furfural, are notorious due to their negative effects on the cell growth and chemical production. However, the metabolic reprogramming of the cells under these stress conditions, especially metabolic response for resistance to mixed inhibitors, has not been systematically investigated and remains mysterious. Therefore, in this study, 13C metabolic flux analysis (13C-MFA), a powerful tool to elucidate the intracellular carbon flux distributions, has been applied to two Saccharomyces cerevisiae strains with different tolerances to the inhibitors under acetic acid, furfural, and mixed (i.e., acetic acid and furfural) stress conditions to unravel the key metabolic responses. By analyzing the intracellular carbon fluxes as well as the energy and cofactor utilization under different conditions, we uncovered varied metabolic responses to different inhibitors. Under acetate stress, ATP and NADH production was slightly impaired, while NADPH tended towards overproduction. Under furfural stress, ATP and cofactors (including both NADH and NADPH) tended to be overproduced. However, under dual-stress condition, production of ATP and cofactors was severely impaired due to synergistic stress caused by the simultaneous addition of two fermentation inhibitors. Such phenomenon indicated the pivotal role of the energy and cofactor utilization in resisting the mixed inhibitors of acetic acid and furfural. Based on the discoveries, valuable insights are provided to improve the tolerance of S. cerevisiae strain and further enhance lignocellulosic fermentation.
Collapse
Affiliation(s)
- Weihua Guo
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States of America
| | - Yingying Chen
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, United States of America
| | - Na Wei
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, United States of America
- * E-mail: (NW); (XF)
| | - Xueyang Feng
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States of America
- * E-mail: (NW); (XF)
| |
Collapse
|
82
|
Christopher M, Anusree M, Mathew AK, Nampoothiri KM, Sukumaran RK, Pandey A. Detoxification of acidic biorefinery waste liquor for production of high value amino acid. BIORESOURCE TECHNOLOGY 2016; 213:270-275. [PMID: 26996259 DOI: 10.1016/j.biortech.2016.03.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 03/08/2016] [Accepted: 03/10/2016] [Indexed: 05/14/2023]
Abstract
The current study evaluates the detoxification of acid pretreatment liquor (APL) using adsorbent (ADS 400 & ADS 800) or ion-exchange (A-27MP & A-72MP) resins and its potential for amino acid production. The APL is generated as a by-product from the pretreatment of lignocellulosic biomass and is rich monomeric sugars as well as sugar degradation products (fermentation inhibitors) such as furfural and hydroxymethyl furfural (HMF). Of the four resins compared, ADS 800 removed approximately 85% and 60% of furfural and HMF, respectively. ADS 800 could be reused for up to six cycles after regeneration without losing its adsorption properties. The study was further extended by assessing the fermentability of detoxified APL for l-lysine production using wild and mutant strains of Corynebacterium glutamicum. The detoxified APL was superior to APL for l-lysine production.
Collapse
Affiliation(s)
- Meera Christopher
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India
| | - Murali Anusree
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India
| | - Anil K Mathew
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India.
| | - K Madhavan Nampoothiri
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India
| | - Rajeev Kumar Sukumaran
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India
| | - Ashok Pandey
- Centre for Biofuels and Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019, India
| |
Collapse
|
83
|
Kim IS, Kim YS, Kim YH, Park AK, Kim HW, Lee JH, Yoon HS. Potential Application of the Oryza sativa Monodehydroascorbate Reductase Gene (OsMDHAR) to Improve the Stress Tolerance and Fermentative Capacity of Saccharomyces cerevisiae. PLoS One 2016; 11:e0158841. [PMID: 27392090 PMCID: PMC4938589 DOI: 10.1371/journal.pone.0158841] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/22/2016] [Indexed: 02/06/2023] Open
Abstract
Monodehydroascorbate reductase (MDHAR; EC 1.6.5.4) is an important enzyme for ascorbate recycling. To examine whether heterologous expression of MDHAR from Oryza sativa (OsMDHAR) can prevent the deleterious effects of unfavorable growth conditions, we constructed a transgenic yeast strain harboring a recombinant plasmid carrying OsMDHAR (p426GPD::OsMDHAR). OsMDHAR-expressing yeast cells displayed enhanced tolerance to hydrogen peroxide by maintaining redox homoeostasis, proteostasis, and the ascorbate (AsA)-like pool following the accumulation of antioxidant enzymes and molecules, metabolic enzymes, and molecular chaperones and their cofactors, compared to wild-type (WT) cells carrying vector alone. The addition of exogenous AsA or its analogue isoascorbic acid increased the viability of WT and ara2Δ cells under oxidative stress. Furthermore, the survival of OsMDHAR-expressing cells was greater than that of WT cells when cells at mid-log growth phase were exposed to high concentrations of ethanol. High OsMDHAR expression also improved the fermentative capacity of the yeast during glucose-based batch fermentation at a standard cultivation temperature (30°C). The alcohol yield of OsMDHAR-expressing transgenic yeast during fermentation was approximately 25% (0.18 g·g-1) higher than that of WT yeast. Accordingly, OsMDHAR-expressing transgenic yeast showed prolonged survival during the environmental stresses produced during fermentation. These results suggest that heterologous OsMDHAR expression increases tolerance to reactive oxygen species-induced oxidative stress by improving cellular redox homeostasis and improves survival during fermentation, which enhances fermentative capacity.
