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Chen J, Lin L, Tu Q, Peng Q, Wang X, Liang C, Zhou J, Yu X. Metagenomic-based discovery and comparison of the lignin degrading potential of microbiomes in aquatic and terrestrial ecosystems via the LCdb database. Mol Ecol Resour 2024; 24:e13950. [PMID: 38567644 DOI: 10.1111/1755-0998.13950] [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: 10/21/2023] [Revised: 02/05/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
Lignin, as an abundant organic carbon, plays a vital role in the global carbon cycle. However, our understanding of the global lignin-degrading microbiome remains elusive. The greatest barrier has been absence of a comprehensive and accurate functional gene database. Here, we first developed a curated functional gene database (LCdb) for metagenomic profiling of lignin degrading microbial consortia. Via the LCdb, we draw a clear picture describing the global biogeography of communities with lignin-degrading potential. They exhibit clear niche differentiation at the levels of taxonomy and functional traits. The terrestrial microbiomes showed the highest diversity, yet the lowest correlations. In particular, there were few correlations between genes involved in aerobic and anaerobic degradation pathways, showing a clear functional redundancy property. In contrast, enhanced correlations, especially closer inter-connections between anaerobic and aerobic groups, were observed in aquatic consortia in response to the lower diversity. Specifically, dypB and dypA, are widespread on Earth, indicating their essential roles in lignin depolymerization. Estuarine and marine consortia featured the laccase and mnsod genes, respectively. Notably, the roles of archaea in lignin degradation were revealed in marine ecosystems. Environmental factors strongly influenced functional traits, but weakly shaped taxonomic groups. Null mode analysis further verified that composition of functional traits was deterministic, while taxonomic composition was highly stochastic, demonstrating that the environment selects functional genes rather than taxonomic groups. Our study not only develops a useful tool to study lignin degrading microbial communities via metagenome sequencing but also advances our understanding of ecological traits of these global microbiomes.
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Affiliation(s)
- Jiyu Chen
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Lu Lin
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Qichao Tu
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Qiannan Peng
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Xiaopeng Wang
- Key Laboratory of Applied Marine Biotechnology, Ministry of Education, Ningbo University, Ningbo, China
| | - Congying Liang
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Jiayin Zhou
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Xiaoli Yu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou, China
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2
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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.
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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
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3
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Fiamenghi MB, Prodonoff JS, Borelli G, Carazzolle MF, Pereira GAG, José J. Comparative genomics reveals probable adaptations for xylose use in Thermoanaerobacterium saccharolyticum. Extremophiles 2024; 28:9. [PMID: 38190047 DOI: 10.1007/s00792-023-01327-x] [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: 06/06/2023] [Accepted: 11/28/2023] [Indexed: 01/09/2024]
Abstract
Second-generation ethanol, a promising biofuel for reducing greenhouse gas emissions, faces challenges due to the inefficient metabolism of xylose, a pentose sugar. Overcoming this hurdle requires exploration of genes, pathways, and organisms capable of fermenting xylose. Thermoanaerobacterium saccharolyticum is an organism capable of naturally fermenting compounds of industrial interest, such as xylose, and understanding evolutionary adaptations may help to bring novel genes and information that can be used for industrial yeast, increasing production of current bio-platforms. This study presents a deep evolutionary study of members of the firmicutes clade, focusing on adaptations in Thermoanaerobacterium saccharolyticum that may be related to overall fermentation metabolism, especially for xylose fermentation. One highlight is the finding of positive selection on a xylose-binding protein of the xylFGH operon, close to the annotated sugar binding site, with this protein already being found to be expressed in xylose fermenting conditions in a previous study. Results from this study can serve as basis for searching for candidate genes to use in industrial strains or to improve Thermoanaerobacterium saccharolyticum as a new microbial cell factory, which may help to solve current problems found in the biofuels' industry.
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Affiliation(s)
- Mateus Bernabe Fiamenghi
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil
| | - Juliana Silveira Prodonoff
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil
| | - Guilherme Borelli
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil
| | - Marcelo Falsarella Carazzolle
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil
| | - Gonçalo Amarante Guimaraes Pereira
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil.
| | - Juliana José
- Laboratory of Genomics and bioEnergy (LGE), Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, UNICAMP, Campinas, São Paulo, Brazil
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4
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Le Y, Sun J. CRISPR/Cas genome editing systems in thermophiles: Current status, associated challenges, and future perspectives. ADVANCES IN APPLIED MICROBIOLOGY 2022; 118:1-30. [PMID: 35461662 DOI: 10.1016/bs.aambs.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Thermophiles, offering an attractive and unique platform for a broad range of applications in biofuels and environment protections, have received a significant attention and growing interest from academy and industry. However, the exploration and exploitation of thermophilic organisms have been hampered by the lack of a powerful genome manipulation tool to improve production efficiency. At current, the clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/CRISPR associated (Cas) system has been successfully exploited as a competent, simplistic, and powerful tool for genome engineering both in eukaryotes and prokaryotes. Indeed, with the significant efforts made in recent years, some thermostable Cas9 proteins have been well identified and characterized and further, some thermostable Cas9-based editing tools have been successfully established in some representative obligate thermophiles. In this regard, we reviewed the current status and its progress in CRISPR/Cas-based genome editing system towards a variety of thermophilic organisms. Despite the potentials of these progresses, multiple factors/barriers still have to be overcome and optimized for improving its editing efficiency in thermophiles. Some insights into the roles of thermostable CRISPR/Cas technologies for the metabolic engineering of thermophiles as a thermophilic microbial cell factory were also fully analyzed and discussed.
