1
|
Tjo H, Jiang V, Joseph JA, Conway JM. Maltodextrin transport in the extremely thermophilic, lignocellulose degrading bacterium Anaerocellum bescii (f. Caldicellulosiruptor bescii). J Bacteriol 2025; 207:e0040124. [PMID: 40304524 PMCID: PMC12096829 DOI: 10.1128/jb.00401-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2024] [Accepted: 03/24/2025] [Indexed: 05/02/2025] Open
Abstract
Sugar transport into microbial cells is a critical, yet understudied step in the conversion of lignocellulosic biomass to metabolic products. Anaerocellum bescii (formerly Caldicellulosiruptor bescii) is an extremely thermophilic, anaerobic bacterium that readily degrades the cellulose and hemicellulose components of lignocellulosic biomass into a diversity of oligosaccharide substrates. Despite significant understanding of how this microorganism degrades lignocellulose, the mechanisms underlying its highly efficient transport of the released oligosaccharides into the cell are comparatively underexplored. Here, we identify and characterize the ATP-binding cassette (ABC) transporters in A. bescii governing maltodextrin transport. Utilizing past transcriptomic studies on Anaerocellum and Caldicellulosiruptor species, we identify two maltodextrin transporters in A. bescii and express and purify their substrate-binding proteins (Athe_2310 and Athe_2574) for characterization. Using differential scanning calorimetry and isothermal titration calorimetry, we show that Athe_2310 strongly interacts with shorter maltodextrins, such as maltose and trehalose, with dissociation constants in the micromolar range, while Athe_2574 binds longer maltodextrins, with dissociation constants in the sub-micromolar range. Using a sequence-structure-function comparison approach combined with molecular modeling, we provide context for the specificity of each of these substrate-binding proteins. We propose that A. bescii utilizes orthogonal ABC transporters to uptake malto-oligosaccharides of different lengths to maximize transport efficiency. IMPORTANCE Here, we reveal the biophysical and structural basis for oligosaccharide transport by two maltodextrin ATP-binding cassette (ABC) transporters in Anaerocellum bescii. This is the first biophysical characterization of carbohydrate uptake in this organism and establishes a workflow for characterizing other oligosaccharide transporters in A. bescii and similar biomass-degrading thermophiles of interest for lignocellulosic bioprocessing. By deciphering the mechanisms underlying high-affinity sugar uptake in A. bescii, we shed light on an underexplored step between extracellular lignocellulose degradation and intracellular conversion of sugars to metabolic products. This understanding will expand opportunities for harnessing sugar transport in thermophiles to reshape lignocellulose bioprocessing as part of a renewable bioeconomy.
Collapse
Affiliation(s)
- Hansen Tjo
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA
| | - Virginia Jiang
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA
| | - Jerelle A. Joseph
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, New Jersey, USA
| | - Jonathan M. Conway
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, New Jersey, USA
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey, USA
- High Meadows Environmental Institute, Princeton University, Princeton, New Jersey, USA
| |
Collapse
|
2
|
Abo-Zaid GA, Darwish MH, Ghozlan HA, Abdel-Gayed MA, Sabry SA. Sustainable management of peanut damping-off and root rot diseases caused by Rhizoctonia solani using environmentally friendly bio-formulations prepared from batch fermentation broth of chitinase-producing Streptomyces cellulosae. BMC PLANT BIOLOGY 2024; 24:760. [PMID: 39118060 PMCID: PMC11312809 DOI: 10.1186/s12870-024-05441-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 07/22/2024] [Indexed: 08/10/2024]
Abstract
BACKGROUND Soil-borne plant diseases represent a severe problem that negatively impacts the production of food crops. Actinobacteria play a vital role in biocontrolling soil-borne fungi. AIM AND OBJECTIVES The target of the present study is to test the antagonistic activity of chitinase-producing Streptomyces cellulosae Actino 48 (accession number, MT573878) against Rhizoctonia solani. Subsequently, maximization of Actino 48 production using different fermentation processes in a stirred tank bioreactor. Finally, preparation of bio-friendly formulations prepared from the culture broth of Actino 48 using talc powder (TP) and bentonite in a natural as well as nano forms as carriers. Meanwhile, investigating their activities in reducing the damping-off and root rot diseases of peanut plants, infected by R. solani under greenhouse conditions. RESULTS Actino 48 was found to be the most significant antagonistic isolate strain at p ≤ 0.05 and showed the highest inhibition percentage of fungal mycelium growth, which reached 97%. The results of scanning electron microscope (SEM) images analysis showed a large reduction in R. solani mycelia mass. Additionally, many aberrations changes and fungal hypha damages were found. Batch fermentation No. 2, which was performed using agitation speed of 200 rpm, achieved high chitinase activity of 0.1163 U mL- 1 min- 1 with a yield coefficient of 0.004 U mL- 1 min- 1 chitinase activity/g chitin. Nano-talc formulation of Actino 48 had more a significant effect compared to the other formulations in reducing percentages of damping-off and root rot diseases that equal to 19.05% and 4.76% with reduction percentages of 60% and 80%, respectively. The healthy survival percentage of peanut plants recorded 76.19%. Furthermore, the nano-talc formulation of Actino 48 was sufficient in increasing the dry weight of the peanut plants shoot, root systems, and the total number of peanut pods with increasing percentages of 47.62%, 55.62%, and 38.07%, respectively. CONCLUSION The bio-friendly formulations of actinobacteria resulting from this investigation may play an active role in managing soil-borne diseases.
Collapse
Affiliation(s)
- Gaber Attia Abo-Zaid
- Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City, Alexandria, 21934, Egypt.
| | - Mai H Darwish
- Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, 21526, Egypt
| | - Hanan A Ghozlan
- Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, 21526, Egypt
| | - Muhammad A Abdel-Gayed
- Onion, Garlic and Oil Crops Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Center, Giza, 12619, Egypt
| | - Soraya A Sabry
- Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, 21526, Egypt
| |
Collapse
|
3
|
Tjo H, Conway JM. Sugar transport in thermophiles: Bridging lignocellulose deconstruction and bioconversion. J Ind Microbiol Biotechnol 2024; 51:kuae020. [PMID: 38866721 PMCID: PMC11212667 DOI: 10.1093/jimb/kuae020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 06/11/2024] [Indexed: 06/14/2024]
Abstract
Biomass degrading thermophiles play an indispensable role in building lignocellulose-based supply chains. They operate at high temperatures to improve process efficiencies and minimize mesophilic contamination, can overcome lignocellulose recalcitrance through their native carbohydrate-active enzyme (CAZyme) inventory, and can utilize a wide range of sugar substrates. However, sugar transport in thermophiles is poorly understood and investigated, as compared to enzymatic lignocellulose deconstruction and metabolic conversion of sugars to value-added chemicals. Here, we review the general modes of sugar transport in thermophilic bacteria and archaea, covering the structural, molecular, and biophysical basis of their high-affinity sugar uptake. We also discuss recent genetic studies on sugar transporter function. With this understanding of sugar transport, we discuss strategies for how sugar transport can be engineered in thermophiles, with the potential to enhance the conversion of lignocellulosic biomass into renewable products. ONE-SENTENCE SUMMARY Sugar transport is the understudied link between extracellular biomass deconstruction and intracellular sugar metabolism in thermophilic lignocellulose bioprocessing.
Collapse
Affiliation(s)
- Hansen Tjo
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Jonathan M Conway
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, USA
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ 08544, USA
- High Meadows Environmental Institute, Princeton University, Princeton, NJ 08544, USA
| |
Collapse
|
4
|
Xiao Y, Dong S, Liu YJ, You C, Feng Y, Cui Q. Key roles of β-glucosidase BglA for the catabolism of both laminaribiose and cellobiose in the lignocellulolytic bacterium Clostridium thermocellum. Int J Biol Macromol 2023; 250:126226. [PMID: 37558019 DOI: 10.1016/j.ijbiomac.2023.126226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/31/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
The thermophilic bacterium Clostridium thermocellum efficiently degrades polysaccharides into oligosaccharides. The metabolism of β-1,4-linked cello-oligosaccharides is initiated by three enzymes, i.e., the cellodextrin phosphorylase (Cdp), the cellobiose phosphorylase (Cbp), and the β-glucosidase A (BglA), in C. thermocellum. In comparison, how the oligosaccharides containing other kinds of linkage are utilized is rarely understood. In this study, we found that BglA could hydrolyze the β-1,3-disaccharide laminaribiose with much higher activity than that against the β-1,4-disaccharide cellobiose. The structural basis of the substrate specificity was analyzed by crystal structure determination and molecular docking. Genetic deletions of BglA and Cbp, respectively, and enzymatic analysis of cell extracts demonstrated that BglA is the key enzyme responsible for laminaribiose metabolism. Furthermore, the deletion of BglA can suppress the expression of Cbp and the deletion of Cbp can up-regulate the expression of BglA, indicating that BglA and Cbp have cross-regulation and BglA is also critical for cellobiose metabolism. These insights pave the way for both a fundamental understanding of metabolism and regulation in C. thermocellum and emphasize the importance of the degradation and utilization of polysaccharides containing β-1,3-linked glycosidic bonds in lignocellulose biorefinery.
