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Liu W, Liu P, Liu L, Sun H, Fan Y, Ma C, Ouyang J, Zheng Z. Promoting microbial fermentation in lignocellulosic hydrolysates by removal of inhibitors using MTES and PEI-modified chitosan-chitin nanofiber hybrid aerogel. Carbohydr Polym 2024; 328:121766. [PMID: 38220334 DOI: 10.1016/j.carbpol.2023.121766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/16/2024]
Abstract
To further enhance the removal efficiency for furanic and phenolic compounds in lignocellulosic hydrolysates, a new detoxification strategy was proposed, which retained fermentable sugars and promoted the growth and metabolism of subsequent bacteria. The best adsorbent (P/M-CCA) was prepared by hybrid chitosan-chitin nanofiber, graft modification with polyethylenimine, and silanization with methyl triethoxylsilane in order. Taken corn cob hydrolysate as object, the removal rates of HMF and furfural were 85.1 % and 99.0 %, respectively. The removal rates of six out of nine phenolic inhibitors were 100 %, and the other three were more than 65 %. Even better, the retention rates of glucose and xylose were both 100 %. In contrast to no growth in undetoxified hydrolysates, Bacillus coagulans grew normally in detoxified hydrolysates, and lactic acid reached 19.1 g/L after 12 h fermentation. P/M-CCA achieves both removal of multiple inhibitors and retain sugars, which would promote the valorization of highly toxic lignocellulosic hydrolysates.
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Affiliation(s)
- Wen Liu
- Nanjing Forestry University, Longpan Road 159, Nanjing, People's Republic of China
| | - Peng Liu
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang, People's Republic of China
| | - Liang Liu
- Nanjing Forestry University, Longpan Road 159, Nanjing, People's Republic of China.
| | - Huimin Sun
- Nanjing Forestry University, Longpan Road 159, Nanjing, People's Republic of China
| | - Yimin Fan
- Nanjing Forestry University, Longpan Road 159, Nanjing, People's Republic of China.
| | - Cuiqing Ma
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China.
| | - Jia Ouyang
- Nanjing Forestry University, Longpan Road 159, Nanjing, People's Republic of China.
| | - Zhaojuan Zheng
- College of Chemical Engineering, Nanjing Forestry University, Longpan Road 159, Nanjing 210037, People's Republic of China; Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, People's Republic of China.
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2
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Zhao R, Li H, Li Q, Jia Z, Li S, Zhao L, Li S, Wang Y, Fan W, Ren R, Yuan Z, Yang M, Wang X, Zhao X, Xiao W, Zhao J, Cao L. High titer (>100 g/L) ethanol production from pretreated corn stover hydrolysate by modified yeast strains. Bioresour Technol 2024; 391:129993. [PMID: 37944621 DOI: 10.1016/j.biortech.2023.129993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/29/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
Developing a reliable lignocellulose pretreatment method to extract mixed sugars and engineering efficient strains capable of utilizing xylose are crucial for advancing cellulosic ethanol production. In this study, chemical and characterization analyses revealed that alkali cooking can significantly remove lignin from lignocellulose crops. The highest amount of mixed sugar was obtained from corn stover hydrolysates with a 15 % solid loading. Our genetically engineered yeast strain ΔsnR4, derived from a well-staged WXY70, demonstrated excellent performance in low 10 % solids loading corn stover hydrolysate, producing a high ethanol yield of 0.485 g/g total sugars. When a combined NaOH-ball milling pretreatment strategy was applied at high solids loading, ΔsnR4 exhibited the maximum ethanol titer of 110.9 g/L within 36 h, achieving an ethanol yield of 92.9 % theoretical maximum. Therefore, ΔsnR4 is highly compatible with high solid loading NaOH-ball milling pretreatment, making it a potential candidate for industrial cellulosic ethanol.
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Affiliation(s)
- Rui Zhao
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hongshen Li
- Institute of New Energy Technology, Tsinghua University, Beijing 100084, China; ENN Group Co. Ltd., Langfang, Hebei 065001, China
| | - Qi Li
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zefang Jia
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Shizhong Li
- Institute of New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Ling Zhao
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Shan Li
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yuwei Wang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Wenxin Fan
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruoqi Ren
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zitong Yuan
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Mengchan Yang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xiaomei Wang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xin Zhao
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Weihua Xiao
- College of Engineering, China Agricultural University, Beijing 100083, China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Limin Cao
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China.