Collapse
Affiliation(s)
- Il-Sup Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
- * E-mail: (I-SK); (H-SY)
| | - Young-Saeng Kim
- Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Yul-Ho Kim
- Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration, Pyeongchang, Republic of Korea
| | - Ae-Kyung Park
- Division of Polar Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Han-Woo Kim
- Division of Polar Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Jun-Hyuk Lee
- Division of Polar Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Ho-Sung Yoon
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
- * E-mail: (I-SK); (H-SY)
| |
Collapse
|
84
|
Genetic Enhancement of Saccharomyces cerevisiae for First and Second Generation Ethanol Production. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1201/b19347-11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
85
|
Papapetridis I, van Dijk M, Dobbe APA, Metz B, Pronk JT, van Maris AJA. Improving ethanol yield in acetate-reducing Saccharomyces cerevisiae by cofactor engineering of 6-phosphogluconate dehydrogenase and deletion of ALD6. Microb Cell Fact 2016; 15:67. [PMID: 27118055 PMCID: PMC5574463 DOI: 10.1186/s12934-016-0465-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/13/2016] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Acetic acid, an inhibitor of sugar fermentation by yeast, is invariably present in lignocellulosic hydrolysates which are used or considered as feedstocks for yeast-based bioethanol production. Saccharomyces cerevisiae strains have been constructed, in which anaerobic reduction of acetic acid to ethanol replaces glycerol formation as a mechanism for reoxidizing NADH formed in biosynthesis. An increase in the amount of acetate that can be reduced to ethanol should further decrease acetic acid concentrations and enable higher ethanol yields in industrial processes based on lignocellulosic feedstocks. The stoichiometric requirement of acetate reduction for NADH implies that increased generation of NADH in cytosolic biosynthetic reactions should enhance acetate consumption. RESULTS Replacement of the native NADP(+)-dependent 6-phosphogluconate dehydrogenase in S. cerevisiae by a prokaryotic NAD(+)-dependent enzyme resulted in increased cytosolic NADH formation, as demonstrated by a ca. 15% increase in the glycerol yield on glucose in anaerobic cultures. Additional deletion of ALD6, which encodes an NADP(+)-dependent acetaldehyde dehydrogenase, led to a 39% increase in the glycerol yield compared to a non-engineered strain. Subsequent replacement of glycerol formation by an acetate reduction pathway resulted in a 44% increase of acetate consumption per amount of biomass formed, as compared to an engineered, acetate-reducing strain that expressed the native 6-phosphogluconate dehydrogenase and ALD6. Compared to a non-acetate reducing reference strain under the same conditions, this resulted in a ca. 13% increase in the ethanol yield on glucose. CONCLUSIONS The combination of NAD(+)-dependent 6-phosphogluconate dehydrogenase expression and deletion of ALD6 resulted in a marked increase in the amount of acetate that was consumed in these proof-of-principle experiments, and this concept is ready for further testing in industrial strains as well as in hydrolysates. Altering the cofactor specificity of the oxidative branch of the pentose-phosphate pathway in S. cerevisiae can also be used to increase glycerol production in wine fermentation and to improve NADH generation and/or generation of precursors derived from the pentose-phosphate pathway in other industrial applications of this yeast.
Collapse
Affiliation(s)
- Ioannis Papapetridis
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Marlous van Dijk
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Arthur PA Dobbe
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Benjamin Metz
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Jack T. Pronk
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Antonius J. A. van Maris
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| |
Collapse
|
86
|
Jayakody LN, Ferdouse J, Hayashi N, Kitagaki H. Identification and detoxification of glycolaldehyde, an unattended bioethanol fermentation inhibitor. Crit Rev Biotechnol 2016; 37:177-189. [PMID: 26953525 DOI: 10.3109/07388551.2015.1128877] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Although there have been approximately 60 chemical compounds identified as potent fermentation inhibitors in lignocellulose hydrolysate, our research group recently discovered glycolaldehyde as a key fermentation inhibitor during second generation biofuel production. Accordingly, we have developed a yeast S. cerevisiae strain exhibiting tolerance to glycolaldehyde. During this glycolaldehyde study, we established novel approaches for rational engineering of inhibitor-tolerant S. cerevisiae strains, including engineering redox cofactors and engineering the SUMOylation pathway. These new technical dimensions provide a novel platform for engineering S. cerevisiae strains to overcome one of the key barriers for industrialization of lignocellulosic ethanol production. As such, this review discusses novel biochemical insight of glycolaldehyde in the context of the biofuel industry.