Collapse
Affiliation(s)
- Yan Xiao
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
| |
Collapse
|
5
|
Utilization of Monosaccharides by Hungateiclostridium thermocellum ATCC 27405 through Adaptive Evolution. Microorganisms 2021; 9:microorganisms9071445. [PMID: 34361881 PMCID: PMC8303734 DOI: 10.3390/microorganisms9071445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 12/13/2022] Open
Abstract
Hungateiclostridium thermocellum ATCC 27405 is a promising bacterium for consolidated bioprocessing with a robust ability to degrade lignocellulosic biomass through a multienzyme cellulosomal complex. The bacterium uses the released cellodextrins, glucose polymers of different lengths, as its primary carbon source and energy. In contrast, the bacterium exhibits poor growth on monosaccharides such as fructose and glucose. This phenomenon raises many important questions concerning its glycolytic pathways and sugar transport systems. Until now, the detailed mechanisms of H. thermocellum adaptation to growth on hexose sugars have been relatively poorly explored. In this study, adaptive laboratory evolution was applied to train the bacterium in hexose sugars-based media, and genome resequencing was used to detect the genes that got mutated during adaptation period. RNA-seq data of the first culture growing on either fructose or glucose revealed that several glycolytic genes in the Embden–Mayerhof–Parnas pathway were expressed at lower levels in these cells than in cellobiose-grown cells. After seven consecutive transfer events on fructose and glucose (~42 generations for fructose-adapted cells and ~40 generations for glucose-adapted cells), several genes in the EMP glycolysis of the evolved strains increased the levels of mRNA expression, accompanied by a faster growth, a greater biomass yield, a higher ethanol titer than those in their parent strains. Genomic screening also revealed several mutation events in the genomes of the evolved strains, especially in those responsible for sugar transport and central carbon metabolism. Consequently, these genes could be applied as potential targets for further metabolic engineering to improve this bacterium for bio-industrial usage.
Collapse
|
6
|
Xu C, Su X, Wang J, Zhang F, Shen G, Yuan Y, Yan L, Tang H, Song F, Wang W. Characteristics and functional bacteria in a microbial consortium for rice straw lignin-degrading. BIORESOURCE TECHNOLOGY 2021; 331:125066. [PMID: 33812140 DOI: 10.1016/j.biortech.2021.125066] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
The degradation of lignin is the main rate-limiting step in the bio-pulping of rice straw. A lignin-degrading bacterial consortium LDC, which can efficiently degrade lignin of reed, was screened in the early stage of our laboratory work. In present study, 7-day incubation of LDC can degrade rice straw lignin by 31.18% in mineral salt medium. The communities' structure of different incubation phases varied greatly, in which high abundance (44.78%) of Anaerocolumna was first found. The expression levels of lignin degradation enzyme class II peroxidase (AA2), vanillyl alcohol oxidase (AA4) and 1,4-benzoquinone reductase (AA6) during peak phase (48 h) were significantly up-regulated than initial phase (24 h), increasing by 112%, 165% and 67%, respectively, and 42.86% AA2 was from Thaurea; 100% AA4 was from Clostridium; 62.5% AA6 was from Pseudomonas. These provide microbial resources and data support for the industrialization of rice straw bio-pulping.
Collapse
Affiliation(s)
- Congfeng Xu
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China
| | - Xin Su
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China
| | - Jinghong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China
| | - Fangzheng Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China
| | - Guinan Shen
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China; Engineering Research Center of Processing and Utilization of Grain By-products, Ministry of Education, Daqing 163319, People's Republic of China
| | - Yuan Yuan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China; Engineering Research Center of Processing and Utilization of Grain By-products, Ministry of Education, Daqing 163319, People's Republic of China
| | - Lei Yan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China; Engineering Research Center of Processing and Utilization of Grain By-products, Ministry of Education, Daqing 163319, People's Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Fuqiang Song
- College of Life Science, Heilongjiang University, Harbin 150080, People's Republic of China
| | - Weidong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, People's Republic of China; Engineering Research Center of Processing and Utilization of Grain By-products, Ministry of Education, Daqing 163319, People's Republic of China.
| |
Collapse
|
7
|
Ahamed F, Song HS, Ho YK. Modeling coordinated enzymatic control of saccharification and fermentation by Clostridium thermocellum during consolidated bioprocessing of cellulose. Biotechnol Bioeng 2021; 118:1898-1912. [PMID: 33547803 DOI: 10.1002/bit.27705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 11/09/2022]
Abstract
Consolidated bioprocessing (CBP) of cellulose is a cost-effective route to produce valuable biochemicals by integrating saccharification, fermentation and cellulase synthesis in a single step. However, the lack of understanding of governing factors of interdependent saccharification and fermentation in CBP eludes reliable process optimization. Here, we propose a new framework that synergistically couples population balances (to simulate cellulose depolymerization) and cybernetic models (to model enzymatic regulation of fermentation) to enable improved understanding of CBP. The resulting framework, named the unified cybernetic-population balance model (UC-PBM), enables simulation of CBP driven by coordinated control of enzyme synthesis through closed-loop interactions. UC-PBM considers two key aspects in controlling CBP: (1) heterogeneity in cellulose properties and (2) cellular regulation of competing cell growth and cellulase secretion. In a case study on Clostridium thermocellum, UC-PBM not only provides a decent fit with various exometabolomic data, but also reveals that: (i) growth-decoupled cellulase-secreting pathways are only activated during famine conditions to promote the production of growth substrates, and (ii) starting cellulose concentration has a strong influence on the overall flux distribution. Equipped with mechanisms of cellulose degradation and fermentative regulations, UC-PBM is practical to explore phenotypic functions for primary evaluation of microorganisms' potential for metabolic engineering and optimal design of bioprocess.
Collapse
Affiliation(s)
- Firnaaz Ahamed
- Chemical Engineering Discipline, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor, Malaysia
| | - Hyun-Seob Song
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Department of Food Science and Technology, Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Yong Kuen Ho
- Chemical Engineering Discipline, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor, Malaysia.,Monash-Industry Palm Oil Education and Research Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor, Malaysia
| |
Collapse
|
8
|
Althuri A, Venkata Mohan S. Sequential and consolidated bioprocessing of biogenic municipal solid waste: A strategic pairing of thermophilic anaerobe and mesophilic microaerobe for ethanol production. BIORESOURCE TECHNOLOGY 2020; 308:123260. [PMID: 32251860 DOI: 10.1016/j.biortech.2020.123260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Feedstock availability and its pretreatment, high process economics and insufficient ethanol (HEt) titres necessitated the bioprocesses that are sustainable. The advanced consolidated bioprocessing (CBPSeq) strategy presently considered for improved HEt production involves, sequential coupling of CBP thermophile, Clostridium thermocellum ATCC-27405 with mesophilic microaerobe, Pichia stipitis NCIM-3498. Biogenic municipal solid waste (BMSW) pretreated with 0.5% NaOH (CSPBMSW) served as the sole carbon source. CBPSeq (23.99 g/L) fared better than CBP standalone (18.10 g/L) wherein 1.32-folds improvement in HEt titre was recorded. Considering insufficient xylanase titre in cellulosome complex of C. thermocellum, CBPSeq was performed employing exogenous xylanases (CBPSeqE) to improve xylan digestibility and HEt yield. CBPSeqE-II biosystem at pH 5 showed maximum HEt titre of 36.90 g/L which corresponds to yield of 0.26 g HEt/ g CSPBMSW. This study substantiates efficacy of CBPSeqE-II biosystem in sustainable bioethanol production from BMSW in a single reactor without laborious steps.
Collapse
Affiliation(s)
- Avanthi Althuri
- Bioengineering and Environmental Sciences Lab, Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, Telangana, India.
| | - S Venkata Mohan
- Bioengineering and Environmental Sciences Lab, Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, Telangana, India
| |
Collapse
|
9
|
Darwish AMG, Abdel-Azeem AM. Chaetomium Enzymes and Their Applications. Fungal Biol 2020. [DOI: 10.1007/978-3-030-31612-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
10
|
Wang F, Wang M, Zhao Q, Niu K, Liu S, He D, Liu Y, Xu S, Fang X. Exploring the Relationship Between Clostridium thermocellum JN4 and Thermoanaerobacterium thermosaccharolyticum GD17. Front Microbiol 2019; 10:2035. [PMID: 31551972 PMCID: PMC6746925 DOI: 10.3389/fmicb.2019.02035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/19/2019] [Indexed: 11/13/2022] Open
Abstract
Characterizing and engineering microbial communities for lignocellulosic biofuel production has received widespread attention. Previous research has established that Clostridium thermocellum JN4 and Thermoanaerobacterium thermosaccharolyticum GD17 coculture significantly improves overall cellulosic biofuel production efficiency. Here, we investigated this interaction and revealed the mechanism underlying the improved efficiency observed. In contrast to the previously reported mutualistic relationship, a harmful effect toward C. thermocellum JN4 was observed in these microbial consortia. Although T. thermosaccharolyticum GD17 relieves the carbon catabolite repression of C. thermocellum JN4 regarding obtaining more cellobiose or glucose released from lignocellulose, T. thermosaccharolyticum GD17 significantly hampers the growth of C. thermocellum JN4 in coculture. The increased formation of end products is due to the strong competitive metabolic advantage of T. thermosaccharolyticum GD17 over C. thermocellum JN4 in the conversion of glucose or cellobiose into final products. The possibility of controlling and rebalancing these microbial consortia to modulate cellulose degradation was achieved by adding T. thermosaccharolyticum GD17 stimulants into the system. As cellulolytic bacteria are usually at a metabolic disadvantage, these discoveries may apply to a large proportion of cellulosic biofuel-producing microbial consortia. These findings provide a reference for engineering efficient and modular microbial consortia for modulating cellulosic conversion.