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Affiliation(s)
- Yilin Le
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
| | - Jianzhong Sun
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
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5
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Centeno-Leija S, Espinosa-Barrera L, Velazquez-Cruz B, Cárdenas-Conejo Y, Virgen-Ortíz R, Valencia-Cruz G, Saenz RA, Marín-Tovar Y, Gómez-Manzo S, Hernández-Ochoa B, Rocha-Ramirez LM, Zataraín-Palacios R, Osuna-Castro JA, López-Munguía A, Serrano-Posada H. Mining for novel cyclomaltodextrin glucanotransferases unravels the carbohydrate metabolism pathway via cyclodextrins in Thermoanaerobacterales. Sci Rep 2022; 12:730. [PMID: 35031648 PMCID: PMC8760340 DOI: 10.1038/s41598-021-04569-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/20/2021] [Indexed: 11/21/2022] Open
Abstract
Carbohydrate metabolism via cyclodextrins (CM-CD) is an uncommon starch-converting pathway that thoroughly depends on extracellular cyclomaltodextrin glucanotransferases (CGTases) to transform the surrounding starch substrate to α-(1,4)-linked oligosaccharides and cyclodextrins (CDs). The CM-CD pathway has emerged as a convenient microbial adaptation to thrive under extreme temperatures, as CDs are functional amphipathic toroids with higher heat-resistant values than linear dextrins. Nevertheless, although the CM-CD pathway has been described in a few mesophilic bacteria and archaea, it remains obscure in extremely thermophilic prokaryotes (Topt ≥ 70 °C). Here, a new monophyletic group of CGTases with an exceptional three-domain ABC architecture was detected by (meta)genome mining of extremely thermophilic Thermoanaerobacterales living in a wide variety of hot starch-poor environments on Earth. Functional studies of a representative member, CldA, showed a maximum activity in a thermoacidophilic range (pH 4.0 and 80 °C) with remarkable product diversification that yielded a mixture of α:β:γ-CDs (34:62:4) from soluble starch, as well as G3-G7 linear dextrins and fermentable sugars as the primary products. Together, comparative genomics and predictive functional analysis, combined with data of the functionally characterized key proteins of the gene clusters encoding CGTases, revealed the CM-CD pathway in Thermoanaerobacterales and showed that it is involved in the synthesis, transportation, degradation, and metabolic assimilation of CDs.
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Affiliation(s)
- Sara Centeno-Leija
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico.
| | - Laura Espinosa-Barrera
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Beatriz Velazquez-Cruz
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Yair Cárdenas-Conejo
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Raúl Virgen-Ortíz
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Georgina Valencia-Cruz
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Avenida 25 de julio 965, Colonia Villa de San Sebastián, 28045, Colima, Colima, Mexico
| | - Roberto A Saenz
- Facultad de Ciencias, Universidad de Colima, Bernal Díaz del Castillo 340, 28045, Colima, Colima, Mexico
| | - Yerli Marín-Tovar
- Laboratorio de Bioquímica Estructural, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210, Cuernavaca, Mexico
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, 04530, Mexico City, Mexico
| | - Beatriz Hernández-Ochoa
- Laboratorio de Inmunoquímica y Biología Celular, Hospital Infantil de México Federico Gómez, Secretaría de Salud, 06720, Mexico City, Mexico
| | - Luz María Rocha-Ramirez
- Unidad de Investigación en Enfermedades Infecciosas, Hospital Infantil de México Federico Gómez, Dr. Márquez No. 162, Colonia Doctores, 06720, Delegación Cuauhtémoc, Mexico
| | - Rocío Zataraín-Palacios
- Escuela de Medicina General, Universidad José Martí, Bosques del Decán 351, 28089, Colima, Colima, México
| | - Juan A Osuna-Castro
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad de Colima, Autopista Colima-Manzanillo, 28100, Tecomán, Colima, Mexico
| | - Agustín López-Munguía
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210, Cuernavaca, Morelos, Mexico
| | - Hugo Serrano-Posada
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico.
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6
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Liang J, Roberts A, van Kranenburg R, Bolhuis A, Leak DJ. Relaxed control of sugar utilization in Parageobacillus thermoglucosidasius DSM 2542. Microbiol Res 2021; 256:126957. [PMID: 35032723 DOI: 10.1016/j.micres.2021.126957] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/22/2021] [Accepted: 12/27/2021] [Indexed: 01/08/2023]
Abstract
Though carbon catabolite repression (CCR) has been intensively studied in some more characterised organisms, there is a lack of information of CCR in thermophiles. In this work, CCR in the thermophile, Parageobacillus thermoglucosidasius DSM 2542 has been studied during growth on pentose sugars in the presence of glucose. Physiological studies under fermentative conditions revealed a loosely controlled CCR when DSM 2542 was grown in minimal medium supplemented with a mixture of glucose and xylose. This atypical CCR pattern was also confirmed by studying xylose isomerase expression level by qRT-PCR. Fortuitously, the pheB gene, which encodes catechol 2, 3-dioxygenase was found to have a cre site highly similar to the consensus catabolite-responsive element (cre) at its 3' end and was used to confirm that expression of pheB from a plasmid was under stringent CCR control. Bioinformatic analysis suggested that the CCR regulation of xylose metabolism in P. thermoglucosidasius DSM 2542 might occur primarily via control of expression of pentose transporter operons. Relaxed control of sugar utilization might reflect a lower affinity of the CcpA-HPr (Ser46-P) or CcpA-Crh (Ser46-P) complexes to the cre(s) in these operons.