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3
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Menegon YA, Gross J, Jacobus AP. How adaptive laboratory evolution can boost yeast tolerance to lignocellulosic hydrolyses. Curr Genet 2022. [PMID: 35362784 DOI: 10.1007/s00294-022-01237-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/01/2022] [Accepted: 03/06/2022] [Indexed: 12/25/2022]
Abstract
The yeast Saccharomyces cerevisiae is an excellent candidate for establishing cell factories to convert lignocellulosic biomass into chemicals and fuels. To enable this technology, yeast robustness must be improved to withstand the fermentation inhibitors (e.g., weak organic acids, phenols, and furan aldehydes) resulting from biomass pretreatment and hydrolysis. Here, we discuss how evolution experiments performed in the lab, a method commonly known as adaptive laboratory evolution (ALE), may contribute to lifting yeast tolerance against the inhibitors of lignocellulosic hydrolysates (LCHs). The key is that, through the combination of whole-genome sequencing and reverse engineering, ALE provides a robust platform for discovering and testing adaptive alleles, allowing to explore the genetic underpinnings of yeast responses to LCHs. We review the insights gained from past evolution experiments with S. cerevisiae in LCH inhibitors and propose experimental designs to optimise the discovery of genetic variants adaptive to biomass toxicity. The knowledge gathered through ALE projects is envisaged as a roadmap to engineer superior yeast strains for biomass-based bioprocesses.
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Sun H, Liu L, Liu W, Liu Q, Zheng Z, Fan Y, Ouyang J. Removal of inhibitory furan aldehydes in lignocellulosic hydrolysates via chitosan-chitin nanofiber hybrid hydrogel beads. Bioresour Technol 2022; 346:126563. [PMID: 34910969 DOI: 10.1016/j.biortech.2021.126563] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 05/26/2023]
Abstract
To obtain fermentable sugars from lignocellulose, various inhibitors, especially furan aldehydes, are usually generated during the pretreatment process. These inhibitors are harmful to subsequent microbial growth and fermentation. In this study, a novel detoxification strategy was proposed to remove 5-hydroxymethylfurfural (HMF) and furfural while retaining glucose and xylose using self-prepared chitosan-chitin nanofiber hybrid hydrogel beads (C-CNBs). After C-CNBs treatment, the removal rates of HMF and furfural from sugarcane bagasse hydrolysates reached 63.1% and 68.4%, while the loss rates of glucose and xylose were only 6.3% and 8.2%, respectively. Two typical industrial strains grew well in monosaccharide-rich detoxified hydrolysates, with a specific growth rate at least 4.1 times that of undetoxified hydrolysates. Furthermore, adsorption mechanism analysis revealed that the Schiff base reaction and mesopore filling were involved in furan aldehyde adsorption. In total, C-CNBs provide an efficient and practical approach for the removal of furan aldehydes from lignocellulosic hydrolysates.
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Affiliation(s)
- Huimin Sun
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Liang Liu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Wen Liu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Qing Liu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Zhaojuan Zheng
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China.
| | - Yimin Fan
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Jia Ouyang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
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An N, Chen X, Sheng H, Wang J, Sun X, Yan Y, Shen X, Yuan Q. Rewiring the microbial metabolic network for efficient utilization of mixed carbon sources. J Ind Microbiol Biotechnol 2021; 48:6313286. [PMID: 34215883 PMCID: PMC8788776 DOI: 10.1093/jimb/kuab040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/26/2021] [Indexed: 11/14/2022]
Abstract
Carbon sources represent the most dominant cost factor in the industrial biomanufacturing of products. Thus, it has attracted much attention to seek cheap and renewable feedstocks, such as lignocellulose, crude glycerol, methanol, and carbon dioxide, for biosynthesis of value-added compounds. Co-utilization of these carbon sources by microorganisms not only can reduce the production cost but also serves as a promising approach to improve the carbon yield. However, co-utilization of mixed carbon sources usually suffers from a low utilization rate. In the past few years, the development of metabolic engineering strategies to enhance carbon source co-utilization efficiency by inactivation of carbon catabolite repression has made significant progress. In this article, we provide informative and comprehensive insights into the co-utilization of two or more carbon sources including glucose, xylose, arabinose, glycerol, and C1 compounds, and we put our focus on parallel utilization, synergetic utilization, and complementary utilization of different carbon sources. Our goal is not only to summarize strategies of co-utilization of carbon sources, but also to discuss how to improve the carbon yield and the titer of target products.