Collapse
Affiliation(s)
- Fangzhong Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,Center for Biosafety Research and Strategy, Tianjin University, Tianjin, China
| | - Mingyu Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qi Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Kangle Niu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Shasha Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Didi He
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yan Liu
- College of Life Science, Qufu Normal University, Qufu, China
| | - Shiping Xu
- School of Environmental Science and Engineering, Shandong University, Qingdao, China
| | - Xu Fang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| |
Collapse
|
11
|
Influence of substrate loadings on the consolidated bioprocessing of rice straw and sugarcane bagasse biomass using Ruminiclostridium thermocellum. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biteb.2019.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
12
|
|
13
|
Tiwari S, Verma T. Cellulose as a Potential Feedstock for Cellulose Enzyme Production. Fungal Biol 2019. [DOI: 10.1007/978-3-030-14726-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
14
|
Singh N, Mathur AS, Gupta RP, Barrow CJ, Tuli D, Puri M. Enhanced cellulosic ethanol production via consolidated bioprocessing by Clostridium thermocellum ATCC 31924☆. BIORESOURCE TECHNOLOGY 2018; 250:860-867. [PMID: 30001594 DOI: 10.1016/j.biortech.2017.11.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 05/23/2023]
Abstract
The production of bioethanol was studied by the cultivation of Clostridium thermocellum ATCC 31924 in MTC medium including crystalline cellulose as the sole substrate. The effects of key operational parameters that affect bioethanol production from microcrystalline cellulose were optimized. Under optimum conditions (pH 8.0, temperature 55 °C, inoculum size 4% (v/v) and 0.5% (w/v) substrate concentration), a maximum ethanol yield of 0.30 g ethanol/g cellulose consumed and 95.32% cellulose conversion was obtained. An inclusion of modest acetate concentration in the medium showed that carbon flux shifted away from lactate accompanied by 20% increase in ethanol production. It suggests that strain ATCC 31924 differed in its cellulose conversion efficacy and optimum pH requirements compared to the other reported strains of Clostridium thermocellum. The purified cellulosome of strain ATCC 31924 found to be rich in both cellulase and xylanase enzymes emphasizing the importance of this strain for the degradation of lignocellulosic biomass.
Collapse
Affiliation(s)
- Nisha Singh
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia; DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Anshu S Mathur
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Ravi P Gupta
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Colin J Barrow
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia
| | - Deepak Tuli
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Munish Puri
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia.
| |
Collapse
|
15
|
Choi J, Klingeman DM, Brown SD, Cox CD. The LacI family protein GlyR3 co-regulates the celC operon and manB in Clostridium thermocellum. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:163. [PMID: 28652864 PMCID: PMC5483248 DOI: 10.1186/s13068-017-0849-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/16/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Clostridium thermocellum utilizes a wide variety of free and cellulosomal cellulases and accessory enzymes to hydrolyze polysaccharides present in complex substrates. To date only a few studies have unveiled the details by which the expression of these cellulases are regulated. Recent studies have described the auto regulation of the celC operon and determined that the celC-glyR3-licA gene cluster and nearby manB-celT gene cluster are co-transcribed as polycistronic mRNA. RESULTS In this paper, we demonstrate that the GlyR3 protein mediates the regulation of manB. We first identify putative GlyR3 binding sites within or just upstream of the coding regions of manB and celT. Using an electrophoretic mobility shift assay (EMSA), we determined that a higher concentration of GlyR3 is required to effectively bind to the putative manB site in comparison to the celC site. Neither the putative celT site nor random DNA significantly binds GlyR3. While laminaribiose interfered with GlyR3 binding to the celC binding site, binding to the manB site was unaffected. In the presence of laminaribiose, in vivo transcription of the celC-glyR3-licA gene cluster increases, while manB expression is repressed, compared to in the absence of laminaribiose, consistent with the results from the EMSA. An in vitro transcription assay demonstrated that GlyR3 and laminaribiose interactions were responsible for the observed patters of in vivo transcription. CONCLUSIONS Together these results reveal a mechanism by which manB is expressed at low concentrations of GlyR3 but repressed at high concentrations. In this way, C. thermocellum is able to co-regulate both the celC and manB gene clusters in response to the availability of β-1,3-polysaccharides in its environment.
Collapse
Affiliation(s)
- Jinlyung Choi
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996 USA
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Dawn M. Klingeman
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Steven D. Brown
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Chris D. Cox
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996 USA
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 USA
| |
Collapse
|
16
|
Chen H, Huang R, Zhang YHP. Systematic comparison of co-expression of multiple recombinant thermophilic enzymes in Escherichia coli BL21(DE3). Appl Microbiol Biotechnol 2017; 101:4481-4493. [PMID: 28251267 DOI: 10.1007/s00253-017-8206-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 01/08/2023]
Abstract
The precise control of multiple heterologous enzyme expression levels in one Escherichia coli strain is important for cascade biocatalysis, metabolic engineering, synthetic biology, natural product synthesis, and studies of complexed proteins. We systematically investigated the co-expression of up to four thermophilic enzymes (i.e., α-glucan phosphorylase (αGP), phosphoglucomutase (PGM), glucose 6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6PGDH)) in E. coli BL21(DE3) by adding T7 promoter or T7 terminator of each gene for multiple genes in tandem, changing gene alignment, and comparing one or two plasmid systems. It was found that the addition of T7 terminator after each gene was useful to decrease the influence of the upstream gene. The co-expression of the four enzymes in E. coli BL21(DE3) was demonstrated to generate two NADPH molecules from one glucose unit of maltodextrin, where NADPH was oxidized to convert xylose to xylitol. The best four-gene co-expression system was based on two plasmids (pET and pACYC) which harbored two genes. As a result, apparent enzymatic activities of the four enzymes were regulated to be at similar levels and the overall four-enzyme activity was the highest based on the formation of xylitol. This study provides useful information for the precise control of multi-enzyme-coordinated expression in E. coli BL21(DE3).
Collapse
Affiliation(s)
- Hui Chen
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA, 24061, USA
| | - Rui Huang
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA, 24061, USA
| | - Y-H Percival Zhang
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA, 24061, USA. .,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China.
| |
Collapse
|
17
|
Zhou J, Shao X, Olson DG, Murphy SJL, Tian L, Lynd LR. Determining the roles of the three alcohol dehydrogenases (AdhA, AdhB and AdhE) in Thermoanaerobacter ethanolicus during ethanol formation. J Ind Microbiol Biotechnol 2017; 44:745-757. [PMID: 28078513 DOI: 10.1007/s10295-016-1896-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/22/2016] [Indexed: 12/25/2022]
Abstract
Thermoanaerobacter ethanolicus is a promising candidate for biofuel production due to the broad range of substrates it can utilize and its high ethanol yield compared to other thermophilic bacteria, such as Clostridium thermocellum. Three alcohol dehydrogenases, AdhA, AdhB and AdhE, play key roles in ethanol formation. To study their physiological roles during ethanol formation, we deleted them separately and in combination. Previously, it has been thought that both AdhB and AdhE were bifunctional alcohol dehydrogenases. Here we show that AdhE has primarily acetyl-CoA reduction activity (ALDH) and almost no acetaldehyde reduction (ADH) activity, whereas AdhB has no ALDH activity and but high ADH activity. We found that AdhA and AdhB have similar patterns of activity. Interestingly, although deletion of both adhA and adhB reduced ethanol production, a single deletion of either one actually increased ethanol yields by 60-70%.
Collapse
Affiliation(s)
- Jilai Zhou
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Xiongjun Shao
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Sean Jean-Loup Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Liang Tian
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA. .,Bioenergy Science Center, Oak Ridge, TN, USA.
| |
Collapse
|
18
|
Mason PM, Stuckey DC. Biofilms, bubbles and boundary layers - A new approach to understanding cellulolysis in anaerobic and ruminant digestion. WATER RESEARCH 2016; 104:93-100. [PMID: 27518146 DOI: 10.1016/j.watres.2016.07.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 06/06/2023]
Abstract
Anaerobic digestion of plant biomass to hydrocarbons could play a major part in meeting the needs of a modern low carbon society, but the cost reductions needed to make it an economically viable technology have been slower to arrive than in other renewable technologies. This is notwithstanding the observation that ruminants carry out the rate limiting hydrolysis step up to 30 times faster than an AD plant, and that bio-mimicry of ruminants could be an important source of innovation. This paper examines a number of factors which may, by focusing emphasis on the physical and chemical environment within cellulolytic biofilms, help accelerate development in the arena. It examines the process of cellulolysis from the perspective of a bacterium attached within a biofilm to a piece of insoluble cellulosic substrate to illustrate the extent of chemical heterogeneity that exists in the film, and between the film and the supernatant, and how this might control the rate of cellulolysis. It suggests several strategies used by ruminants to manage this heterogeneity that may be significant contributors to their effectiveness, and could provide a useful guide to more effective anaerobic digestion.
Collapse
Affiliation(s)
- P Michael Mason
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK; Tropical Power Ltd., 58 Church Way, Oxford, OX4 4EF, UK.
| | - David C Stuckey
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| |
Collapse
|
19
|
Lo J, Olson DG, Murphy SJL, Tian L, Hon S, Lanahan A, Guss AM, Lynd LR. Engineering electron metabolism to increase ethanol production in Clostridium thermocellum. Metab Eng 2016; 39:71-79. [PMID: 27989806 DOI: 10.1016/j.ymben.2016.10.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/17/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
The NfnAB (NADH-dependent reduced ferredoxin: NADP+ oxidoreductase) and Rnf (ion-translocating reduced ferredoxin: NAD+ oxidoreductase) complexes are thought to catalyze electron transfer between reduced ferredoxin and NAD(P)+. Efficient electron flux is critical for engineering fuel production pathways, but little is known about the relative importance of these enzymes in vivo. In this study we investigate the importance of the NfnAB and Rnf complexes in Clostridium thermocellum for growth on cellobiose and Avicel using gene deletion, enzyme assays, and fermentation product analysis. The NfnAB complex does not seem to play a major role in metabolism, since deletion of nfnAB genes had little effect on the distribution of fermentation products. By contrast, the Rnf complex appears to play an important role in ethanol formation. Deletion of rnf genes resulted in a decrease in ethanol formation. Overexpression of rnf genes resulted in an increase in ethanol production of about 30%, but only in strains where the hydG hydrogenase maturation gene was also deleted.