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Affiliation(s)
- Jinghui Liang
- Department of Biology and Biochemistry, University of Bath, UK.
| | - Adam Roberts
- Department of Biology and Biochemistry, University of Bath, UK
| | - Richard van Kranenburg
- Laboratory of Microbiology, Wageningen University, The Netherlands; Corbion, Arkelsedijk 46, 4206 AC, Gorinchem, The Netherlands
| | - Albert Bolhuis
- Department of Pharmacy and Pharmacology, University of Bath, UK
| | - David J Leak
- Department of Biology and Biochemistry, University of Bath, UK
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7
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Hitschler L, Nissen LS, Kuntz M, Basen M. Alcohol dehydrogenases AdhE and AdhB with broad substrate ranges are important enzymes for organic acid reduction in Thermoanaerobacter sp. strain X514. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:187. [PMID: 34563250 PMCID: PMC8466923 DOI: 10.1186/s13068-021-02038-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The industrial production of various alcohols from organic carbon compounds may be performed at high rates and with a low risk of contamination using thermophilic microorganisms as whole-cell catalysts. Thermoanaerobacter species that thrive around 50-75 °C not only perform fermentation of sugars to alcohols, but some also utilize different organic acids as electron acceptors, reducing them to their corresponding alcohols. RESULTS We purified AdhE as the major NADH- and AdhB as the major NADPH-dependent alcohol dehydrogenase (ADH) from the cell extract of the organic acid-reducing Thermoanaerobacter sp. strain X514. Both enzymes were present in high amounts during growth on glucose with and without isobutyrate, had broad substrate spectra including different aldehydes, with high affinities (< 1 mM) for acetaldehyde and for NADH (AdhE) or NADPH (AdhB). Both enzymes were highly thermostable at the physiological temperature of alcohol production. In addition to AdhE and AdhB, we identified two abundant AdhA-type ADHs based on their genes, which were recombinantly produced and biochemically characterized. The other five ADHs encoded in the genome were only expressed at low levels. CONCLUSIONS According to their biochemical and kinetic properties, AdhE and AdhB are most important for ethanol formation from sugar and reduction of organic acids to alcohols, while the role of the two AdhA-type enzymes is less clear. AdhE is the only abundant aldehyde dehydrogenase for the acetyl-CoA reduction to aldehydes, however, acid reduction may also proceed directly by aldehyde:ferredoxin oxidoreductase. The role of the latter in bio-alcohol formation from sugar and in organic acid reduction needs to be elucidated in future studies.
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Affiliation(s)
- Lisa Hitschler
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue Str. 9, 60438, Frankfurt/Main, Germany
- Department of Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany
| | - Laura Sofie Nissen
- Microbiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein Str. 3, 18059, Rostock, Germany
| | - Michelle Kuntz
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue Str. 9, 60438, Frankfurt/Main, Germany
- Interfaculty Institute for Microbiology and Infection Medicine Tübingen, University of Tübingen, Auf der Morgenstelle 24, 72076, Tübingen, Germany
| | - Mirko Basen
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue Str. 9, 60438, Frankfurt/Main, Germany.
- Microbiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein Str. 3, 18059, Rostock, Germany.
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8
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Qu C, Zhang Y, Dai K, Fu H, Wang J. Metabolic engineering of Thermoanaerobacterium aotearoense SCUT27 for glucose and cellobiose co-utilization by identification and overexpression of the endogenous cellobiose operon. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2020.107922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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9
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Wang X, Lin L, Zhou J. Links among extracellular enzymes, lignin degradation and cell growth establish the models to identify marine lignin-utilizing bacteria. Environ Microbiol 2020; 23:160-173. [PMID: 33107668 DOI: 10.1111/1462-2920.15289] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 10/18/2020] [Indexed: 01/08/2023]
Abstract
A major conundrum in the isolation of prokaryotes from open environments is stochasticity. It is especially difficult to study low abundance groups where very little biological information exists, although single-cell genomics and metagenomics have alleviated some of this bottleneck. Here, we report an approach to capture lignin-utilizing bacteria by linking a physical model to actual organisms. Extracellular enzymes, lignin degradation and cell growth are crucial phenotypes of lignin-utilizing bacteria, but their interrelationships remain poorly understood. In this study, the phenotypes of bacteria isolated from in situ lignocellulose enrichment samples in coastal waters were traced and statistically analysed. It suggested cell growth, dye-decolorizing peroxidase (DyP) and reactive oxygen species (ROS) were significantly correlated with lignin degradation, exhibiting a genus-specific property. The established models enabled us to efficiently capture lignin-utilizing bacteria and rapidly evaluate lignin degradation for Bacillus and Vibrio strains. Through the model, we identified several previously unrecognized marine bacterial lignin degraders. Moreover, it demonstrated that the isolated marine lignin-utilizing bacteria employ a DyP-based system and ROS for lignin depolymerization, providing insights into the mechanism of marine bacterial lignin degradation. Our findings should have implications beyond the capture of lignin-utilizing bacteria, in the isolation of other microorganisms with as-yet-unknown molecular biomarkers.