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Affiliation(s)
- Ning An
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xin Chen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Huakang Sheng
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jia Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yajun Yan
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, University of Georgia, Athens, GA 30602, USA
| | - Xiaolin Shen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Qipeng Yuan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Cubas-Cano E, Venus J, González-Fernández C, Tomás-Pejó E. Assessment of different Bacillus coagulans strains for l-lactic acid production from defined media and gardening hydrolysates: Effect of lignocellulosic inhibitors. J Biotechnol 2020; 323:9-16. [PMID: 32712129 DOI: 10.1016/j.jbiotec.2020.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 11/17/2022]
Abstract
Cellulose valorisation has been successfully addressed for years. However, the use of hemicellulosic hydrolysates is limited due to the presence of C5-sugars and inhibitors formed during pretreatment. Bacillus coagulans is one of the few bacteria able to utilize both C6- and C5-sugars to produce l-lactic acid, but its susceptibility to the lignocellulosic inhibitors needs further investigation. For such a purpose, the tolerance of different B. coagulans strains to increasing concentrations of inhibitors is studied. The isolated A162 strain reached the highest l-lactic acid productivity in all cases (up to 2.4 g L-1 h-1), even in presence of 5 g L-1 of furans and phenols. Remarkably, most of furans and phenolic aldehydes were removed from defined media and hemicellulosic gardening hydrolysate after fermentation with A162. Considering the high productivities and the biodetoxifying effect attained, A162 could be pointed out as a great candidate for valorisation of mixed sugars from hemicellulosic hydrolysates with high inhibitors concentration, promoting the implementation of lignocellulosic biorefineries.
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Affiliation(s)
- Enrique Cubas-Cano
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935, Móstoles, Spain
| | - Joachim Venus
- Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), 14469, Potsdam, Germany
| | | | - Elia Tomás-Pejó
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935, Móstoles, Spain.
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Liu H, Zhang J, Yuan J, Jiang X, Jiang L, Li Z, Yin Z, Du Y, Zhao G, Liu B, Huang D. Gene coexpression network analysis reveals a novel metabolic mechanism of Clostridium acetobutylicum responding to phenolic inhibitors from lignocellulosic hydrolysates. Biotechnol Biofuels 2020; 13:163. [PMID: 32999686 PMCID: PMC7520030 DOI: 10.1186/s13068-020-01802-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 09/12/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Lignocellulosic biomass is a promising resource of renewable biochemicals and biofuels. However, the presence of inhibitors existing in lignocellulosic hydrolysates (LCH) is a great challenge to acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum. In particular, phenolic compounds (PCs) from LCH severely block ABE production even at low concentrations. Thus, it is urgent to gain insight into the intracellular metabolic disturbances caused by phenolic inhibitors and elucidate the underlying mechanisms to identify key industrial bottlenecks that undermine efficient ABE production. RESULTS In this study, a time-course of ABE fermentation by C. acetobutylicum in the presence of four typical PCs (syringaldehyde, vanillin, ferulic acid, and p-coumaric acid) was characterized, respectively. Addition of PCs caused different irreversible effects on ABE production. Specifically, syringaldehyde showed the greatest inhibition to butanol production, followed by vanillin, ferulic acid, and p-coumaric acid. Subsequently, a weighted gene co-expression network analysis (WGCNA) based on RNA-sequencing data was applied to identify metabolic perturbations caused by four LCH-derived PCs, and extract the gene modules associated with extracellular fermentation traits. The hub genes in each module were subjected to protein-protein interaction analysis and enrichment analysis. The results showed that functional modules were PC-dependent and shared some unique features. Specifically, p-coumaric acid caused the most extensive transcriptomic disturbances, particularly affecting the gene expressions of ribosome proteins and the assembly of flagella, DNA replication, repair, and recombination; the addition of syringaldehyde caused significant metabolic disturbances on the gene expressions of ribosome proteins, starch and sucrose metabolism; vanillin mainly disturbed purine metabolism, sporulation and signal transduction; and ferulic acid caused a metabolic disturbance on glycosyl transferase-related gene expressions. CONCLUSION This study uncovers novel insights into the inhibitory mechanisms of PCs for the first time and provides guidance for future metabolic engineering efforts, which establishes a powerful foundation for the development of phenol-tolerant strains of C. acetobutylicum for economically sustainable ABE production with high productivity from lignocellulosic biomass.