Collapse
Affiliation(s)
- Jonathan Lo
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Sean Jean-Loup Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Liang Tian
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Shuen Hon
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Anthony Lanahan
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Adam M Guss
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA.
| |
Collapse
|
20
|
Thompson RA, Dahal S, Garcia S, Nookaew I, Trinh CT. Exploring complex cellular phenotypes and model-guided strain design with a novel genome-scale metabolic model of Clostridium thermocellum DSM 1313 implementing an adjustable cellulosome. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:194. [PMID: 27602057 PMCID: PMC5012057 DOI: 10.1186/s13068-016-0607-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/26/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND Clostridium thermocellum is a gram-positive thermophile that can directly convert lignocellulosic material into biofuels. The metabolism of C. thermocellum contains many branches and redundancies which limit biofuel production, and typical genetic techniques are time-consuming. Further, the genome sequence of a genetically tractable strain C. thermocellum DSM 1313 has been recently sequenced and annotated. Therefore, developing a comprehensive, predictive, genome-scale metabolic model of DSM 1313 is desired for elucidating its complex phenotypes and facilitating model-guided metabolic engineering. RESULTS We constructed a genome-scale metabolic model iAT601 for DSM 1313 using the KEGG database as a scaffold and an extensive literature review and bioinformatic analysis for model refinement. Next, we used several sets of experimental data to train the model, e.g., estimation of the ATP requirement for growth-associated maintenance (13.5 mmol ATP/g DCW/h) and cellulosome synthesis (57 mmol ATP/g cellulosome/h). Using our tuned model, we investigated the effect of cellodextrin lengths on cell yields, and could predict in silico experimentally observed differences in cell yield based on which cellodextrin species is assimilated. We further employed our tuned model to analyze the experimentally observed differences in fermentation profiles (i.e., the ethanol to acetate ratio) between cellobiose- and cellulose-grown cultures and infer regulatory mechanisms to explain the phenotypic differences. Finally, we used the model to design over 250 genetic modification strategies with the potential to optimize ethanol production, 6155 for hydrogen production, and 28 for isobutanol production. CONCLUSIONS Our developed genome-scale model iAT601 is capable of accurately predicting complex cellular phenotypes under a variety of conditions and serves as a high-quality platform for model-guided strain design and metabolic engineering to produce industrial biofuels and chemicals of interest.
Collapse
Affiliation(s)
- R. Adam Thompson
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sanjeev Dahal
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sergio Garcia
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
| | - Intawat Nookaew
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Biomedical Informatics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205 USA
| | - Cong T. Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
| |
Collapse
|
21
|
Beri D, Olson DG, Holwerda EK, Lynd LR. Nicotinamide cofactor ratios in engineered strains of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum. FEMS Microbiol Lett 2016; 363:fnw091. [PMID: 27190292 DOI: 10.1093/femsle/fnw091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2016] [Indexed: 12/30/2022] Open
Abstract
Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are bacteria under investigation for production of biofuels from plant biomass. Thermoanaerobacterium saccharolyticum has been engineered to produce ethanol at high yield (>90% of theoretical) and titer (>70 g/l). Efforts to engineer C. thermocellum have not, to date, been as successful, and efforts are underway to transfer the ethanol production pathway from T. saccharolyticum to C. thermocellum One potential challenge in transferring metabolic pathways is the possibility of incompatible levels of nicotinamide cofactors. These cofactors (NAD(+), NADH, NADP(+) and NADPH) and their oxidation state are important in the context of microbial redox metabolism. In this study we directly measured the concentrations and reduced oxidized ratios of these cofactors in a number of strains of C. thermocellum and T. saccharolyticum by using acid/base extraction and enzymatic assays. We found that cofactor ratios are maintained in a fairly narrow range, regardless of the metabolic network modifications considered. We have found that the ratios are similar in both organisms, which is a relevant observation in the context of transferring the T. saccharolyticum ethanol production pathway to C. thermocellum.
Collapse
Affiliation(s)
- Dhananjay Beri
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Evert K Holwerda
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| |
Collapse
|
22
|
Rojas-Rejón ÓA, Poggi-Varaldo HM, Ramos-Valdivia AC, Ponce-Noyola T, Cristiani-Urbina E, Martínez A, de la Torre M. Enzymatic saccharification of sugar cane bagasse by continuous xylanase and cellulase production from cellulomonas flavigena PR-22. Biotechnol Prog 2015; 32:321-6. [PMID: 26701152 DOI: 10.1002/btpr.2213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 12/03/2015] [Indexed: 11/08/2022]
Abstract
Cellulase (CMCase) and xylanase enzyme production and saccharification of sugar cane bagasse were coupled into two stages and named enzyme production and sugar cane bagasse saccharification. The performance of Cellulomonas flavigena (Cf) PR-22 cultured in a bubble column reactor (BCR) was compared to that in a stirred tank reactor (STR). Cells cultured in the BCR presented higher yields and productivity of both CMCase and xylanase activities than those grown in the STR configuration. A continuous culture with Cf PR-22 was run in the BCR using 1% alkali-pretreated sugar cane bagasse and mineral media, at dilution rates ranging from 0.04 to 0.22 1/h. The highest enzymatic productivity values were found at 0.08 1/h with 1846.4 ± 126.4 and 101.6 ± 5.6 U/L·h for xylanase and CMCase, respectively. Effluent from the BCR in steady state was transferred to an enzymatic reactor operated in fed-batch mode with an initial load of 75 g of pretreated sugar cane bagasse; saccharification was then performed in an STR at 55°C and 300 rpm for 90 h. The constant addition of fresh enzyme as well as the increase in time of contact with the substrate increased the total soluble sugar concentration 83% compared to the value obtained in a batch enzymatic reactor. This advantageous strategy may be used for industrial enzyme pretreatment and saccharification of lignocellulosic wastes to be used in bioethanol and chemicals production from lignocellulose. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:321-326, 2016.
Collapse
Affiliation(s)
- Óscar A Rojas-Rejón
- Departamento de Biotecnología y Bioingeniería, Centro De Investigación y De Estudios Avanzados del Instituto Politécnico Nacional, Zacatenco, DF, 07300, México
| | - Héctor M Poggi-Varaldo
- Departamento de Biotecnología y Bioingeniería, Centro De Investigación y De Estudios Avanzados del Instituto Politécnico Nacional, Zacatenco, DF, 07300, México
| | - Ana C Ramos-Valdivia
- Departamento de Biotecnología y Bioingeniería, Centro De Investigación y De Estudios Avanzados del Instituto Politécnico Nacional, Zacatenco, DF, 07300, México
| | - Teresa Ponce-Noyola
- Departamento de Biotecnología y Bioingeniería, Centro De Investigación y De Estudios Avanzados del Instituto Politécnico Nacional, Zacatenco, DF, 07300, México
| | - Eliseo Cristiani-Urbina
- Departamento de Ingeniería Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prolongación Carpio y Plan De Ayala, Santo Tomás, DF, 11340, México
| | - Alfredo Martínez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62250, México
| | - Mayra de la Torre
- Departamento de Ciencia de los Alimentos. Centro de Investigación en Alimentación y Desarrollo, Carretera La Victoria Km 0.6, Hermosillo, 83304, Sonora, México
| |
Collapse
|
23
|
Differences in biomass degradation between newly isolated environmental strains of Clostridium thermocellum and heterogeneity in the size of the cellulosomal scaffoldin. Syst Appl Microbiol 2015; 38:424-32. [DOI: 10.1016/j.syapm.2015.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/05/2015] [Accepted: 06/05/2015] [Indexed: 11/21/2022]
|
24
|
Sand A, Holwerda EK, Ruppertsberger NM, Maloney M, Olson DG, Nataf Y, Borovok I, Sonenshein AL, Bayer EA, Lamed R, Lynd LR, Shoham Y. Three cellulosomal xylanase genes inClostridium thermocellumare regulated by both vegetative SigA (σA) and alternative SigI6 (σI6) factors. FEBS Lett 2015; 589:3133-40. [DOI: 10.1016/j.febslet.2015.08.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 08/10/2015] [Accepted: 08/14/2015] [Indexed: 11/29/2022]
|
25
|
Development of a regulatable plasmid-based gene expression system for Clostridium thermocellum. Appl Microbiol Biotechnol 2015; 99:7589-99. [DOI: 10.1007/s00253-015-6610-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 04/07/2015] [Accepted: 04/15/2015] [Indexed: 01/31/2023]
|
26
|
Bruder M, Moo-Young M, Chung DA, Chou CP. Elimination of carbon catabolite repression in Clostridium acetobutylicum—a journey toward simultaneous use of xylose and glucose. Appl Microbiol Biotechnol 2015; 99:7579-88. [DOI: 10.1007/s00253-015-6611-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 04/09/2015] [Accepted: 04/12/2015] [Indexed: 10/23/2022]
|
27
|
Coculture of Staphylococcus aureus with Pseudomonas aeruginosa Drives S. aureus towards Fermentative Metabolism and Reduced Viability in a Cystic Fibrosis Model. J Bacteriol 2015; 197:2252-64. [PMID: 25917910 DOI: 10.1128/jb.00059-15] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 04/23/2015] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED The airways of patients with cystic fibrosis are colonized with diverse bacterial communities that change dynamically during pediatric years and early adulthood. Staphylococcus aureus is the most prevalent pathogen during early childhood, but during late teens and early adulthood, a shift in microbial composition occurs leading to Pseudomonas aeruginosa community predominance in ∼50% of adults. We developed a robust dual-bacterial in vitro coculture system of P. aeruginosa and S. aureus on monolayers of human bronchial epithelial cells homozygous for the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) mutation to better model the mechanisms of this interaction. We show that P. aeruginosa drives the S. aureus expression profile from that of aerobic respiration to fermentation. This shift is dependent on the production of both 2-heptyl-4-hydroxyquinoline N-oxide (HQNO) and siderophores by P. aeruginosa. Furthermore, S. aureus-produced lactate is a carbon source that P. aeruginosa preferentially consumes over medium-supplied glucose. We find that initially S. aureus and P. aeruginosa coexist; however, over extended coculture P. aeruginosa reduces S. aureus viability, also in an HQNO- and P. aeruginosa siderophore-dependent manner. Interestingly, S. aureus small-colony-variant (SCV) genetic mutant strains, which have defects in their electron transport chain, experience reduced killing by P. aeruginosa compared to their wild-type parent strains; thus, SCVs may provide a mechanism for persistence of S. aureus in the presence of P. aeruginosa. We propose that the mechanism of P. aeruginosa-mediated killing of S. aureus is multifactorial, requiring HQNO and P. aeruginosa siderophores as well as additional genetic, environmental, and nutritional factors. IMPORTANCE In individuals with cystic fibrosis, Staphylococcus aureus is the primary respiratory pathogen during childhood. During adulthood, Pseudomonas aeruginosa predominates and correlates with worse patient outcome. The mechanism(s) by which P. aeruginosa outcompetes or kills S. aureus is not well understood. We describe an in vitro dual-bacterial species coculture system on cystic fibrosis-derived airway cells, which models interactions relevant to patients with cystic fibrosis. Further, we show that molecules produced by P. aeruginosa additively induce a transition of S. aureus metabolism from aerobic respiration to fermentation and eventually lead to loss of S. aureus viability. Elucidating the molecular mechanisms of P. aeruginosa community predominance can provide new therapeutic targets and approaches to impede this microbial community transition and subsequent patient worsening.