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Affiliation(s)
- Xiaopeng Wang
- Institute of Marine Science and Technology, Shandong University, Qingdao, China.,Key Laboratory of Applied Marine Biotechnology, Ministry of Education, Ningbo University, Ningbo, China
| | - Lu Lin
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, and School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, OK, USA
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10
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Qu C, Chen L, Fu H, Wang J. Engineering Thermoanaerobacterium aotearoense SCUT27 with argR knockout for enhanced ethanol production from lignocellulosic hydrolysates. BIORESOURCE TECHNOLOGY 2020; 310:123435. [PMID: 32361198 DOI: 10.1016/j.biortech.2020.123435] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
Although Thermoanaerobacterium aotearoense SCUT27 (SCUT27) could co-utilize glucose and xylose, the presence of glucose still repressed xylose catabolism. Arginine repressors (ArgRs) were involved in several key metabolic pathways and might be the global regulator. In SCUT27, three genes (V518_0585; V518_1870; V518_1864) were annotated as argR and only the deficiency of argR1864 could greatly improve the co-utilization of glucose and xylose, due to the enhanced activity of xylose isomerase, xylulokinase and the higher energy level. The metabolic flux of SCUT27/ΔargR1864 indicated that new carbon distribution had been re-established and the ethanol yield had increased by 82.95%, strains growth and acetate yield improved by ~35.91% without detectable lactate for the poor activity of lactate dehydrogenase. The improved concentration of ATP and NAD(H) in SCUT27/ΔargR1864 provided more energy to respond the stress, which enabled the mutant the better cell viability to utilize lignocellulosic hydrolysates for enhanced ethanol formation.
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Affiliation(s)
- Chunyun Qu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Lili Chen
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; The State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China.
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11
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Lin L, Wang X, Cao L, Xu M. Lignin catabolic pathways reveal unique characteristics of dye-decolorizing peroxidases in Pseudomonas putida. Environ Microbiol 2020; 21:1847-1863. [PMID: 30882973 DOI: 10.1111/1462-2920.14593] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/11/2019] [Accepted: 03/15/2019] [Indexed: 11/28/2022]
Abstract
Lignin is one of the largest carbon reservoirs in the environment, playing an important role in the global carbon cycle. However, lignin degradation in bacteria, especially non-model organisms, has not been well characterized either enzymatically or genetically. Here, a lignin-degrading bacterial strain, Pseudomonas putida A514, was used as the research model. Genomic and proteomic analyses suggested that two B subfamily dye-decolorizing peroxidases (DypBs) were prominent in lignin depolymerization, while the classic O2 -dependent ring cleavage strategy was utilized in central pathways to catabolize lignin-derived aromatic compounds that were funnelled by peripheral pathways. These enzymes, together with a range of transporters, sequential and expression-dose dependent regulation and stress response systems coordinated for lignin metabolism. Catalytic assays indicated these DypBs show unique Mn2+ independent lignin depolymerization activity, while Mn2+ oxidation activity is absent. Furthermore, a high synergy between DypB enzymes and A514 cells was observed to promote cell growth (5 × 1012 cfus/ml) and lignin degradation (27%). This suggested DypBs are competitive lignin biocatalysts and pinpointed limited extracellular secretion capacity as the rate-limiting factor in bacterial lignin degradation. DypB production was, therefore, optimized in recombinant strains and a 14,141-fold increase in DypB activity (56,565 U/l) was achieved, providing novel insights for lignin bioconversion.
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Affiliation(s)
- Lu Lin
- Institute of Marine Science and Technology, Shandong University, Jinan, China.,Ocean College, Zhejiang University, Hangzhou, China
| | | | - Lanfang Cao
- Ocean College, Zhejiang University, Hangzhou, China
| | - Meiying Xu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangzhou, China
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12
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Metabolic Efficiency of Sugar Co-Metabolism and Phenol Degradation in Alicyclobacillus acidocaldarius for Improved Lignocellulose Processing. Processes (Basel) 2020. [DOI: 10.3390/pr8050502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Substrate availability plays a key role in dictating metabolic strategies. Most microorganisms consume carbon/energy sources in a sequential, preferential order. The presented study investigates metabolic strategies of Alicyclobacillus acidocaldarius, a thermoacidophilic bacterium that has been shown to co-utilize glucose and xylose, as well as degrade phenolic compounds. An existing metabolic model was expanded to include phenol degradation and was analyzed with both metabolic pathway and constraint-based analysis methods. Elementary flux mode analysis was used in conjunction with resource allocation theory to investigate ecologically optimal metabolic pathways for different carbon substrate combinations. Additionally, a dynamic version of flux balance analysis was used to generate time-resolved simulations of growth on phenol and xylose. Results showed that availability of xylose along with glucose did not predict enhanced growth efficiency beyond that of glucose alone, but did predict some differences in pathway utilization and byproduct profiles. In contrast, addition of phenol as a co-substrate with xylose predicted lower growth efficiency. Dynamic simulations predicted co-consumption of xylose and phenol in a similar pattern as previously reported experiments. Altogether, this work serves as a case study for combining both elementary flux mode and flux balance analyses to probe unique metabolic features, and also demonstrates the versatility of A. acidocaldarius for lignocellulosic biomass processing applications.
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Qu C, Chen L, Li Y, Fu H, Wang J. The redox-sensing transcriptional repressor Rex is important for regulating the products distribution in Thermoanaerobacterium aotearoense SCUT27. Appl Microbiol Biotechnol 2020; 104:5605-5617. [DOI: 10.1007/s00253-020-10554-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 01/06/2023]
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Nawab S, Wang N, Ma X, Huo YX. Genetic engineering of non-native hosts for 1-butanol production and its challenges: a review. Microb Cell Fact 2020; 19:79. [PMID: 32220254 PMCID: PMC7099781 DOI: 10.1186/s12934-020-01337-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 03/18/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Owing to the increase in energy consumption, fossil fuel resources are gradually depleting which has led to the growing environmental concerns; therefore, scientists are being urged to produce sustainable and ecofriendly fuels. Thus, there is a growing interest in the generation of biofuels from renewable energy resources using microbial fermentation. MAIN TEXT Butanol is a promising biofuel that can substitute for gasoline; unfortunately, natural microorganisms pose challenges for the economical production of 1-butanol at an industrial scale. The availability of genetic and molecular tools to engineer existing native pathways or create synthetic pathways have made non-native hosts a good choice for the production of 1-butanol from renewable resources. Non-native hosts have several distinct advantages, including using of cost-efficient feedstock, solvent tolerant and reduction of contamination risk. Therefore, engineering non-native hosts to produce biofuels is a promising approach towards achieving sustainability. This paper reviews the currently employed strategies and synthetic biology approaches used to produce 1-butanol in non-native hosts over the past few years. In addition, current challenges faced in using non-native hosts and the possible solutions that can help improve 1-butanol production are also discussed. CONCLUSION Non-native organisms have the potential to realize commercial production of 1- butanol from renewable resources. Future research should focus on substrate utilization, cofactor imbalance, and promoter selection to boost 1-butanol production in non-native hosts. Moreover, the application of robust genetic engineering approaches is required for metabolic engineering of microorganisms to make them industrially feasible for 1-butanol production.