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Affiliation(s)
- Huanhuan Liu
- State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Tianjin, 300457 China
- Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Ministry of Education, Tianjin, 300457 China
| | - Jing Zhang
- State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Tianjin, 300457 China
- Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Ministry of Education, Tianjin, 300457 China
| | - Jian Yuan
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Xiaolong Jiang
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Lingyan Jiang
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Zhenjing Li
- State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Tianjin, 300457 China
- Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Ministry of Education, Tianjin, 300457 China
| | - Zhiqiu Yin
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Yuhui Du
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Guang Zhao
- Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Qingdao, 266101 China
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
| | - Di Huang
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, 300457 China
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Díaz-Fernández D, Aguiar TQ, Martín VI, Romaní A, Silva R, Domingues L, Revuelta JL, Jiménez A. Microbial lipids from industrial wastes using xylose-utilizing Ashbya gossypii strains. Bioresour Technol 2019; 293:122054. [PMID: 31487616 DOI: 10.1016/j.biortech.2019.122054] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 05/08/2023]
Abstract
This work presents the exploitation of waste industrial by-products as raw materials for the production of microbial lipids in engineered strains of the filamentous fungus Ashbya gossypii. A lipogenic xylose-utilizing strain was used to apply a metabolic engineering approach aiming at relieving regulatory mechanisms to further increase the biosynthesis of lipids. Three genomic manipulations were applied: the overexpression of a feedback resistant form of the acetyl-CoA carboxylase enzyme; the expression of a truncated form of Mga2, a regulator of the main Δ9 desaturase gene; and the overexpression of an additional copy of DGA1 that codes for diacylglycerol acyltransferase. The performance of the engineered strain was evaluated in culture media containing mixed formulations of corn-cob hydrolysates, sugarcane molasses or crude glycerol. Our results demonstrate the efficiency of the engineered strains, which were able to accumulate about 40% of cell dry weight (CDW) in lipid content using organic industrial wastes as feedstocks.
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Affiliation(s)
- David Díaz-Fernández
- Metabolic Engineering Group, Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
| | - Tatiana Q Aguiar
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Victoria Isabel Martín
- Metabolic Engineering Group, Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
| | - Aloia Romaní
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Rui Silva
- 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
| | - José Luis Revuelta
- Metabolic Engineering Group, Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain.
| | - Alberto Jiménez
- Metabolic Engineering Group, Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain.
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Donzella S, Cucchetti D, Capusoni C, Rizzi A, Galafassi S, Chiara G, Compagno C. Engineering cytoplasmic acetyl-CoA synthesis decouples lipid production from nitrogen starvation in the oleaginous yeast Rhodosporidium azoricum. Microb Cell Fact 2019; 18:199. [PMID: 31727065 PMCID: PMC6854766 DOI: 10.1186/s12934-019-1250-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/04/2019] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Oleaginous yeasts are able to accumulate very high levels of neutral lipids especially under condition of excess of carbon and nitrogen limitation (medium with high C/N ratio). This makes necessary the use of two-steps processes in order to achieve high level of biomass and lipid. To simplify the process, the decoupling of lipid synthesis from nitrogen starvation, by establishing a cytosolic acetyl-CoA formation pathway alternative to the one catalysed by ATP-citrate lyase, can be useful. RESULTS In this work, we introduced a new cytoplasmic route for acetyl-CoA (AcCoA) formation in Rhodosporidium azoricum by overexpressing genes encoding for homologous phosphoketolase (Xfpk) and heterologous phosphotransacetylase (Pta). The engineered strain PTAPK4 exhibits higher lipid content and produces higher lipid concentration than the wild type strain when it was cultivated in media containing different C/N ratios. In a bioreactor process performed on glucose/xylose mixture, to simulate an industrial process for lipid production from lignocellulosic materials, we obtained an increase of 89% in final lipid concentration by the engineered strain in comparison to the wild type. This indicates that the transformed strain can produce higher cellular biomass with a high lipid content than the wild type. The transformed strain furthermore evidenced the advantage over the wild type in performing this process, being the lipid yields 0.13 and 0.05, respectively. CONCLUSION Our results show that the overexpression of homologous Xfpk and heterologous Pta activities in R. azoricum creates a new cytosolic AcCoA supply that decouples lipid production from nitrogen starvation. This metabolic modification allows improving lipid production in cultural conditions that can be suitable for the development of industrial bioprocesses using lignocellulosic hydrolysates.
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Affiliation(s)
- Silvia Donzella
- Department of Food, Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | | | - Claudia Capusoni
- Department of Food, Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | - Aurora Rizzi
- Department of Food, Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | - Silvia Galafassi
- Water Research Institute, National Research Council, Verbania, Italy
| | - Gambaro Chiara
- Eni S.p.A.-Renewable Energy and Environmental R&D Center-Istituto Eni Donegani, Novara, Italy
| | - Concetta Compagno
- Department of Food, Environmental and Nutritional Sciences, University of Milan, Milan, Italy.