Collapse
Affiliation(s)
- Lahiru N Jayakody
- a Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana , IL , USA.,b Department of Biochemistry and Applied Biosciences United Graduate School of Agricultural Sciences , Kagoshima University , Kagoshima , Japan , and
| | - Jannatul Ferdouse
- c Department of Environmental Sciences Faculty of Agriculture , Saga University , Saga , Japan
| | - Nobuyuki Hayashi
- c Department of Environmental Sciences Faculty of Agriculture , Saga University , Saga , Japan
| | - Hiroshi Kitagaki
- b Department of Biochemistry and Applied Biosciences United Graduate School of Agricultural Sciences , Kagoshima University , Kagoshima , Japan , and.,c Department of Environmental Sciences Faculty of Agriculture , Saga University , Saga , Japan
| |
Collapse
|
87
|
Thompson OA, Hawkins GM, Gorsich SW, Doran-Peterson J. Phenotypic characterization and comparative transcriptomics of evolved Saccharomyces cerevisiae strains with improved tolerance to lignocellulosic derived inhibitors. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:200. [PMID: 27679668 PMCID: PMC5029107 DOI: 10.1186/s13068-016-0614-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/07/2016] [Indexed: 05/15/2023]
Abstract
BACKGROUND Lignocellulosic biomass continues to be investigated as a viable source for bioethanol production. However, the pretreatment process generates inhibitory compounds that impair the growth and fermentation performance of microorganisms such as Saccharomyces cerevisiae. Pinewood specifically has been shown to be challenging in obtaining industrially relevant ethanol titers. An industrial S. cerevisiae strain was subjected to directed evolution and adaptation in pretreated pine biomass and resultant strains, GHP1 and GHP4, exhibited improved growth and fermentative ability on pretreated pine in the presence of related inhibitory compounds. A comparative transcriptomic approach was applied to identify and characterize differences in phenotypic stability of evolved strains. RESULTS Evolved strains displayed different fermentative capabilities with pretreated pine that appear to be influenced by the addition or absence of 13 inhibitory compounds during pre-culturing. GHP4 performance was consistent independent of culturing conditions, while GHP1 performance was dependent on culturing with inhibitors. Comparative transcriptomics revealed 52 genes potentially associated with stress responses to multiple inhibitors simultaneously. Fluorescence microscopy revealed improved cellular integrity of both strains with mitochondria exhibiting resistance to the damaging effects of inhibitors in contrast to the parent. CONCLUSIONS Multiple potentially novel genetic targets have been discovered for understanding stress tolerance through the characterization of our evolved strains. This study specifically examines the synergistic effects of multiple inhibitors and identified targets will guide future studies in remediating effects of inhibitors and further development of robust yeast strains for multiple industrial applications.
Collapse
Affiliation(s)
| | - Gary M. Hawkins
- Department of Microbiology, University of Georgia, Athens, GA 30602 USA
| | - Steven W. Gorsich
- Department of Biology, Central Michigan University, Mount Pleasant, MI 48859 USA
| | | |
Collapse
|
88
|
Hasunuma T, Sakamoto T, Kondo A. Inverse metabolic engineering based on transient acclimation of yeast improves acid-containing xylose fermentation and tolerance to formic and acetic acids. Appl Microbiol Biotechnol 2016; 100:1027-38. [PMID: 26521247 DOI: 10.1007/s00253-015-7094-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/28/2015] [Accepted: 10/11/2015] [Indexed: 02/02/2023]
Abstract
Improving the production of ethanol from xylose is an important goal in metabolic engineering of Saccharomyces cerevisiae. Furthermore, S. cerevisiae must produce ethanol in the presence of weak acids (formate and acetate) generated during pre-treatment of lignocellulosic biomass. In this study, weak acid-containing xylose fermentation was significantly improved using cells that were acclimated to the weak acids during pre-cultivation. Transcriptome analyses showed that levels of transcripts for transcriptional/translational machinery-related genes (RTC3 and ANB1) were enhanced by formate and acetate acclimation. Recombinant yeast strains overexpressing RTC3 and ANB1 demonstrated improved ethanol production from xylose in the presence of the weak acids, along with improved tolerance to the acids. Novel metabolic engineering strategy based on the combination of short-term acclimation and system-wide analysis was developed, which can develop stress-tolerant strains in a short period of time, although conventional evolutionary engineering approach has required long periods of time to isolate inhibitor-adapted strains.
Collapse
Affiliation(s)
- Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Takatoshi Sakamoto
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan.