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Affiliation(s)
- Said Nawab
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, People's Republic of China
| | - Ning Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, People's Republic of China.
| | - Xiaoyan Ma
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, People's Republic of China.
| | - Yi-Xin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, People's Republic of China
- Biology Institute, Shandong Province Key Laboratory for Biosensors, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250103, China
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Sechovcová H, Kulhavá L, Fliegerová K, Trundová M, Morais D, Mrázek J, Kopečný J. Comparison of enzymatic activities and proteomic profiles of Butyrivibrio fibrisolvens grown on different carbon sources. Proteome Sci 2019; 17:2. [PMID: 31168299 PMCID: PMC6545216 DOI: 10.1186/s12953-019-0150-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 05/15/2019] [Indexed: 01/12/2023] Open
Abstract
Background The rumen microbiota is one of the most complex consortia of anaerobes, involving archaea, bacteria, protozoa, fungi and phages. They are very effective at utilizing plant polysaccharides, especially cellulose and hemicelluloses. The most important hemicellulose decomposers are clustered with the genus Butyrivibrio. As the related species differ in their range of hydrolytic activities and substrate preferences, Butyrivibrio fibrisolvens was selected as one of the most effective isolates and thus suitable for proteomic studies on substrate comparisons in the extracellular fraction. The B. fibrisolvens genome is the biggest in the butyrivibria cluster and is focused on “environmental information processing” and “carbohydrate metabolism”. Methods The study of the effect of carbon source on B. fibrisolvens 3071 was based on cultures grown on four substrates: xylose, glucose, xylan, xylan with 25% glucose. The enzymatic activities were studied by spectrophotometric and zymogram methods. Proteomic study was based on genomics, 2D electrophoresis and nLC/MS (Bruker Daltonics) analysis. Results Extracellular β-endoxylanase as well as xylan β-xylosidase activities were induced with xylan. The presence of the xylan polymer induced hemicellulolytic enzymes and increased the protein fraction in the interval from 40 to 80 kDa. 2D electrophoresis with nLC/MS analysis of extracellular B. fibrisolvens 3071 proteins found 14 diverse proteins with significantly different expression on the tested substrates. Conclusion The comparison of four carbon sources resulted in the main significant changes in B. fibrisolvens proteome occurring outside the fibrolytic cluster of proteins. The affected proteins mainly belonged to the glycolysis and protein synthesis cluster. Electronic supplementary material The online version of this article (10.1186/s12953-019-0150-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hana Sechovcová
- 1Institute of Animal Physiology and Genetics, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic.,5Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 5, 166 286 Prague, Czech Republic
| | - Lucie Kulhavá
- 2Institute of Physiology, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic.,4Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 12843 Prague 2, Czech Republic
| | - Kateřina Fliegerová
- 1Institute of Animal Physiology and Genetics, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Mária Trundová
- 3Institute of Biotechnology, CAS, v.v.i., Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Daniel Morais
- 6Institute of Microbiology, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Jakub Mrázek
- 1Institute of Animal Physiology and Genetics, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Jan Kopečný
- 1Institute of Animal Physiology and Genetics, CAS, v.v.i., Vídeňská 1083, 142 20 Prague, Czech Republic
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Simultaneous Improvements of Pseudomonas Cell Growth and Polyhydroxyalkanoate Production from a Lignin Derivative for Lignin-Consolidated Bioprocessing. Appl Environ Microbiol 2018; 84:AEM.01469-18. [PMID: 30030226 DOI: 10.1128/aem.01469-18] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 07/05/2018] [Indexed: 11/20/2022] Open
Abstract
Cell growth and polyhydroxyalkanoate (PHA) biosynthesis are two key traits in PHA production from lignin or its derivatives. However, the links between them remain poorly understood. Here, the transcription levels of key genes involved in PHA biosynthesis were tracked in Pseudomonas putida strain A514 grown on vanillic acid as the sole carbon source under different levels of nutrient availability. First, enoyl-coenzyme A (CoA) hydratase (encoded by phaJ4) is stress induced and likely to contribute to PHA synthesis under nitrogen starvation conditions. Second, much higher expression levels of 3-hydroxyacyl-acyl carrier protein (ACP) thioesterase (encoded by phaG) and long-chain fatty acid-CoA ligase (encoded by alkK) under both high and low nitrogen (N) led to the hypothesis that they likely not only have a role in PHA biosynthesis but are also essential to cell growth. Third, 40 mg/liter PHA was synthesized by strain AphaJ4C1 (overexpression of phaJ4 and phaC1 in strain A514) under low-N conditions, in contrast to 23 mg/liter PHA synthesized under high-N conditions. Under high-N conditions, strain AalkKphaGC1 (overexpression of phaG, alkK, and phaC1 in A514) produced 90 mg/liter PHA with a cell dry weight of 667 mg/liter, experimentally validating our hypothesis. Finally, further enhancement in cell growth (714 mg/liter) and PHA titer (246 mg/liter) was achieved in strain Axyl_alkKphaGC1 via transcription level optimization, which was regulated by an inducible strong promoter with its regulator, XylR-PxylA, from the xylose catabolic gene cluster of the A514 genome. This study reveals genetic features of genes involved in PHA synthesis from a lignin derivative and provides a novel strategy for rational engineering of these two traits, laying the foundation for lignin-consolidated bioprocessing.IMPORTANCE With the recent advances in processing carbohydrates in lignocellulosics for bioproducts, almost all biological conversion platforms result in the formation of a significant amount of lignin by-products, representing the second most abundant feedstock on earth. However, this resource is greatly underutilized due to its heterogeneity and recalcitrant chemical structure. Thus, exploiting lignin valorization routes would achieve the complete utilization of lignocellulosic biomass and improve cost-effectiveness. The culture conditions that encourage cell growth and polyhydroxyalkanoate (PHA) accumulation are different. Such an inconsistency represents a major hurdle in lignin-to-PHA bioconversion. In this study, we traced and compared transcription levels of key genes involved in PHA biosynthesis pathways in Pseudomonas putida A514 under different nitrogen concentrations to unveil the unusual features of PHA synthesis. Furthermore, an inducible strong promoter was identified. Thus, the molecular features and new genetic tools reveal a strategy to coenhance PHA production and cell growth from a lignin derivative.