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10
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Zhang K, Lu X, Li Y, Jiang X, Liu L, Wang H. New technologies provide more metabolic engineering strategies for bioethanol production in Zymomonas mobilis. Appl Microbiol Biotechnol 2019; 103:2087-2099. [PMID: 30661108 DOI: 10.1007/s00253-019-09620-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/02/2019] [Accepted: 01/03/2019] [Indexed: 02/06/2023]
Abstract
Bioethanol has been considered as a potentially renewable energy source, and metabolic engineering plays an important role in the production of biofuels. As an efficient ethanol-producing bacterium, Zymomonas mobilis has garnered special attention due to its high sugar uptake, ethanol yield, and tolerance. Different metabolic engineering strategies have been used to establish new metabolic pathways for Z. mobilis to broaden its substrate range, remove competing pathways, and enhance its tolerance to ethanol and lignocellulosic hydrolysate inhibitors. Recent advances in omics technology, computational modeling and simulation, system biology, and synthetic biology contribute to the efficient re-design and manipulation of microbes via metabolic engineering at the whole-cell level. In this review, we summarize the progress of some new technologies used for metabolic engineering to improve bioethanol production and tolerance in Z. mobilis. Some successful examples of metabolic engineering used to develop strains for ethanol production are described in detail. Lastly, some important strategies for future metabolic engineering efforts are also highlighted.
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Affiliation(s)
- Kun Zhang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Xinxin Lu
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Yi Li
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Xiaobing Jiang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Lei Liu
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Hailei Wang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China.
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Cunha JT, Soares PO, Romaní A, Thevelein JM, Domingues L. Xylose fermentation efficiency of industrial Saccharomyces cerevisiae yeast with separate or combined xylose reductase/xylitol dehydrogenase and xylose isomerase pathways. Biotechnol Biofuels 2019; 12:20. [PMID: 30705706 PMCID: PMC6348659 DOI: 10.1186/s13068-019-1360-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/18/2019] [Indexed: 05/12/2023]
Abstract
BACKGROUND Xylose isomerase (XI) and xylose reductase/xylitol dehydrogenase (XR/XDH) pathways have been extensively used to confer xylose assimilation capacity to Saccharomyces cerevisiae and tackle one of the major bottlenecks in the attainment of economically viable lignocellulosic ethanol production. Nevertheless, there is a lack of studies comparing the efficiency of those pathways both separately and combined. In this work, the XI and/or XR/XDH pathways were introduced into two robust industrial S. cerevisiae strains, evaluated in synthetic media and corn cob hemicellulosic hydrolysate and the results were correlated with the differential enzyme activities found in the xylose-pathway engineered strains. RESULTS The sole expression of XI was found to increase the fermentative capacity of both strains in synthetic media at 30 °C and 40 °C: decreasing xylitol accumulation and improving xylose consumption and ethanol production. Similar results were observed in fermentations of detoxified hydrolysate. However, in the presence of lignocellulosic-derived inhibitors, a positive synergistic effect resulted from the expression of both XI and XR/XDH, possibly caused by a cofactor equilibrium between the XDH and furan detoxifying enzymes, increasing the ethanol yield by more than 38%. CONCLUSIONS This study clearly shows an advantage of using the XI from Clostridium phytofermentans to attain high ethanol productivities and yields from xylose. Furthermore, and for the first time, the simultaneous utilization of XR/XDH and XI pathways was compared to the single expression of XR/XDH or XI and was found to improve ethanol production from non-detoxified hemicellulosic hydrolysates. These results extend the knowledge regarding S. cerevisiae xylose assimilation metabolism and pave the way for the construction of more efficient strains for use in lignocellulosic industrial processes.
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Affiliation(s)
- Joana T. Cunha
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Pedro O. Soares
- 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
| | - Johan M. Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Leuven-Heverlee, Flanders Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, 3001 Leuven-Heverlee, Flanders Belgium
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
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12
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.
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13
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Wang Y, Cao W, Luo J, Wan Y. Exploring the potential of lactic acid production from lignocellulosic hydrolysates with various ratios of hexose versus pentose by Bacillus coagulans IPE22. Bioresour Technol 2018; 261:342-349. [PMID: 29677662 DOI: 10.1016/j.biortech.2018.03.135] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
The aim of this study was to investigate the feasibility of utilizing different lignocellulosic hydrolysates with various hexose versus pentose (H:P) ratios to produce lactic acid (LA) from Bacillus coagulans IPE22 by fermentations with single and mixed sugar. In single sugar utilization, glucose tended to promote LA production, and xylose preferred to enhance cell growth. In mixed sugar utilization, glucose and pentose were consumed simultaneously when glucose concentration was lower than 20 g/L, and almost the same concentration of LA (50 g/L) was obtained regardless of the differences of H:P values. Finally, LA production from corn cob hydrolysates (CCH) contained 60 g/L mixed sugar verified the mechanisms found in the fermentations with simulated sugar mixture. Comparing with single glucose utilization, CCH utilization was faster and the yield of LA was not significantly affected. Therefore, the great potential of producing LA with lignocellulosic materials by B. coagulans was proved.