Collapse
|
28
|
Zhou J, Olson DG, Lanahan AA, Tian L, Murphy SJL, Lo J, Lynd LR. Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:138. [PMID: 26379770 PMCID: PMC4570089 DOI: 10.1186/s13068-015-0304-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/03/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30-70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. RESULTS It was found that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. CONCLUSION PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.
Collapse
Affiliation(s)
- Jilai Zhou
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Daniel G Olson
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Anthony A Lanahan
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Liang Tian
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Sean Jean-Loup Murphy
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Jonathan Lo
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Lee R Lynd
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| |
Collapse
|
29
|
Wen Z, Wu M, Lin Y, Yang L, Lin J, Cen P. A novel strategy for sequential co-culture of Clostridium thermocellum and Clostridium beijerinckii to produce solvents from alkali extracted corn cobs. Process Biochem 2014. [DOI: 10.1016/j.procbio.2014.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
30
|
Yaniv O, Fichman G, Borovok I, Shoham Y, Bayer EA, Lamed R, Shimon LJW, Frolow F. Fine-structural variance of family 3 carbohydrate-binding modules as extracellular biomass-sensing components of Clostridium thermocellum anti-σI factors. ACTA ACUST UNITED AC 2014; 70:522-34. [PMID: 24531486 DOI: 10.1107/s139900471302926x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 10/23/2013] [Indexed: 11/11/2022]
Abstract
The anaerobic, thermophilic, cellulosome-producing bacterium Clostridium thermocellum relies on a variety of carbohydrate-active enzymes in order to efficiently break down complex carbohydrates into utilizable simple sugars. The regulation mechanism of the cellulosomal genes was unknown until recently, when genomic analysis revealed a set of putative operons in C. thermocellum that encode σI factors (i.e. alternative σ factors that control specialized regulon activation) and their cognate anti-σI factor (RsgI). These putative anti-σI-factor proteins have modules that are believed to be carbohydrate sensors. Three of these modules were crystallized and their three-dimensional structures were solved. The structures show a high overall degree of sequence and structural similarity to the cellulosomal family 3 carbohydrate-binding modules (CBM3s). The structures of the three carbohydrate sensors (RsgI-CBM3s) and a reference CBM3 are compared in the context of the structural determinants for the specificity of cellulose and complex carbohydrate binding. Fine structural variations among the RsgI-CBM3s appear to result in alternative substrate preferences for each of the sensors.
Collapse
Affiliation(s)
- Oren Yaniv
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Galit Fichman
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Yuval Shoham
- Department of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Linda J W Shimon
- Department of Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Felix Frolow
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| |
Collapse
|
31
|
Role of transcription and enzyme activities in redistribution of carbon and electron flux in response to N2 and H2 sparging of open-batch cultures of Clostridium thermocellum ATCC 27405. Appl Microbiol Biotechnol 2014; 98:2829-40. [DOI: 10.1007/s00253-013-5500-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 12/17/2022]
|
32
|
St Brice LA, Shao X, Izquierdo JA, Lynd LR. OPTIMIZATION OF AFFINITY DIGESTION FOR THE ISOLATION OF CELLULOSOMES FROMClostridium thermocellum. Prep Biochem Biotechnol 2013; 44:206-16. [DOI: 10.1080/10826068.2013.829494] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
33
|
Linville JL, Rodriguez M, Land M, Syed MH, Engle NL, Tschaplinski TJ, Mielenz JR, Cox CD. Industrial robustness: understanding the mechanism of tolerance for the Populus hydrolysate-tolerant mutant strain of Clostridium thermocellum. PLoS One 2013; 8:e78829. [PMID: 24205326 PMCID: PMC3804516 DOI: 10.1371/journal.pone.0078829] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 09/16/2013] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND An industrially robust microorganism that can efficiently degrade and convert lignocellulosic biomass into ethanol and next-generation fuels is required to economically produce future sustainable liquid transportation fuels. The anaerobic, thermophilic, cellulolytic bacterium Clostridium thermocellum is a candidate microorganism for such conversions but it, like many bacteria, is sensitive to potential toxic inhibitors developed in the liquid hydrolysate produced during biomass processing. Microbial processes leading to tolerance of these inhibitory compounds found in the pretreated biomass hydrolysate are likely complex and involve multiple genes. METHODOLOGY/PRINCIPAL FINDINGS In this study, we developed a 17.5% v/v Populus hydrolysate tolerant mutant strain of C. thermocellum by directed evolution. The genome of the wild type strain, six intermediate population samples and seven single colony isolates were sequenced to elucidate the mechanism of tolerance. Analysis of the 224 putative mutations revealed 73 high confidence mutations. A longitudinal analysis of the intermediate population samples, a pan-genomic analysis of the isolates, and a hotspot analysis revealed 24 core genes common to all seven isolates and 8 hotspots. Genetic mutations were matched with the observed phenotype through comparison of RNA expression levels during fermentation by the wild type strain and mutant isolate 6 in various concentrations of Populus hydrolysate (0%, 10%, and 17.5% v/v). CONCLUSION/SIGNIFICANCE The findings suggest that there are multiple mutations responsible for the Populus hydrolysate tolerant phenotype resulting in several simultaneous mechanisms of action, including increases in cellular repair, and altered energy metabolism. To date, this study provides the most comprehensive elucidation of the mechanism of tolerance to a pretreated biomass hydrolysate by C. thermocellum. These findings make important contributions to the development of industrially robust strains of consolidated bioprocessing microorganisms.
Collapse
Affiliation(s)
- Jessica L Linville
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee, United States of America ; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Wilson CM, Yang S, Rodriguez M, Ma Q, Johnson CM, Dice L, Xu Y, Brown SD. Clostridium thermocellum transcriptomic profiles after exposure to furfural or heat stress. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:131. [PMID: 24028713 PMCID: PMC3848806 DOI: 10.1186/1754-6834-6-131] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 09/04/2013] [Indexed: 05/23/2023]
Abstract
BACKGROUND The thermophilic anaerobe Clostridium thermocellum is a candidate consolidated bioprocessing (CBP) biocatalyst for cellulosic ethanol production. It is capable of both cellulose solubilization and its fermentation to produce lignocellulosic ethanol. Intolerance to stresses routinely encountered during industrial fermentations may hinder the commercial development of this organism. A previous C. thermocellum ethanol stress study showed that the largest transcriptomic response was in genes and proteins related to nitrogen uptake and metabolism. RESULTS In this study, C. thermocellum was grown to mid-exponential phase and treated with furfural or heat to a final concentration of 3 g.L-1 or 68°C respectively to investigate general and specific physiological and regulatory stress responses. Samples were taken at 10, 30, 60 and 120 min post-shock, and from untreated control fermentations, for transcriptomic analyses and fermentation product determinations and compared to a published dataset from an ethanol stress study. Urea uptake genes were induced following furfural stress, but not to the same extent as ethanol stress and transcription from these genes was largely unaffected by heat stress. The largest transcriptomic response to furfural stress was genes for sulfate transporter subunits and enzymes in the sulfate assimilatory pathway, although these genes were also affected late in the heat and ethanol stress responses. Lactate production was higher in furfural treated culture, although the lactate dehydrogenase gene was not differentially expressed under this condition. Other redox related genes such as a copy of the rex gene, a bifunctional acetaldehyde-CoA/alcohol dehydrogenase and adjacent genes did show lower expression after furfural stress compared to the control, heat and ethanol fermentation profiles. Heat stress induced expression from chaperone related genes and overlap was observed with the responses to the other stresses. This study suggests the involvement of C. thermocellum genes with functions in oxidative stress protection, electron transfer, detoxification, sulfur and nitrogen acquisition, and DNA repair mechanisms in its stress responses and the use of different regulatory networks to coordinate and control adaptation. CONCLUSIONS This study has identified C. thermocellum gene regulatory motifs and aspects of physiology and gene regulation for further study. The nexus between future systems biology studies and recently developed genetic tools for C. thermocellum offers the potential for more rapid strain development and for broader insights into this organism's physiology and regulation.