- Biomass Engineering Program, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
| |
Collapse
|
89
|
Chen Y, Sheng J, Jiang T, Stevens J, Feng X, Wei N. Transcriptional profiling reveals molecular basis and novel genetic targets for improved resistance to multiple fermentation inhibitors in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:9. [PMID: 26766964 PMCID: PMC4710983 DOI: 10.1186/s13068-015-0418-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 12/15/2015] [Indexed: 05/07/2023]
Abstract
BACKGROUND Lignocellulosic biomass is a promising source of renewable biofuels. However, pretreatment of lignocellulosic biomass generates fermentation inhibitors that adversely affect the growth of industrial microorganisms such as Saccharomyces cerevisiae and prevent economic production of lignocellulosic biofuels. A critical challenge on developing S. cerevisiae with improved inhibitor resistance lies in incomplete understanding of molecular basis for inhibitor stress response and limited information on effective genetic targets for increasing yeast resistance to mixed fermentation inhibitors. In this study, we applied comparative transcriptomic analysis to determine the molecular basis for acetic acid and/or furfural resistance in S. cerevisiae. RESULTS We recently developed a yeast strain YC1 with superior resistance to acetic acid, furfural, and their mixture through inverse metabolic engineering. In this study, we first determined transcriptional changes through RNA sequencing in YC1 versus the wild-type strain S-C1 under three different inhibitor conditions, including acetic acid alone, furfural alone, and mixture of acetic acid and furfural. The genes associated with stress responses of S. cerevisiae to single and mixed inhibitors were revealed. Specifically, we identified 184 consensus genes that were differentially regulated in response to the distinct inhibitor resistance between YC1 and S-C1. Bioinformatic analysis next revealed key transcription factors (TFs) that regulate these consensus genes. The top TFs identified, Sfp1p and Ace2p, were experimentally tested as overexpression targets for strain optimization. Overexpression of the SFP1 gene improved specific ethanol productivity by nearly four times, while overexpression of the ACE2 gene enhanced the rate by three times in the presence of acetic acid and furfural. Overexpression of SFP1 gene in the resistant strain YC1 further resulted in 42 % increase in ethanol productivity in the presence of acetic acid and furfural, suggesting the effect of Sfp1p in optimizing the yeast strain for improved tolerance to mixed fermentation inhibitor. CONCLUSIONS Transcriptional regulation underlying yeast resistance to acetic acid and furfural was determined. Two transcription factors, Sfp1p and Ace2p, were uncovered for the first time for their functions in improving yeast resistance to mixed fermentation inhibitors. The study demonstrated an omics-guided metabolic engineering framework, which could be developed as a promising strategy to improve complex microbial phenotypes.
Collapse
Affiliation(s)
- Yingying Chen
- />Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 106E Cushing Hall of Engineering, Notre Dame, South Bend, IN 46556 USA
| | - Jiayuan Sheng
- />Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA USA
| | - Tao Jiang
- />Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA USA
| | - Joseph Stevens
- />Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA USA
| | - Xueyang Feng
- />Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA USA
| | - Na Wei
- />Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 106E Cushing Hall of Engineering, Notre Dame, South Bend, IN 46556 USA
| |
Collapse
|
90
|
Wang S, Cheng G, Joshua C, He Z, Sun X, Li R, Liu L, Yuan Q. Furfural tolerance and detoxification mechanism in Candida tropicalis. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:250. [PMID: 27891177 PMCID: PMC5116146 DOI: 10.1186/s13068-016-0668-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/15/2016] [Indexed: 05/02/2023]
Abstract
BACKGROUND Current biomass pretreatment by hydrothermal treatment (including acid hydrolysis, steam explosion, and high-temperature steaming) and ionic liquids generally generate inhibitors to the following fermentation process. Furfural is one of the typical inhibitors generated in hydrothermal treatment of biomass. Furfural could inhibit cell growth rate and decrease biofuel productivity of microbes. Candida tropicalis is a promising microbe for the production of biofuels and value-added chemicals using hemicellulose hydrolysate as carbon source. In this study, C. tropicalis showed a comparable ability of furfural tolerance during fermentation. We investigated the mechanism of C. tropicalis's robust tolerance to furfural and relevant metabolic responses to obtain more information for metabolic engineering of microbes for efficient lignocellulose fermentation. RESULTS Candida tropicalis showed comparable intrinsic tolerance to furfural and a fast rate of furfural detoxification. C. tropicalis's half maximal inhibitory concentration for furfural with xylose as the sole carbon source was 3.69 g/L, which was higher than that of most wild-type microbes reported in the literature to our knowledge. Even though furfural prolonged the lag phase of C. tropicalis, the final biomass in the groups treated with 1 g/L furfural was slightly greater than that in the control groups. By real-time PCR analysis, we found that the expression of ADH1 in C. tropicalis (ctADH1) was induced by furfural and repressed by ethanol after furfural depletion. The expression of ctADH1 could be regulated by both furfural and ethanol. After the disruption of gene ctADH1, we found that C. tropicalis's furfural tolerance was weakened. To further confirm the function of ctADH1 and enhance Escherichia coli's furfural tolerance, ctADH1 was overexpressed in E. coli BL21 (DE3). The rate of furfural degradation in E. coli BL21 (DE3) with pET-ADH1 (high-copy plasmid) and pCS-ADH1 (medium-copy plasmid) was increased by 1.59-fold and 1.28-fold, respectively. CONCLUSIONS Candida tropicalis was a robust strain with intrinsic tolerance to inhibitor furfural. The mechanism of furfural detoxification and metabolic responses were identified by multiple analyses. Alcohol dehydrogenase 1 was confirmed to be responsible for furfural detoxification. C. tropicalis showed a complex regulation system during furfural detoxification to minimize adverse effects caused by furfural. Furthermore, the mechanism we uncovered in this work was successfully applied to enhance E. coli's furfural tolerance by heterologous expression of ctADH1. The study provides deeper insights into strain modification for biofuel production by efficient lignocellulose fermentation.