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Affiliation(s)
- Yujue Wang
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, People's Republic of China; University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Weifeng Cao
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Jianquan Luo
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, People's Republic of China; University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yinhua Wan
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, People's Republic of China; University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
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14
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Liu YF, Hsieh CW, Chang YS, Wung BS. Effect of acetic acid on ethanol production by Zymomonas mobilis mutant strains through continuous adaptation. BMC Biotechnol 2017; 17:63. [PMID: 28764759 PMCID: PMC5540488 DOI: 10.1186/s12896-017-0385-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/25/2017] [Indexed: 02/03/2023] Open
Abstract
Background Acetic acid is a predominant by-product of lignocellulosic biofuel process, which inhibits microbial biocatalysts. Development of bacterial strains that are tolerant to acetic acid is challenging due to poor understanding of the underlying molecular mechanisms. Results In this study, we generated and characterized two acetic acid-tolerant strains of Zymomonas mobilis using N-methyl-N′-nitro-N-nitrosoguanidine (NTG)-acetate adaptive breeding. Two mutants, ZMA-142 and ZMA-167, were obtained, showing a significant growth rate at a concentration of 244 mM sodium acetate, while the growth of Z. mobilis ATCC 31823 were completely inhibited in presence of 195 mM sodium acetate. Our data showed that acetate-tolerance of ZMA-167 was attributed to a co-transcription of nhaA from ZMO0117, whereas the co-transcription was absent in ATCC 31823 and ZMA-142. Moreover, ZMA-142 and ZMA-167 exhibited a converstion rate (practical ethanol yield to theorical ethanol yield) of 90.16% and 86% at 195 mM acetate-pH 5 stress condition, respectively. We showed that acid adaptation of ZMA-142 and ZMA-167 to 146 mM acetate increased ZMA-142 and ZMA-167 resulted in an increase in ethanol yield by 32.21% and 21.16% under 195 mM acetate-pH 5 stress condition, respectively. Conclusion The results indicate the acetate-adaptive seed culture of acetate-tolerant strains, ZMA-142 and ZMA-167, could enhance the ethanol production during fermentation.
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Affiliation(s)
- Yu-Fan Liu
- Division of Allergy, Department of Pediatrics, Chung-Shan Medical University Hospital, Taichung, Taiwan.,Department of Biomedical Sciences, College of Medicine Sciences and Technology, Chung Shan Medical University, Taichung, Taiwan
| | - Chia-Wen Hsieh
- Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan.
| | - Yao-Sheng Chang
- Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan
| | - Being-Sun Wung
- Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan
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15
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Llano T, Quijorna N, Andrés A, Coz A. Sugar, acid and furfural quantification in a sulphite pulp mill: Feedstock, product and hydrolysate analysis by HPLC/RID. ACTA ACUST UNITED AC 2017; 15:75-83. [PMID: 28725574 PMCID: PMC5503906 DOI: 10.1016/j.btre.2017.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 06/10/2017] [Accepted: 06/26/2017] [Indexed: 11/20/2022]
Abstract
Characterisation of the spent sulphite liquor, a sugar-rich residue was done. Four chromatographic methods for sugars and derivatives analysis were developed. Cross-linked Pb+2 columns were suitable for fast and reliable sugars separation. Cross-linked H+ columns were adequate for acids and furfurals separation. Methods developed were successfully assayed on woody materials and hydrolysates.
Waste from pulp and paper mills consist of sugar-rich fractions comprising hemicellulose derivatives and cellulose by-products. A complete characterisation of the waste streams is necessary to study the possibilities of an existing mill. In this work, four chromatographic methods have been developed to obtain the most suitable chromatographic method conditions for measuring woody feedstocks, lignocellulosic hydrolysates and cellulose pulp in sulphite pulping processes. The analysis of major and minor monosaccharides, aliphatic carboxylic acids and furfurals has been optimised. An important drawback of the spent liquors generated after sulphite pulping is their acidic nature, high viscosity and adhesive properties that interfere in the column lifetime. This work recommends both a CHO-782Pb column for the sugar analysis and an SH-1011 resin-based cross-linked gel column to separate low-molecular-weight chain acids, alcohols and furfurals. Such columns resulted in a good separation with long lifetime, wide pH operating range and low fouling issues.