Collapse
Affiliation(s)
- Charlotte M Wilson
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Shihui Yang
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Present address: National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Miguel Rodriguez
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Qin Ma
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, Computational Systems Biology Laboratory, University of Georgia, Athens, GA 30602, USA
| | - Courtney M Johnson
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Lezlee Dice
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Ying Xu
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, Computational Systems Biology Laboratory, University of Georgia, Athens, GA 30602, USA
- College of Computer Science and Technology, Jilin University, Changchun, Jilin, China
| | - Steven D Brown
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831 TN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| |
Collapse
|
35
|
Xu C, Huang R, Teng L, Wang D, Hemme CL, Borovok I, He Q, Lamed R, Bayer EA, Zhou J, Xu J. Structure and regulation of the cellulose degradome in Clostridium cellulolyticum. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:73. [PMID: 23657055 PMCID: PMC3656788 DOI: 10.1186/1754-6834-6-73] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 05/01/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND Many bacteria efficiently degrade lignocellulose yet the underpinning genome-wide metabolic and regulatory networks remain elusive. Here we revealed the "cellulose degradome" for the model mesophilic cellulolytic bacterium Clostridium cellulolyticum ATCC 35319, via an integrated analysis of its complete genome, its transcriptomes under glucose, xylose, cellobiose, cellulose, xylan or corn stover and its extracellular proteomes under glucose, cellobiose or cellulose. RESULTS Proteins for core metabolic functions, environment sensing, gene regulation and polysaccharide metabolism were enriched in the cellulose degradome. Analysis of differentially expressed genes revealed a "core" set of 48 CAZymes required for degrading cellulose-containing substrates as well as an "accessory" set of 76 CAZymes required for specific non-cellulose substrates. Gene co-expression analysis suggested that Carbon Catabolite Repression (CCR) related regulators sense intracellular glycolytic intermediates and control the core CAZymes that mainly include cellulosomal components, whereas 11 sets of Two-Component Systems (TCSs) respond to availability of extracellular soluble sugars and respectively regulate most of the accessory CAZymes and associated transporters. Surprisingly, under glucose alone, the core cellulases were highly expressed at both transcript and protein levels. Furthermore, glucose enhanced cellulolysis in a dose-dependent manner, via inducing cellulase transcription at low concentrations. CONCLUSION A molecular model of cellulose degradome in C. cellulolyticum (Ccel) was proposed, which revealed the substrate-specificity of CAZymes and the transcriptional regulation of core cellulases by CCR where the glucose acts as a CCR inhibitor instead of a trigger. These features represent a distinct environment-sensing strategy for competing while collaborating for cellulose utilization, which can be exploited for process and genetic engineering of microbial cellulolysis.
Collapse
Affiliation(s)
- Chenggang Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Ranran Huang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Lin Teng
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Dongmei Wang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Christopher L Hemme
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Qiang He
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Jian Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| |
Collapse
|
36
|
van der Veen D, Lo J, Brown SD, Johnson CM, Tschaplinski TJ, Martin M, Engle NL, van den Berg RA, Argyros AD, Caiazza NC, Guss AM, Lynd LR. Characterization of Clostridium thermocellum strains with disrupted fermentation end-product pathways. J Ind Microbiol Biotechnol 2013; 40:725-34. [PMID: 23645383 DOI: 10.1007/s10295-013-1275-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 04/15/2013] [Indexed: 10/26/2022]
Abstract
Clostridium thermocellum is a thermophilic, cellulolytic anaerobe that is a candidate microorganism for industrial biofuels production. Strains with mutations in genes associated with production of L-lactate (Δldh) and/or acetate (Δpta) were characterized to gain insight into the intracellular processes that convert cellobiose to ethanol and other fermentation end-products. Cellobiose-grown cultures of the Δldh strain had identical biomass accumulation, fermentation end-products, transcription profile, and intracellular metabolite concentrations compared to its parent strain (DSM1313 Δhpt Δspo0A). The Δpta-deficient strain grew slower and had 30 % lower final biomass concentration compared to the parent strain, yet produced 75 % more ethanol. A Δldh Δpta double-mutant strain evolved for faster growth had a growth rate and ethanol yield comparable to the parent strain, whereas its biomass accumulation was comparable to Δpta. Free amino acids were secreted by all examined strains, with both Δpta strains secreting higher amounts of alanine, valine, isoleucine, proline, glutamine, and threonine. Valine concentration for Δldh Δpta reached 5 mM by the end of growth, or 2.7 % of the substrate carbon utilized. These secreted amino acid concentrations correlate with increased intracellular pyruvate concentrations, up to sixfold in the Δpta and 16-fold in the Δldh Δpta strain. We hypothesize that the deletions in fermentation end-product pathways result in an intracellular redox imbalance, which the organism attempts to relieve, in part by recycling NADP⁺ through increased production of amino acids.
Collapse
|
37
|
Abstract
Cofactor specificities of glycolytic enzymes in Clostridium thermocellum were studied with cellobiose-grown cells from batch cultures. Intracellular glucose was phosphorylated by glucokinase using GTP rather than ATP. Although phosphofructokinase typically uses ATP as a phosphoryl donor, we found only pyrophosphate (PPi)-linked activity. Phosphoglycerate kinase used both GDP and ADP as phosphoryl acceptors. In agreement with the absence of a pyruvate kinase sequence in the C. thermocellum genome, no activity of this enzyme could be detected. Also, the annotated pyruvate phosphate dikinase (ppdk) is not crucial for the generation of pyruvate from phosphoenolpyruvate (PEP), as deletion of the ppdk gene did not substantially change cellobiose fermentation. Instead pyruvate formation is likely to proceed via a malate shunt with GDP-linked PEP carboxykinase, NADH-linked malate dehydrogenase, and NADP-linked malic enzyme. High activities of these enzymes were detected in extracts of cellobiose-grown cells. Our results thus show that GTP is consumed while both GTP and ATP are produced in glycolysis of C. thermocellum. The requirement for PPi in this pathway can be satisfied only to a small extent by biosynthetic reactions, in contrast to what is generally assumed for a PPi-dependent glycolysis in anaerobic heterotrophs. Metabolic network analysis showed that most of the required PPi must be generated via ATP or GTP hydrolysis exclusive of that which happens during biosynthesis. Experimental proof for the necessity of an alternative mechanism of PPi generation was obtained by studying the glycolysis in washed-cell suspensions in which biosynthesis was absent. Under these conditions, cells still fermented cellobiose to ethanol.
Collapse
|
38
|
Abstract
Many microorganisms contain cellulases that are important for plant cell wall degradation and overall soil ecosystem functioning. At present, we have extensive biochemical knowledge of cellulases but little is known about the phylogenetic distribution of these enzymes. To address this, we analyzed the distribution of 21,985 genes encoding proteins related to cellulose utilization in 5,123 sequenced bacterial genomes. First, we identified the distribution of glycoside hydrolases involved in cellulose utilization and synthesis at different taxonomic levels, from the phylum to the strain. Cellulose degradation/utilization capabilities appeared in nearly all major groups and resulted in strains displaying various enzyme gene combinations. Potential cellulose degraders, having both cellulases and β-glucosidases, constituted 24% of all genomes whereas potential opportunistic strains, having β-glucosidases only, accounted for 56%. Finally, 20% of the bacteria have no relevant enzymes and do not rely on cellulose utilization. The latter group was primarily connected to specific bacterial lifestyles like autotrophy and parasitism. Cellulose degraders, as well as opportunists, have multiple enzymes with similar functions. However, the potential degraders systematically harbor about twice more β-glucosidases than their potential opportunistic relatives. Although scattered, the distribution of functional types, in bacterial lineages, is not random but mostly follows a Brownian motion evolution model. Degraders form clusters of relatives at the species level, whereas opportunists are clustered at the genus level. This information can form a mechanistic basis for the linking of changes in microbial community composition to soil ecosystem processes.
Collapse
|
39
|
Carere CR, Rydzak T, Verbeke TJ, Cicek N, Levin DB, Sparling R. Linking genome content to biofuel production yields: a meta-analysis of major catabolic pathways among select H2 and ethanol-producing bacteria. BMC Microbiol 2012; 12:295. [PMID: 23249097 PMCID: PMC3561251 DOI: 10.1186/1471-2180-12-295] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/12/2012] [Indexed: 12/16/2022] Open
Abstract
Background Fermentative bacteria offer the potential to convert lignocellulosic waste-streams into biofuels such as hydrogen (H2) and ethanol. Current fermentative H2 and ethanol yields, however, are below theoretical maxima, vary greatly among organisms, and depend on the extent of metabolic pathways utilized. For fermentative H2 and/or ethanol production to become practical, biofuel yields must be increased. We performed a comparative meta-analysis of (i) reported end-product yields, and (ii) genes encoding pyruvate metabolism and end-product synthesis pathways to identify suitable biomarkers for screening a microorganism’s potential of H2 and/or ethanol production, and to identify targets for metabolic engineering to improve biofuel yields. Our interest in H2 and/or ethanol optimization restricted our meta-analysis to organisms with sequenced genomes and limited branched end-product pathways. These included members of the Firmicutes, Euryarchaeota, and Thermotogae. Results Bioinformatic analysis revealed that the absence of genes encoding acetaldehyde dehydrogenase and bifunctional acetaldehyde/alcohol dehydrogenase (AdhE) in Caldicellulosiruptor, Thermococcus, Pyrococcus, and Thermotoga species coincide with high H2 yields and low ethanol production. Organisms containing genes (or activities) for both ethanol and H2 synthesis pathways (i.e. Caldanaerobacter subterraneus subsp. tengcongensis, Ethanoligenens harbinense, and Clostridium species) had relatively uniform mixed product patterns. The absence of hydrogenases in Geobacillus and Bacillus species did not confer high ethanol production, but rather high lactate production. Only Thermoanaerobacter pseudethanolicus produced relatively high ethanol and low H2 yields. This may be attributed to the presence of genes encoding proteins that promote NADH production. Lactate dehydrogenase and pyruvate:formate lyase are not conducive for ethanol and/or H2 production. While the type(s) of encoded hydrogenases appear to have little impact on H2 production in organisms that do not encode ethanol producing pathways, they do influence reduced end-product yields in those that do. Conclusions Here we show that composition of genes encoding pathways involved in pyruvate catabolism and end-product synthesis pathways can be used to approximate potential end-product distribution patterns. We have identified a number of genetic biomarkers for streamlining ethanol and H2 producing capabilities. By linking genome content, reaction thermodynamics, and end-product yields, we offer potential targets for optimization of either ethanol or H2 yields through metabolic engineering.