Collapse
Affiliation(s)
- Shizeng Wang
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Gang Cheng
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Chijioke Joshua
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608 USA
| | - Zijun He
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Ruimin Li
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Lexuan Liu
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| | - Qipeng Yuan
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, West Room 314, Science and Technology Building, No. 15 North Third Ring East Road, Chaoyang District, Beijing, 100029 People’s Republic of China
| |
Collapse
|
91
|
Combinatorial application of two aldehyde oxidoreductases on isobutanol production in the presence of furfural. ACTA ACUST UNITED AC 2016; 43:37-44. [DOI: 10.1007/s10295-015-1718-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/29/2015] [Indexed: 11/26/2022]
Abstract
Abstract
Furfural is a toxic by-product formulated from pretreatment processes of lignocellulosic biomass. In order to utilize the lignocellulosic biomass on isobutanol production, inhibitory effect of the furfural on isobutanol production was investigated and combinatorial application of two oxidoreductases, FucO and YqhD, was suggested as an alternative strategy. Furfural decreased cell growth and isobutanol production when only YqhD or FucO was employed as an isobutyraldehyde oxidoreductase. However, combinatorial overexpression of FucO and YqhD could overcome the inhibitory effect of furfural giving higher isobutanol production by 110 % compared with overexpression of YqhD. The combinatorial oxidoreductases increased furfural detoxification rate 2.1-fold and also accelerated glucose consumption 1.4-fold. When it compares to another known system increasing furfural tolerance, membrane-bound transhydrogenase (pntAB), the combinatorial aldehyde oxidoreductases were better on cell growth and production. Thus, to control oxidoreductases is important to produce isobutanol using furfural-containing biomass and the combinatorial overexpression of FucO and YqhD can be an alternative strategy.
Collapse
|
92
|
Caspeta L, Castillo T, Nielsen J. Modifying Yeast Tolerance to Inhibitory Conditions of Ethanol Production Processes. Front Bioeng Biotechnol 2015; 3:184. [PMID: 26618154 PMCID: PMC4641163 DOI: 10.3389/fbioe.2015.00184] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/28/2015] [Indexed: 11/17/2022] Open
Abstract
Saccharomyces cerevisiae strains having a broad range of substrate utilization, rapid substrate consumption, and conversion to ethanol, as well as good tolerance to inhibitory conditions are ideal for cost-competitive ethanol production from lignocellulose. A major drawback to directly design S. cerevisiae tolerance to inhibitory conditions of lignocellulosic ethanol production processes is the lack of knowledge about basic aspects of its cellular signaling network in response to stress. Here, we highlight the inhibitory conditions found in ethanol production processes, the targeted cellular functions, the key contributions of integrated -omics analysis to reveal cellular stress responses according to these inhibitors, and current status on design-based engineering of tolerant and efficient S. cerevisiae strains for ethanol production from lignocellulose.
Collapse
Affiliation(s)
- Luis Caspeta
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos , Cuernavaca , Mexico
| | - Tania Castillo
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos , Cuernavaca , Mexico
| | - Jens Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology , Gothenburg , Sweden ; Department of Biology and Biological Engineering, Chalmers University of Technology , Gothenburg , Sweden ; Novo Nordisk Foundation Center for Biosustainability , Hørsholm , Denmark
| |
Collapse
|
93
|
FudC, a protein primarily responsible for furfural detoxification in Corynebacterium glutamicum. Appl Microbiol Biotechnol 2015; 100:2685-92. [PMID: 26541332 DOI: 10.1007/s00253-015-7115-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 10/22/2022]
Abstract
Lignocellulosic hydrolysates contain compounds that inhibit microbial growth and fermentation, thereby decreasing the productivity of biofuel and biochemical production. In particular, the heterocyclic aldehyde furfural is one of the most toxic compounds found in these hydrolysates. We previously demonstrated that Corynebacterium glutamicum converts furfural into the less toxic compounds furfuryl alcohol and 2-furoic acid. To date, however, the genes involved in these oxidation and reduction reactions have not been identified in the C. glutamicum genome. Here, we show that Cgl0331 (designated FudC) is mainly responsible for the reduction of furfural into furfuryl alcohol in C. glutamicum. Deletion of the gene encoding FudC markedly diminished the in vivo reduction of furfural to furfuryl alcohol. Purified His-tagged FudC protein from Escherichia coli was also shown to convert furfural into furfuryl alcohol in an in vitro reaction utilizing NADPH, but not NADH, as a cofactor. Kinetic measurements demonstrated that FudC has a high affinity for furfural but has a narrow substrate range for other aldehydes compared to the protein responsible for furfural reduction in E. coli.