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16
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Lodi G, Pellegrini LA, Aliverti A, Rivas Torres B, Bernardi M, Morbidelli M, Storti G. Recovery of monosaccharides from lignocellulosic hydrolysates by ion exclusion chromatography. J Chromatogr A 2017; 1496:25-36. [PMID: 28351538 DOI: 10.1016/j.chroma.2017.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 11/16/2022]
Abstract
The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chemical industry. Glucose, xylose and other monosaccharides can be easily produced by hydrolyzing cellulose and hemicellulose, the primary polysaccharides in biomass. However, the hydrolysis of biomass generates byproducts that, together with the mineral acid normally added in the hydrolysis step, have to be removed before the downstream conversion processes. In this work, the recovery of monosaccharides from lignocellulosic hydrolysates by means of Ion Exclusion Chromatography (IEC) has been studied. The analyzed process relies on new pretreatment and hydrolysis steps, involving the neutralization of the hydrolysate with sodium hydroxide. The adsorption behavior of the main components involved in the separation has been experimentally investigated. Pulse tests at the high loading encountered in preparative conditions have been performed for a selected group of model components found in the hydrolysates. For all the electrolytes, the retention volume fraction was always between the interparticle porosity and the total column porosity, confirming that ion exclusion was the dominant retention mechanism. On the other hand, sugars eluted before the total column porosity, indicating partial steric exclusion from the resin pores. This observation was then confirmed by size-exclusion experiments with polyethylene glycol standards, from which the distribution coefficient of the studied sugars has been determined. The comparison between the elution profiles of the same sugars in pure form and as a mixture present in the hydrolysate showed differences in both peak shape and retention times. Therefore, an investigation of the influence of the main electrolytes contained in the hydrolysates on sugars adsorption has been performed through the pulse on a plateau method. The electrolytes were found to enhance the sugars retention by promoting their adsorption onto the resin. However, this effect was not sufficient to explain the observed differences, which were effectively explained in terms of viscous fingering, due to the high viscosity differences between the eluent and the sample. A previously developed model for IEC has been updated to take into account all the observed phenomena and applied to simulate the experimental results. The proposed model was in good agreement with the batch-column elution profiles both for the pure components and for the actual hydrolysate, allowing a quantitative description of the separation.
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Affiliation(s)
- Gabriele Lodi
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Laura Annamaria Pellegrini
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Alessandro Aliverti
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
| | - Beatriz Rivas Torres
- Biochemtex S.p.A., Gruppo Mossi & Ghisolfi, Strada Savonesa 9, 15050 Rivalta Scrivia (AL), Italy
| | - Marco Bernardi
- Biochemtex S.p.A., Gruppo Mossi & Ghisolfi, Strada Savonesa 9, 15050 Rivalta Scrivia (AL), Italy
| | - Massimo Morbidelli
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
| | - Giuseppe Storti
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
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17
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Henriques SF, Mira NP, Sá-Correia I. Genome-wide search for candidate genes for yeast robustness improvement against formic acid reveals novel susceptibility (Trk1 and positive regulators) and resistance (Haa1-regulon) determinants. Biotechnol Biofuels 2017; 10:96. [PMID: 28428821 PMCID: PMC5395885 DOI: 10.1186/s13068-017-0781-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 04/11/2017] [Indexed: 05/06/2023]
Abstract
BACKGROUND Formic acid is an inhibitory compound present in lignocellulosic hydrolysates. Understanding the complex molecular mechanisms underlying Saccharomyces cerevisiae tolerance to this weak acid at the system level is instrumental to guide synthetic pathway engineering for robustness improvement of industrial strains envisaging their use in lignocellulosic biorefineries. RESULTS This study was performed to identify, at a genome-wide scale, genes whose expression confers protection or susceptibility to formic acid, based on the screening of a haploid deletion mutant collection to search for these phenotypes in the presence of 60, 70 and 80 mM of this acid, at pH 4.5. This chemogenomic analysis allowed the identification of 172 determinants of tolerance and 41 determinants of susceptibility to formic acid. Clustering of genes required for maximal tolerance to this weak acid, based on their biological function, indicates an enrichment of those involved in intracellular trafficking and protein synthesis, cell wall and cytoskeleton organization, carbohydrate metabolism, lipid, amino acid and vitamin metabolism, response to stress, chromatin remodelling, transcription and internal pH homeostasis. Among these genes is HAA1 encoding the main transcriptional regulator of yeast transcriptome reprograming in response to acetic acid and genes of the Haa1-regulon; all demonstrated determinants of acetic acid tolerance. Among the genes that when deleted lead to increased tolerance to formic acid, TRK1, encoding the high-affinity potassium transporter and a determinant of resistance to acetic acid, was surprisingly found. Consistently, genes encoding positive regulators of Trk1 activity were also identified as formic acid susceptibility determinants, while a negative regulator confers protection. At a saturating K+ concentration of 20 mM, the deletion mutant trk1Δ was found to exhibit a much higher tolerance compared with the parental strain. Given that trk1Δ accumulates lower levels of radiolabelled formic acid, compared to the parental strain, it is hypothesized that Trk1 facilitates formic acid uptake into the yeast cell. CONCLUSIONS The list of genes resulting from this study shows a few marked differences from the list of genes conferring protection to acetic acid and provides potentially valuable information to guide improvement programmes for the development of more robust strains against formic acid.