Collapse
Affiliation(s)
- Carlo R Carere
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
| | | | | | | | | | | |
Collapse
|
40
|
Anaerobic high-throughput cultivation method for isolation of thermophiles using biomass-derived substrates. Methods Mol Biol 2012; 908:153-68. [PMID: 22843398 DOI: 10.1007/978-1-61779-956-3_15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Flow cytometry (FCM) techniques have been developed for sorting mesophilic organisms, but the difficulty increases if the target microbes are thermophilic anaerobes. We demonstrate a reliable, high-throughput method of screening thermophilic anaerobic organisms using FCM and 96-well plates for growth on biomass-relevant substrates. The method was tested using the cellulolytic thermophiles Clostridium thermocellum (T(opt) = 55 °C), Caldicellulosiruptor obsidiansis (T(opt) = 78 °C) and the fermentative hyperthermophiles, Pyrococcus furiosus (T(opt) = 100 °C) and Thermotoga maritima (T(opt) = 80 °C). Multi-well plates were incubated at various temperatures for approximately 72-120 h and then tested for growth. Positive growth resulting from single cells sorted into individual wells containing an anaerobic medium was verified by OD(600). Depending on the growth substrate, up to 80 % of the wells contained viable cultures, which could be transferred to fresh media. This method was used to isolate thermophilic microbes from Rabbit Creek, Yellowstone National Park (YNP), Wyoming. Substrates for enrichment cultures including crystalline cellulose (Avicel), xylan (from Birchwood), pretreated switchgrass and Populus were used to cultivate organisms that may be of interest to lignocellulosic biofuel production.
Collapse
|
41
|
Role of the CipA scaffoldin protein in cellulose solubilization, as determined by targeted gene deletion and complementation in Clostridium thermocellum. J Bacteriol 2012. [PMID: 23204466 DOI: 10.1128/jb.02014-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The CipA scaffoldin protein plays a key role in the Clostridium thermocellum cellulosome. Previous studies have revealed that mutants deficient in binding or solubilizing cellulose also exhibit reduced expression of CipA. To confirm that CipA is, in fact, necessary for rapid solubilization of crystalline cellulose, the gene was deleted from the chromosome using targeted gene deletion technologies. The CipA deletion mutant exhibited a 100-fold reduction in cellulose solubilization rate, although it was eventually able to solubilize 80% of the 5 g/liter cellulose initially present. The deletion mutant was complemented by a copy of cipA expressed from a replicating plasmid. In this strain, Avicelase activity was restored, although the rate was 2-fold lower than that in the wild type and the duration of the lag phase was increased. The cipA coding sequence is located at the beginning of a gene cluster containing several other genes thought to be responsible for the structural organization of the cellulosome, including olpB, orf2p, and olpA. Tandem mass spectrometry revealed a 10-fold reduction in the expression of olpB, which may explain the lower growth rate. This deletion experiment adds further evidence that CipA plays a key role in cellulose solubilization by C. thermocellum, and it raises interesting questions about the differential roles of the anchor scaffoldin proteins OlpB, Orf2p, and SdbA.
Collapse
|
42
|
Burton E, Martin VJJ. Proteomic analysis of Clostridium thermocellum ATCC 27405 reveals the upregulation of an alternative transhydrogenase-malate pathway and nitrogen assimilation in cells grown on cellulose. Can J Microbiol 2012; 58:1378-88. [PMID: 23210995 DOI: 10.1139/cjm-2012-0412] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Clostridium thermocellum is a Gram-positive thermophilic anaerobic bacterium with the ability to directly convert cellulosic biomass into useful products such as ethanol and hydrogen. In this study, a quantitative comparative proteomic analysis of the organism was performed to identify proteins and biochemical pathways that are differentially utilized by the organism after growth on cellobiose or cellulose. The cytoplasmic and membrane proteomes of C. thermocellum grown on cellulose or cellobiose were quantitatively compared using a metabolic (15)N isotope labelling method in conjunction with nanoLC-ESI-MS/MS (liquid chromatography - electrospray ionization - tandem mass spectrometry). In total, 1255 proteins were identified in the study, and 129 of those were able to have their relative abundance per cell compared in at least one cellular compartment in response to the substrate provided. This study reveals that cells grown on cellulose increase their abundance of phosphoenolpyruvate carboxykinase while decreasing the abundance of pyruvate dikinase and oxaloacetate decarboxylase, suggesting that the organism diverts carbon flow into a transhydrogenase-malate pathway that can increase the production of the biosynthetic intermediates NADPH and GTP. Glutamate dehydrogenase was also found to have increased abundance in cellulose-grown cells, suggesting that the assimilation of ammonia is upregulated in cells grown on the cellulosic substrates. The results illustrate a mechanism by which C. thermocellum can divert carbon into alternative pathways for the purpose of producing biosynthetic intermediates necessary to respond to growth on cellulose, including transhydrogenation of NADH to NADPH and increased nitrogen assimilation.
Collapse
Affiliation(s)
- Euan Burton
- Department of Biology, Concordia University, Montréal, QC H4B 1R6, Canada
| | | |
Collapse
|
43
|
Rydzak T, McQueen PD, Krokhin OV, Spicer V, Ezzati P, Dwivedi RC, Shamshurin D, Levin DB, Wilkins JA, Sparling R. Proteomic analysis of Clostridium thermocellum core metabolism: relative protein expression profiles and growth phase-dependent changes in protein expression. BMC Microbiol 2012; 12:214. [PMID: 22994686 PMCID: PMC3492117 DOI: 10.1186/1471-2180-12-214] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 09/11/2012] [Indexed: 01/21/2023] Open
Abstract
Background Clostridium thermocellum produces H2 and ethanol, as well as CO2, acetate, formate, and lactate, directly from cellulosic biomass. It is therefore an attractive model for biofuel production via consolidated bioprocessing. Optimization of end-product yields and titres is crucial for making biofuel production economically feasible. Relative protein expression profiles may provide targets for metabolic engineering, while understanding changes in protein expression and metabolism in response to carbon limitation, pH, and growth phase may aid in reactor optimization. We performed shotgun 2D-HPLC-MS/MS on closed-batch cellobiose-grown exponential phase C. thermocellum cell-free extracts to determine relative protein expression profiles of core metabolic proteins involved carbohydrate utilization, energy conservation, and end-product synthesis. iTRAQ (isobaric tag for relative and absolute quantitation) based protein quantitation was used to determine changes in core metabolic proteins in response to growth phase. Results Relative abundance profiles revealed differential levels of putative enzymes capable of catalyzing parallel pathways. The majority of proteins involved in pyruvate catabolism and end-product synthesis were detected with high abundance, with the exception of aldehyde dehydrogenase, ferredoxin-dependent Ech-type [NiFe]-hydrogenase, and RNF-type NADH:ferredoxin oxidoreductase. Using 4-plex 2D-HPLC-MS/MS, 24% of the 144 core metabolism proteins detected demonstrated moderate changes in expression during transition from exponential to stationary phase. Notably, proteins involved in pyruvate synthesis decreased in stationary phase, whereas proteins involved in glycogen metabolism, pyruvate catabolism, and end-product synthesis increased in stationary phase. Several proteins that may directly dictate end-product synthesis patterns, including pyruvate:ferredoxin oxidoreductases, alcohol dehydrogenases, and a putative bifurcating hydrogenase, demonstrated differential expression during transition from exponential to stationary phase. Conclusions Relative expression profiles demonstrate which proteins are likely utilized in carbohydrate utilization and end-product synthesis and suggest that H2 synthesis occurs via bifurcating hydrogenases while ethanol synthesis is predominantly catalyzed by a bifunctional aldehyde/alcohol dehydrogenase. Differences in expression profiles of core metabolic proteins in response to growth phase may dictate carbon and electron flux towards energy storage compounds and end-products. Combined knowledge of relative protein expression levels and their changes in response to physiological conditions may aid in targeted metabolic engineering strategies and optimization of fermentation conditions for improvement of biofuels production.
Collapse
Affiliation(s)
- Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Tschaplinski TJ, Standaert RF, Engle NL, Martin MZ, Sangha AK, Parks JM, Smith JC, Samuel R, Jiang N, Pu Y, Ragauskas AJ, Hamilton CY, Fu C, Wang ZY, Davison BH, Dixon RA, Mielenz JR. Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:71. [PMID: 22998926 PMCID: PMC3524654 DOI: 10.1186/1754-6834-5-71] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 09/05/2012] [Indexed: 05/02/2023]
Abstract
UNLABELLED BACKGROUND Down-regulation of the caffeic acid 3-O-methyltransferase EC 2.1.1.68 (COMT) gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum) resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycosyl hydrolases from an added enzyme preparation and from Clostridium thermocellum. Fermentation of both wild-type and transgenic switchgrass after milder hot water pretreatment with no water washing showed that only the transgenic switchgrass inhibited C. thermocellum. Gas chromatography-mass spectrometry (GCMS)-based metabolomics were undertaken on cell wall aqueous extracts to determine the nature of the microbial inhibitors. RESULTS GCMS confirmed the increased concentration of a number of phenolic acids and aldehydes that are known inhibitors of microbial fermentation. Metabolomic analyses of the transgenic biomass additionally revealed the presence of a novel monolignol-like metabolite, identified as trans-3, 4-dimethoxy-5-hydroxycinnamyl alcohol (iso-sinapyl alcohol) in both non-pretreated, as well as hot water pretreated samples. iso-Sinapyl alcohol and its glucoside were subsequently generated by organic synthesis and the identity of natural and synthetic materials were confirmed by mass spectrometric and NMR analyses. The additional novel presence of iso-sinapic acid, iso-sinapyl aldehyde, and iso-syringin suggest the increased activity of a para-methyltransferase, concomitant with the reduced COMT activity, a strict meta-methyltransferase. Quantum chemical calculations were used to predict the most likely homodimeric lignans generated from dehydration reactions, but these products were not evident in plant samples. CONCLUSIONS Down-regulation of COMT activity in switchgrass resulted in the accumulation of previously undetected metabolites resembling sinapyl alcohol and its related metabolites, but that are derived from para-methylation of 5-hydroxyconiferyl alcohol, and related precursors and products; the accumulation of which suggests altered metabolism of 5-hydroxyconiferyl alcohol in switchgrass. Given that there was no indication that iso-sinapyl alcohol was integrated in cell walls, it is considered a monolignol analog. Diversion of substrates from sinapyl alcohol to free iso-sinapyl alcohol, its glucoside, and associated upstream lignin pathway changes, including increased phenolic aldehydes and acids, are together associated with more facile cell wall deconstruction, and to the observed inhibitory effect on microbial growth. However, iso-sinapyl alcohol and iso-sinapic acid, added separately to media, were not inhibitory to C. thermocellum cultures.