Collapse
|
94
|
Ceci A, Pierro L, Riccardi C, Pinzari F, Maggi O, Persiani AM, Gadd GM, Petrangeli Papini M. Biotransformation of β-hexachlorocyclohexane by the saprotrophic soil fungus Penicillium griseofulvum. CHEMOSPHERE 2015; 137:101-107. [PMID: 26071688 DOI: 10.1016/j.chemosphere.2015.05.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/26/2015] [Accepted: 05/21/2015] [Indexed: 06/04/2023]
Abstract
β-Hexachlorocyclohexane (β-HCH) is a persistent organic pollutant (POP) of global concern with potentially toxic effects on humans and ecosystems. Fungal tolerance and biotransformation of toxic substances hold considerable promise in environmental remediation technologies as many fungi can tolerate extreme environmental conditions and possess efficient extracellular degradative enzymes with relatively non-specific activities. In this research, we have investigated the potential of a saprotrophic soil fungus, Penicillium griseofulvum Dierckx, isolated from soils with high concentrations of isomers of hexachlorocyclohexane, to biotransform β-HCH, the most recalcitrant isomer to microbial activity. The growth kinetics of the fungus were characterized after growth in stirred liquid Czapek-Dox medium. It was found that P. griseofulvum was able to grow in the presence of 1 mg L(-1) β-HCH and in stressful nutritional conditions at different concentrations of sucrose in the medium (0 and 5 g L(-1)). The effects of β-HCH and the toluene, used as a solvent for β-HCH addition, on P. griseofulvum were investigated by means of a Phenotype MicroArray™ technique, which suggested the activation of certain metabolic pathways as a response to oxidative stress due to the presence of the xenobiotics. Gas chromatographic analysis of β-HCH concentration confirmed biodegradation of the isomer with a minimum value of β-HCH residual concentration of 18.6%. The formation of benzoic acid derivatives as dead-end products of β-HCH biotransformation was observed and this could arise from a possible biodegradation pathway for β-HCH with important connections to fungal secondary metabolism.
Collapse
Affiliation(s)
- Andrea Ceci
- Laboratorio Biodiversità dei Funghi, Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome 00185, Italy
| | - Lucia Pierro
- Laboratorio di impianti e processi industriali, Dipartimento di Chimica, Sapienza Università di Roma, Rome 00185, Italy
| | - Carmela Riccardi
- Settore Ricerca, Certificazione e Verifica, INAIL, Monteporzio Catone, Rome 00040, Italy
| | - Flavia Pinzari
- Consiglio per la Ricerca e l'Analisi dell'Economia Agraria, Centro di ricerca per lo studio delle Relazioni tra Pianta e Suolo, Rome 00184, Italy
| | - Oriana Maggi
- Laboratorio Biodiversità dei Funghi, Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome 00185, Italy
| | - Anna Maria Persiani
- Laboratorio Biodiversità dei Funghi, Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome 00185, Italy
| | - Geoffrey Michael Gadd
- Geomicrobiology Group, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK; Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, People's Republic of China
| | - Marco Petrangeli Papini
- Laboratorio di impianti e processi industriali, Dipartimento di Chimica, Sapienza Università di Roma, Rome 00185, Italy.
| |
Collapse
|
95
|
Increasing anaerobic acetate consumption and ethanol yields in Saccharomyces cerevisiae with NADPH-specific alcohol dehydrogenase. Appl Environ Microbiol 2015; 81:8108-17. [PMID: 26386051 DOI: 10.1128/aem.01689-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/12/2015] [Indexed: 12/18/2022] Open
Abstract
Saccharomyces cerevisiae has recently been engineered to use acetate, a primary inhibitor in lignocellulosic hydrolysates, as a cosubstrate during anaerobic ethanolic fermentation. However, the original metabolic pathway devised to convert acetate to ethanol uses NADH-specific acetylating acetaldehyde dehydrogenase and alcohol dehydrogenase and quickly becomes constrained by limited NADH availability, even when glycerol formation is abolished. We present alcohol dehydrogenase as a novel target for anaerobic redox engineering of S. cerevisiae. Introduction of an NADPH-specific alcohol dehydrogenase (NADPH-ADH) not only reduces the NADH demand of the acetate-to-ethanol pathway but also allows the cell to effectively exchange NADPH for NADH during sugar fermentation. Unlike NADH, NADPH can be freely generated under anoxic conditions, via the oxidative pentose phosphate pathway. We show that an industrial bioethanol strain engineered with the original pathway (expressing acetylating acetaldehyde dehydrogenase from Bifidobacterium adolescentis and with deletions of glycerol-3-phosphate dehydrogenase genes GPD1 and GPD2) consumed 1.9 g liter(-1) acetate during fermentation of 114 g liter(-1) glucose. Combined with a decrease in glycerol production from 4.0 to 0.1 g liter(-1), this increased the ethanol yield by 4% over that for the wild type. We provide evidence that acetate consumption in this strain is indeed limited by NADH availability. By introducing an NADPH-ADH from Entamoeba histolytica and with overexpression of ACS2 and ZWF1, we increased acetate consumption to 5.3 g liter(-1) and raised the ethanol yield to 7% above the wild-type level.