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17
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Lee BD, Apel WA, DeVeaux LC, Sheridan PP. Concurrent metabolism of pentose and hexose sugars by the polyextremophile Alicyclobacillus acidocaldarius. J Ind Microbiol Biotechnol 2017; 44:1443-1458. [PMID: 28776272 DOI: 10.1007/s10295-017-1968-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 07/18/2017] [Indexed: 11/24/2022]
Abstract
Alicyclobacillus acidocaldarius is a thermoacidophilic bacterium capable of growth on sugars from plant biomass. Carbon catabolite repression (CCR) allows bacteria to focus cellular resources on a sugar that provides efficient growth, but also allows sequential, rather than simultaneous use when more than one sugar is present. The A. acidocaldarius genome encodes all components of CCR, but transporters encoded are multifacilitator superfamily and ATP-binding cassette-type transporters, uncommon for CCR. Therefore, global transcriptome analysis of A. acidocaldarius grown on xylose or fructose was performed in chemostats, followed by attempted induction of CCR with glucose or arabinose. Alicyclobacillus acidocaldarius grew while simultaneously metabolizing xylose and glucose, xylose and arabinose, and fructose and glucose, indicating that CCR did not control carbon metabolism. Microarrays showed down-regulation of genes during growth on one sugar compared to two, and occurred primarily in genes encoding: (1) regulators; (2) enzymes for cell wall synthesis; and (3) sugar transporters.
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Affiliation(s)
- Brady D Lee
- Idaho National Laboratory, Biological Systems Department, Idaho Falls, ID, USA. .,Department of Biological Sciences, Idaho State University, Pocatello, ID, USA. .,Pacific Northwest National Laboratory, Energy and Environment Directorate, Richland, WA, USA.
| | - William A Apel
- Idaho National Laboratory, Biological Systems Department, Idaho Falls, ID, USA.,Aspenglow Associates, LLC, P. O. Box 12692, Jackson, WY, 83002, USA
| | - Linda C DeVeaux
- Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology, Rapid City, SD, USA
| | - Peter P Sheridan
- Department of Biological Sciences, Idaho State University, Pocatello, ID, USA
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18
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Yang C, Wang Q, Simon PN, Liu J, Liu L, Dai X, Zhang X, Kuang J, Igarashi Y, Pan X, Luo F. Distinct Network Interactions in Particle-Associated and Free-Living Bacterial Communities during a Microcystis aeruginosa Bloom in a Plateau Lake. Front Microbiol 2017; 8:1202. [PMID: 28713340 PMCID: PMC5492469 DOI: 10.3389/fmicb.2017.01202] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/13/2017] [Indexed: 12/23/2022] Open
Abstract
Particle-associated bacteria (PAB) and free-living bacteria (FLB) from aquatic environments during phytoplankton blooms differ in their physical distance from algae. Both the interactions within PAB and FLB community fractions and their relationship with the surrounding environmental properties are largely unknown. Here, by using high-throughput sequencing and network-based analyses, we compared the community and network characteristics of PAB and FLB from a plateau lake during a Microcystis aeruginosa bloom. Results showed that PAB and FLB differed significantly in diversity, structure and microbial connecting network. PAB communities were characterized by highly similar bacterial community structure in different sites, tighter network connections, important topological roles for the bloom-causing M. aeruginosa and Alphaproteobacteria, especially for the potentially nitrogen-fixing (Pleomorphomonas) and algicidal bacteria (Brevundimonas sp.). FLB communities were sensitive to the detected environmental factors and were characterized by significantly higher bacterial diversity, less connectivity, larger network size and marginal role of M. aeruginosa. In both networks, covariation among bacterial taxa was extensive (>88% positive connections), and bacteria potentially affiliated with biogeochemical cycling of nitrogen (i.e., denitrification, nitrogen-fixation and nitrite-oxidization) were important in occupying module hubs, such as Meganema, Pleomorphomonas, and Nitrospira. These findings highlight the importance of considering microbial network interactions for the understanding of blooms.