Collapse
Affiliation(s)
- Timothy J Tschaplinski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Robert F Standaert
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
- Department of Biochemistry and Molecular & Cellular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Nancy L Engle
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Madhavi Z Martin
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Amandeep K Sangha
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
- Department of Biochemistry and Molecular & Cellular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jerry M Parks
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Jeremy C Smith
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
- Department of Biochemistry and Molecular & Cellular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Reichel Samuel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Nan Jiang
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Yunqiao Pu
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Arthur J Ragauskas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Choo Y Hamilton
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Chunxiang Fu
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Zeng-Yu Wang
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Brian H Davison
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Richard A Dixon
- Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| | - Jonathan R Mielenz
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6341, USA
- BioEnergy Science Center, Oak Ridge, TN 38731, USA
| |
Collapse
|
45
|
Yang S, Giannone RJ, Dice L, Yang ZK, Engle NL, Tschaplinski TJ, Hettich RL, Brown SD. Clostridium thermocellum ATCC27405 transcriptomic, metabolomic and proteomic profiles after ethanol stress. BMC Genomics 2012; 13:336. [PMID: 22823947 PMCID: PMC3478167 DOI: 10.1186/1471-2164-13-336] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 07/01/2012] [Indexed: 01/12/2023] Open
Abstract
Background Clostridium thermocellum is a candidate consolidated bioprocessing biocatalyst, which is a microorganism that expresses enzymes for both cellulose hydrolysis and its fermentation to produce fuels such as lignocellulosic ethanol. However, C. thermocellum is relatively sensitive to ethanol compared to ethanologenic microorganisms such as yeast and Zymomonas mobilis that are used in industrial fermentations but do not possess native enzymes for industrial cellulose hydrolysis. Results In this study, C. thermocellum was grown to mid-exponential phase and then treated with ethanol to a final concentration of 3.9 g/L to investigate its physiological and regulatory responses to ethanol stress. Samples were taken pre-shock and 2, 12, 30, 60, 120, and 240 min post-shock, and from untreated control fermentations for systems biology analyses. Cell growth was arrested by ethanol supplementation with intracellular accumulation of carbon sources such as cellobiose, and sugar phosphates, including fructose-6-phosphate and glucose-6-phosphate. The largest response of C. thermocellum to ethanol shock treatment was in genes and proteins related to nitrogen uptake and metabolism, which is likely important for redirecting the cells physiology to overcome inhibition and allow growth to resume. Conclusion This study suggests possible avenues for metabolic engineering and provides comprehensive, integrated systems biology datasets that will be useful for future metabolic modeling and strain development endeavors.
Collapse
Affiliation(s)
- Shihui Yang
- Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, USA
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Assessment of the biomass hydrolysis potential in bacterial isolates from a volcanic environment: biosynthesis of the corresponding activities. World J Microbiol Biotechnol 2012; 28:2889-902. [DOI: 10.1007/s11274-012-1100-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 06/05/2012] [Indexed: 11/25/2022]
|
47
|
Holwerda EK, Hirst KD, Lynd LR. A defined growth medium with very low background carbon for culturing Clostridium thermocellum. ACTA ACUST UNITED AC 2012; 39:943-7. [DOI: 10.1007/s10295-012-1091-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/14/2012] [Indexed: 11/29/2022]
Abstract
Abstract
A growth medium was developed for cultivation of Clostridium thermocellum ATCC 27405 in which “background” carbon present in buffers, reducing agents, chelating agents, and growth factors was a small fraction of the carbon present in the primary growth substrate. Background carbon was 1.6% of primary substrate carbon in the low-carbon (LC) medium, whereas it accounts for at least 40% in previously reported media. Fermentation of cellulose in LC medium was quite similar to Medium for Thermophilic Clostridia (MTC), a commonly used growth medium that contains background carbon at 88% of primary substrate carbon. Of particular note, we found that the organism can readily be cultivated by eliminating some components, lowering the concentrations of others, and employing a tenfold lower concentration of reducing agent. As such, we were able to reduce the amount of background carbon 55-fold compared to MTC medium while reaching the same cell biomass concentration. The final mass ratios of the products acetate:ethanol:formate were 5:3.9:1 for MTC and 4.1:1.5:1 for LC medium. LC medium is expected to facilitate metabolic studies involving identification and quantification of extracellular metabolites. In addition, this medium is expected to be useful in studies of cellulose utilization by anaerobic enrichment cultures obtained from environmental inocula, and in particular to diminish complications arising from metabolism of carbon-containing compounds other than cellulose. Finally, LC medium provides a starting point for industrial growth media development.
Collapse
Affiliation(s)
- Evert K Holwerda
- grid.254880.3 0000000121792404 Thayer School of Engineering at Dartmouth College 8000 Cummings Hall 03755 Hanover NH USA
| | - Kyle D Hirst
- grid.254880.3 0000000121792404 Thayer School of Engineering at Dartmouth College 8000 Cummings Hall 03755 Hanover NH USA
| | - Lee R Lynd
- grid.254880.3 0000000121792404 Thayer School of Engineering at Dartmouth College 8000 Cummings Hall 03755 Hanover NH USA
| |
Collapse
|
48
|
Tracy BP, Jones SW, Fast AG, Indurthi DC, Papoutsakis ET. Clostridia: the importance of their exceptional substrate and metabolite diversity for biofuel and biorefinery applications. Curr Opin Biotechnol 2012; 23:364-81. [DOI: 10.1016/j.copbio.2011.10.008] [Citation(s) in RCA: 263] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/06/2011] [Accepted: 10/20/2011] [Indexed: 12/19/2022]
|
49
|
Bianchetti CM, Elsen NL, Fox BG, Phillips GN. Structure of cellobiose phosphorylase from Clostridium thermocellum in complex with phosphate. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1345-9. [PMID: 22102229 PMCID: PMC3212448 DOI: 10.1107/s1744309111032660] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/11/2011] [Indexed: 11/10/2022]
Abstract
Clostridium thermocellum is a cellulosome-producing bacterium that is able to efficiently degrade and utilize cellulose as a sole carbon source. Cellobiose phosphorylase (CBP) plays a critical role in cellulose degradation by catalyzing the reversible phosphate-dependent hydrolysis of cellobiose, the major product of cellulose degradation, into α-D-glucose 1-phosphate and D-glucose. CBP from C. thermocellum is a modular enzyme composed of four domains [N-terminal domain, helical linker, (α/α)(6)-barrel domain and C-terminal domain] and is a member of glycoside hydrolase family 94. The 2.4 Å resolution X-ray crystal structure of C. thermocellum CBP reveals the residues involved in coordinating the catalytic phosphate as well as the residues that are likely to be involved in substrate binding and discrimination.
Collapse
Affiliation(s)
- Christopher M. Bianchetti
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Nathaniel L. Elsen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Brian G. Fox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - George N. Phillips
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| |
Collapse
|
50
|
Wang ZW, Lee SH, Elkins JG, Morrell-Falvey JL. fSpatial and temporal dynamics of cellulose degradation and biofilm formation by Caldicellulosiruptor obsidiansis and Clostridium thermocellum. AMB Express 2011; 1:30. [PMID: 21982458 PMCID: PMC3222322 DOI: 10.1186/2191-0855-1-30] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 10/07/2011] [Indexed: 11/23/2022] Open
Abstract
Cellulose degradation is one of the major bottlenecks of a consolidated bioprocess that employs cellulolytic bacterial cells as catalysts to produce biofuels from cellulosic biomass. In this study, we investigated the spatial and temporal dynamics of cellulose degradation by Caldicellulosiruptfor obsidiansis, which does not produce cellulosomes, and Clostridium thermocellum, which does produce cellulosomes. Results showed that the degradation of either regenerated or natural cellulose was synchronized with biofilm formation, a process characterized by the formation and fusion of numerous crater-like depressions on the cellulose surface. In addition, the dynamics of biofilm formation were similar in both bacteria, regardless of cellulosome production. Only the areas of cellulose surface colonized by microbes were significantly degraded, highlighting the essential role of the cellulolytic biofilm in cellulose utilization. After initial attachment, the microbial biofilm structure remained thin, uniform and dense throughout the experiment. A cellular automaton model, constructed under the assumption that the attached cells divide and produce daughter cells that contribute to the hydrolysis of the adjacent cellulose, can largely simulate the observed process of biofilm formation and cellulose degradation. This study presents a model, based on direct observation, correlating cellulolytic biofilm formation with cellulose degradation.
Collapse
Affiliation(s)
- Zhi-Wu Wang
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Seung-Hwan Lee
- National Institute of Advanced Industrial Science and Technology, Biomass Technology Research Center, Hiroshima, Japan
| | - James G Elkins
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jennifer L Morrell-Falvey
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| |
Collapse
|