Collapse
|
96
|
Cunha JT, Aguiar TQ, Romaní A, Oliveira C, Domingues L. Contribution of PRS3, RPB4 and ZWF1 to the resistance of industrial Saccharomyces cerevisiae CCUG53310 and PE-2 strains to lignocellulosic hydrolysate-derived inhibitors. BIORESOURCE TECHNOLOGY 2015; 191:7-16. [PMID: 25974617 DOI: 10.1016/j.biortech.2015.05.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/30/2015] [Accepted: 05/02/2015] [Indexed: 05/13/2023]
Abstract
PRS3, RPB4 and ZWF1 were previously identified as key genes for yeast tolerance to lignocellulose-derived inhibitors. To better understand their contribution to yeast resistance to the multiple stresses occurring during lignocellulosic hydrolysate fermentations, we overexpressed these genes in two industrial Saccharomyces cerevisiae strains, CCUG53310 and PE-2, and evaluated their impact on the fermentation of Eucalyptus globulus wood and corn cob hydrolysates. PRS3 overexpression improved the fermentation rate (up to 32%) and productivity (up to 48%) in different hydrolysates. ZWF1 and RPB4 overexpression did not improve the fermentation performance, but their increased expression in the presence of acetic acid, furfural and hydroxymethylfurfural was found to contribute to yeast adaptation to these inhibitors. This study expands our understanding about the molecular mechanisms involved in industrial yeast tolerance to the stresses occurring during lignocellulosic bioethanol production and highlights the importance of selecting appropriate strain backgrounds/hydrolysates combinations when addressing further improvement of these processes.
Collapse
Affiliation(s)
- Joana T Cunha
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Tatiana Q Aguiar
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Aloia Romaní
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Carla Oliveira
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Lucília Domingues
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal.
| |
Collapse
|
97
|
Determinants of tolerance to inhibitors in hardwood spent sulfite liquor in genome shuffled Pachysolen tannophilus strains. Antonie van Leeuwenhoek 2015; 108:811-34. [PMID: 26231071 DOI: 10.1007/s10482-015-0537-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 07/15/2015] [Indexed: 01/05/2023]
Abstract
Genome shuffling was used to obtain Pachysolen tannophilus mutants with improved tolerance to inhibitors in hardwood spent sulfite liquor (HW SSL). Genome shuffled strains (GHW301, GHW302 and GHW303) grew at higher concentrations of HW SSL (80 % v/v) compared to the HW SSL UV mutant (70 % v/v) and the wild-type (WT) strain (50 % v/v). In defined media containing acetic acid (0.70-0.90 % w/v), GHW301, GHW302 and GHW303 exhibited a shorter lag compared to the acetic acid UV mutant, while the WT did not grow. Genome shuffled strains produced more ethanol than the WT at higher concentrations of HW SSL and an aspen hydrolysate. To identify the genetic basis of inhibitor tolerance, whole genome sequencing was carried out on GHW301, GHW302 and GHW303 and compared to the WT strain. Sixty single nucleotide variations were identified that were common to all three genome shuffled strains. Of these, 40 were in gene sequences and 20 were within 5 bp-1 kb either up or downstream of protein encoding genes. Based on the mutated gene products, mutations were grouped into functional categories and affected a variety of cellular functions, demonstrating the complexity of inhibitor tolerance in yeast. Sequence analysis of UV mutants (UAA302 and UHW303) from which GHW301, GHW302 and GHW303 were derived, confirmed the success of our cross-mating based genome shuffling strategy. Whole-genome sequencing analysis allowed identification of potential gene targets for tolerance to inhibitors in lignocellulosic hydrolysates.
Collapse
|
98
|
Kurosawa K, Laser J, Sinskey AJ. Tolerance and adaptive evolution of triacylglycerol-producing Rhodococcus opacus to lignocellulose-derived inhibitors. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:76. [PMID: 26052344 PMCID: PMC4456722 DOI: 10.1186/s13068-015-0258-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/29/2015] [Indexed: 05/24/2023]
Abstract
BACKGROUND Lignocellulosic biomass has been investigated as a renewable non-food source for production of biofuels. A significant technical challenge to using lignocellulose is the presence of microbial growth inhibitors generated during pretreatment processes. Triacylglycerols (TAGs) are potential precursors for lipid-based biofuel production. Rhodococcus opacus MITXM-61 is an oleaginous bacterium capable of producing large amounts of TAGs on high concentrations of glucose and xylose present in lignocellulosic hydrolysates. However, this strain is sensitive to ligonocellulose-derived inhibitors. To understand the toxic effects of the inhibitors in lignocellulosic hydrolysates, strain MITXM-61 was examined for tolerance toward the potential inhibitors and was subjected to adaptive evolution for the resistance to the inhibitors. RESULTS We investigated growth-inhibitory effects by potential lignocellulose-derived inhibitors of phenols (lignin, vanillin, 4-hydroxybenzaldehyde (4-HB), syringaldehyde), furans (furfural and 5-hydroxymethyl-2-furaldehyde), and organic acids (levulinic acid, formic acid, and acetic acid) on the growth and TAG production of strain MITXM-61. Phenols and furans exhibited potent inhibitory effects at a concentration of 1 g L(-1), while organic acids had insignificant impacts at concentrations of up to 2 g L(-1). In an attempt to improve the inhibitor tolerance of strain MITXM-61, we evaluated the adaptation of this strain to the potential inhibitors. Adapted mutants were generated on defined agar media containing lignin, 4-HB, and syringaldehyde. Strain MITXM-61(SHL33) with improved multiple resistance of lignin, 4-HB, and syringaldehyde was constructed through adaptive evolution-based strategies. The evolved strain exhibited a two- to threefold increase in resistance to lignin, 4-HB, and syringaldehyde at 50% growth-inhibitory concentrations, compared to the parental strain. When grown in genuine lignocellulosic hydrolysates of corn stover, wheat straw, and hardwood containing growth inhibitors, strain MITXM-61(SHL33) exhibited a markedly shortened lag phase in comparison with that of strain MITXM-61. CONCLUSION This study provides important clues to overcome the negative effects of inhibitors in lignocellulosic hydrolysates on TAG production of R. opacus cells. The findings can contribute to significant progress in detoxified pretreatment of hydrolysates and development of more efficient strains for industrial TAG fermentations of R. opacus using lignocellulosic biomass.