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Affiliation(s)
- Sílvia F. Henriques
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Nuno P. Mira
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, 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
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18
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Ma K, Hu G, Pan L, Wang Z, Zhou Y, Wang Y, Ruan Z, He M. Highly efficient production of optically pure l-lactic acid from corn stover hydrolysate by thermophilic Bacillus coagulans. Bioresour Technol 2016; 219:114-122. [PMID: 27479802 DOI: 10.1016/j.biortech.2016.07.100] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 07/21/2016] [Accepted: 07/24/2016] [Indexed: 05/13/2023]
Abstract
A thermophilic strain Bacillus coagulans (NBRC 12714) was employed to produce l-lactic acid from corn stover hydrolysate in membrane integrated continuous fermentation. The strain NBRC 12714 metabolized glucose and xylose by the Embden-Meyerhof-Parnas pathway (EMP) and the pentose phosphate pathway (PPP), producing l-lactic acid with optical purity >99.5%. The overall l-lactic acid titer of 92g/l with a yield of 0.91g/g and a productivity of 13.8g/l/h were achieved at a dilution rate of 0.15h(-1). The productivity obtained was 1.6-fold than that of conventional continuous fermentation without cell recycling, and also was the highest among the relevant studies ever reported. These results indicated that the process developed had great potential for economical industrial production of l-lactic acid from lignocellulosic biomass.
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Affiliation(s)
- Kedong Ma
- College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, PR China
| | - Guoquan Hu
- Key Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture, Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China
| | - Liwei Pan
- College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, PR China
| | - Zichao Wang
- College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, PR China
| | - Yi Zhou
- College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, PR China
| | - Yanwei Wang
- Key Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture, Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China
| | - Zhiyong Ruan
- Key Laboratory of Microbial Resources (Ministry of Agriculture, China), Institute of Agricultural Resources and Regional Planning, CAAS, Beijing 100081, PR China
| | - Mingxiong He
- Key Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture, Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China.
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Fei Q, O’Brien M, Nelson R, Chen X, Lowell A, Dowe N. Enhanced lipid production by Rhodosporidium toruloides using different fed-batch feeding strategies with lignocellulosic hydrolysate as the sole carbon source. Biotechnol Biofuels 2016; 9:130. [PMID: 27340432 PMCID: PMC4918137 DOI: 10.1186/s13068-016-0542-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/02/2016] [Indexed: 05/15/2023]
Abstract
BACKGROUND Industrial biotechnology that is able to provide environmentally friendly bio-based products has attracted more attention in replacing petroleum-based industries. Currently, most of the carbon sources used for fermentation-based bioprocesses are obtained from agricultural commodities that are used as foodstuff for human beings. Lignocellulose-derived sugars as the non-food, green, and sustainable alternative carbon sources have great potential to avoid this dilemma for producing the renewable, bio-based hydrocarbon fuel precursors, such as microbial lipid. Efficient bioconversion of lignocellulose-based sugars into lipids is one of the critical parameters for industrial application. Therefore, the fed-batch cultivation, which is a common method used in industrial applications, was investigated to achieve a high cell density culture along with high lipid yield and productivity. RESULTS In this study, several fed-batch strategies were explored to improve lipid production using lignocellulosic hydrolysates derived from corn stover. Compared to the batch culture giving a lipid yield of 0.19 g/g, the dissolved-oxygen-stat feeding mode increased the lipid yield to 0.23 g/g and the lipid productivity to 0.33 g/L/h. The pulse feeding mode further improved lipid productivity to 0.35 g/L/h and the yield to 0.24 g/g. However, the highest lipid yield (0.29 g/g) and productivity (0.4 g/L/h) were achieved using an automated online sugar control feeding mode, which gave a dry cell weight of 54 g/L and lipid content of 59 % (w/w). The major fatty acids of the lipid derived from lignocellulosic hydrolysates were predominately palmitic acid and oleic acid, which are similar to those of conventional oilseed plants. CONCLUSIONS Our results suggest that the fed-batch feeding strategy can strongly influence the lipid production. The online sugar control feeding mode was the most appealing strategy for high cell density, lipid yield, and lipid productivity using lignocellulosic hydrolysates as the sole carbon source.
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Affiliation(s)
- Qiang Fei
- />School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, 710049 China
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Marykate O’Brien
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Robert Nelson
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Xiaowen Chen
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Andrew Lowell
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
- />KBI Biopharma, 2500 Central Ave, Boulder, CO 80301 USA
| | - Nancy Dowe
- />National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA
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