Collapse
Affiliation(s)
- Kazuhiko Kurosawa
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Josephine Laser
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- />Present address: Institute of Biotechnology, Department Applied and Molecular Microbiology Berlin University of Technology, Gustav-Meyer-Allee 25, Berlin, D-13355 Germany
| | - Anthony J Sinskey
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- />Engineering Systems Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| |
Collapse
|
99
|
Pornkamol U, Franzen CJ. Dynamic flux balancing elucidates NAD(P)H production as limiting response to furfural inhibition in Saccharomyces cerevisiae. Biotechnol J 2015; 10:1248-58. [PMID: 25880365 DOI: 10.1002/biot.201400833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 02/13/2015] [Accepted: 04/13/2015] [Indexed: 12/20/2022]
Abstract
Achieving efficient and economical lignocellulose-based bioprocess requires a robust organism tolerant to furfural, a major inhibitory compound present in lignocellulosic hydrolysate. The aim of this study was to develop a model that could generate quantitative descriptions of cell metabolism for elucidating the cell's adaptive response to furfural. Such a modelling tool could provide strategies for the design of more robust cells. A dynamic flux balance (dFBA) model of Saccharomyces cerevisiae was created by coupling a kinetic fermentation model with a previously published genome-scale stoichiometric model. The dFBA model was used for studying intracellular and extracellular flux responses to furfural perturbations under steady state and dynamic conditions. The predicted effects of furfural on dynamic flux profiles agreed well with previously published experimental results. The model showed that the yeast cell adjusts its metabolism in response to furfural challenge by increasing fluxes through the pentose phosphate pathway, TCA cycle, and proline and serine biosynthesis in order to meet the high demand of NAD(P)H cofactors. The model described here can be used to aid in systematic optimization of the yeast, as well as of the fermentation process, for efficient lignocellulosic ethanol production.
Collapse
Affiliation(s)
- Unrean Pornkamol
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand.
| | - Carl J Franzen
- Chalmers University of Technology, Department of Chemical and Biological Engineering, Division of Life Science - Industrial Biotechnology, Gothenburg, Sweden
| |
Collapse
|
100
|
Tan FR, Dai LC, Wu B, Qin H, Shui ZX, Wang JL, Zhu QL, Hu QC, Ruan ZY, He MX. Improving furfural tolerance of Zymomonas mobilis by rewiring a sigma factor RpoD protein. Appl Microbiol Biotechnol 2015; 99:5363-71. [PMID: 25895089 DOI: 10.1007/s00253-015-6577-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/23/2015] [Accepted: 03/25/2015] [Indexed: 01/21/2023]
Abstract
Furfural from lignocellulosic hydrolysates is the key inhibitor for bio-ethanol fermentation. In this study, we report a strategy of improving the furfural tolerance in Zymomonas mobilis on the transcriptional level by engineering its global transcription sigma factor (σ(70), RpoD) protein. Three furfural tolerance RpoD mutants (ZM4-MF1, ZM4-MF2, and ZM4-MF3) were identified from error-prone PCR libraries. The best furfural-tolerance strain ZM4-MF2 reached to the maximal cell density (OD600) about 2.0 after approximately 30 h, while control strain ZM4-rpoD reached its highest cell density of about 1.3 under the same conditions. ZM4-MF2 also consumed glucose faster and yield higher ethanol; expression levels and key Entner-Doudoroff (ED) pathway enzymatic activities were also compared to control strain under furfural stress condition. Our results suggest that global transcription machinery engineering could potentially be used to improve stress tolerance and ethanol production in Z. mobilis.
Collapse
Affiliation(s)
- Fu-Rong Tan
- Biogas Institute of Ministry of Agriculture, Biomass Energy Technology Research Centre, Section 4-13, Renming Nanlu, Chengdu, 610041, People's Republic of China
| | | | | | | | | | | | | | | | | | | |
Collapse
|