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Affiliation(s)
- Caiyun Yang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Qi Wang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Paulina N Simon
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Jinyu Liu
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Lincong Liu
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xianzhu Dai
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xiaohui Zhang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Jialiang Kuang
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Plant Resources and Conservation of Guangdong Higher Education Institutes, College of Ecology and Evolution, Sun Yat-sen UniversityGuangzhou, China
| | - Yasuo Igarashi
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xuejun Pan
- Faculty of Environmental Science and Engineering, Kunming University of Science and TechnologyKunming, China
| | - Feng Luo
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
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Peng T, Pan S, Christopher LP, Sparling R, Levin DB. Growth and metabolic profiling of the novel thermophilic bacterium Thermoanaerobacter sp. strain YS13. Can J Microbiol 2016; 62:762-71. [PMID: 27569998 DOI: 10.1139/cjm-2016-0040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A strictly anaerobic, thermophilic bacterium, designated strain YS13, was isolated from a geothermal hot spring. Phylogenetic analysis using the 16S rRNA genes and cpn60 UT genes suggested strain YS13 as a species of Thermoanaerobacter. Using cellobiose or xylose as carbon source, YS13 was able to grow over a wide range of temperatures (45-70 °C), and pHs (pH 5.0-9.0), with optimum growth at 65 °C and pH 7.0. Metabolic profiling on cellobiose, glucose, or xylose in 1191 medium showed that H2, CO2, ethanol, acetate, and lactate were the major metabolites. Lactate was the predominant end product from glucose or cellobiose fermentations, whereas H2 and acetate were the dominant end products from xylose fermentation. The metabolic balance shifted away from ethanol to H2, acetate, and lactate when YS13 was grown on cellobiose as temperatures increased from 45 to 70 °C. When YS13 was grown on xylose, a metabolic shift from lactate to H2, CO2, and acetate was observed in cultures as the temperature of incubation increased from 45 to 65 °C, whereas a shift from ethanol and CO2 to H2, acetate, and lactate was observed in cultures incubated at 70 °C.
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Affiliation(s)
- Tingting Peng
- a Department of Food Science, Huazhong Agricultural University, Wuhan, China.,d Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB R3T 3N3, Canada
| | - Siyi Pan
- a Department of Food Science, Huazhong Agricultural University, Wuhan, China
| | - Lew P Christopher
- b Biorefining Research Institute, Lakehead University, Thunder Bay, ON P7B 5Z5, Canada
| | - Richard Sparling
- c Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 3N3, Canada
| | - David B Levin
- d Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB R3T 3N3, Canada
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Tu Q, Zhou X, He Z, Xue K, Wu L, Reich P, Hobbie S, Zhou J. The Diversity and Co-occurrence Patterns of N₂-Fixing Communities in a CO₂-Enriched Grassland Ecosystem. MICROBIAL ECOLOGY 2016; 71:604-615. [PMID: 26280746 DOI: 10.1007/s00248-015-0659-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 08/03/2015] [Indexed: 06/04/2023]
Abstract
Diazotrophs are the major organismal group responsible for atmospheric nitrogen (N2) fixation in natural ecosystems. The extensive diversity and structure of N2-fixing communities in grassland ecosystems and their responses to increasing atmospheric CO2 remain to be further explored. Through pyrosequencing of nifH gene amplicons and extraction of nifH genes from shotgun metagenomes, coupled with co-occurrence ecological network analysis approaches, we comprehensively analyzed the diazotrophic community in a grassland ecosystem exposed to elevated CO2 (eCO2) for 12 years. Long-term eCO2 increased the abundance of nifH genes but did not change the overall nifH diversity and diazotrophic community structure. Taxonomic and phylogenetic analysis of amplified nifH sequences suggested a high diversity of nifH genes in the soil ecosystem, the majority belonging to nifH clusters I and II. Co-occurrence ecological network analysis identified different co-occurrence patterns for different groups of diazotrophs, such as Azospirillum/Actinobacteria, Mesorhizobium/Conexibacter, and Bradyrhizobium/Acidobacteria. This indicated a potential attraction of non-N2-fixers by diazotrophs in the soil ecosystem. Interestingly, more complex co-occurrence patterns were found for free-living diazotrophs than commonly known symbiotic diazotrophs, which is consistent with the physical isolation nature of symbiotic diazotrophs from the environment by root nodules. The study provides novel insights into our understanding of the microbial ecology of soil diazotrophs in natural ecosystems.
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Affiliation(s)
- Qichao Tu
- Department of Marine Sciences, Ocean College, Zhejiang University, Hangzhou, Zhejiang, 310058, China
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA
| | - Xishu Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Zhili He
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Kai Xue
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Liyou Wu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Peter Reich
- Department of Forest Resources, University of Minnesota, St. Paul, MN, 55455, USA
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, 2753, NSW, Australia
| | - Sarah Hobbie
- Department of Forest Resources, University of Minnesota, St. Paul, MN, 55455, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA.
- Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
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Zhu M, Lu Y, Wang J, Li S, Wang X. Carbon Catabolite Repression and the Related Genes of ccpA, ptsH and hprK in Thermoanaerobacterium aotearoense. PLoS One 2015; 10:e0142121. [PMID: 26540271 PMCID: PMC4634974 DOI: 10.1371/journal.pone.0142121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/16/2015] [Indexed: 01/09/2023] Open
Abstract
The strictly anaerobic, Gram-positive bacterium, Thermoanaerobacterium aotearoense SCUT27, is capable of producing ethanol, hydrogen and lactic acid by directly fermenting glucan, xylan and various lignocellulosically derived sugars. By using non-metabolizable and metabolizable sugars as substrates, we found that cellobiose, galactose, arabinose and starch utilization was strongly inhibited by the existence of 2-deoxyglucose (2-DG). However, the xylose and mannose consumptions were not markedly affected by 2-DG at the concentration of one-tenth of the metabolizable sugar. Accordingly, T. aotearoense SCUT27 could consume xylose and mannose in the presence of glucose. The carbon catabolite repression (CCR) related genes, ccpA, ptsH and hprK were confirmed to exist in T. aotearoense SCUT27 through gene cloning and protein characterization. The highly purified Histidine-containing Protein (HPr) could be specifically phosphorylated at Serine 46 by HPr kinase/phosphatase (HPrK/P) with no need to add fructose-1,6-bisphosphate (FBP) or glucose-6-phosphate (Glc-6-P) in the reaction mixture. The specific protein-interaction of catabolite control protein A (CcpA) and phosphorylated HPr was proved via affinity chromatography in the absence of formaldehyde. The equilibrium binding constant (KD) of CcpA and HPrSerP was determined as 2.22 ± 0.36 nM by surface plasmon resonance (SPR) analysis, indicating the high affinity between these two proteins.
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Affiliation(s)
- Muzi Zhu
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Yanping Lu
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Jufang Wang
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Shuang Li
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
- * E-mail:
| | - Xiaoning Wang
- State Key Laboratory of Kidney, the Institute of Life Sciences, Chinese PLA General Hospital, Beijing, China
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Teng L, Wang K, Xu J, Xu C. Flavin mononucleotide (FMN)-based fluorescent protein (FbFP) as reporter for promoter screening in Clostridium cellulolyticum. J Microbiol Methods 2015; 119:37-43. [PMID: 26427827 DOI: 10.1016/j.mimet.2015.09.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/28/2015] [Accepted: 09/28/2015] [Indexed: 12/13/2022]
Abstract
Conventional methods for screening promoters in anaerobic bacteria are generally based on detection of enzymatic reactions and thus usually complicated or strain specific. Therefore a more efficient and universal method will be valuable. Here, using cellulolytic bacteria Clostridium cellulolyticum H10 as a model, we employed an oxygen-independent flavin-based fluorescent protein (FbFP) derived from Pseudomonas putida as a quantitative reporter for the screening of promoter via monitoring fluorescence intensity. The stability and reliability of FbFP fluorescence were proven by the high correlation (R(2)=0.87) between fluorescence intensity and abundance of FbFP. Moreover, two endogenous promoters with exceptional performance were identified and characterized, including a constitutive promoter p3398 and an inducible promoter p1133. Compared to the existing reporter systems widely used in clostridia, this FbFP-based method is more rapid, intuitive and versatile, and the endogenous promoters reported here should enrich the synthetic biology toolbox for this and related organisms.
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Affiliation(s)
- Lin Teng
- Single-Cell Center, CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kun Wang
- Key Laboratory of Horticulture Science for Southern Mountainous Region, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400716, China
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
| | - Chenggang Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
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23
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Andersen RL, Jensen KM, Mikkelsen MJ. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411. PLoS One 2015; 10:e0136060. [PMID: 26295944 PMCID: PMC4546601 DOI: 10.1371/journal.pone.0136060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/30/2015] [Indexed: 11/26/2022] Open
Abstract
Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47–0.49 g/g (based on glucose, xylose, and arabinose), volumetric ethanol productivities of 1.2–2.7 g/L/h and a total sugar conversion of 90–99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion.
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Olson DG, Sparling R, Lynd LR. Ethanol production by engineered thermophiles. Curr Opin Biotechnol 2015; 33:130-41. [PMID: 25745810 DOI: 10.1016/j.copbio.2015.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 12/17/2022]
Abstract
We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from pyruvate can proceed via one of four pathways, which are named by the key pyruvate dissimilating enzyme: pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH), pyruvate formate lyase (PFL), and pyruvate ferredoxin oxidoreductase (PFOR). For each of these pathways except PFL, we see examples where ethanol production has been engineered with a yield of >90% of the theoretical maximum. In each of these cases, this engineering was achieved mainly by modulating expression of native genes. We have not found an example where a thermophilic ethanol production pathway has been transferred to a non-ethanol-producing organism to produce ethanol at high yield. A key reason for the lack of transferability of ethanol production pathways is the current lack of understanding of the enzymes involved.
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Affiliation(s)
- Daniel G Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
| | - Lee R Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States.
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Fungal communities respond to long-term CO2 elevation by community reassembly. Appl Environ Microbiol 2015; 81:2445-54. [PMID: 25616796 DOI: 10.1128/aem.04040-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Fungal communities play a major role as decomposers in the Earth's ecosystems. Their community-level responses to elevated CO2 (eCO2), one of the major global change factors impacting ecosystems, are not well understood. Using 28S rRNA gene amplicon sequencing and co-occurrence ecological network approaches, we analyzed the response of soil fungal communities in the BioCON (biodiversity, CO2, and N deposition) experimental site in Minnesota, USA, in which a grassland ecosystem has been exposed to eCO2 for 12 years. Long-term eCO2 did not significantly change the overall fungal community structure and species richness, but significantly increased community evenness and diversity. The relative abundances of 119 operational taxonomic units (OTU; ∼27% of the total captured sequences) were changed significantly. Significantly changed OTU under eCO2 were associated with decreased overall relative abundance of Ascomycota, but increased relative abundance of Basidiomycota. Co-occurrence ecological network analysis indicated that eCO2 increased fungal community network complexity, as evidenced by higher intermodular and intramodular connectivity and shorter geodesic distance. In contrast, decreased connections for dominant fungal species were observed in the eCO2 network. Community reassembly of unrelated fungal species into highly connected dense modules was observed. Such changes in the co-occurrence network topology were significantly associated with altered soil and plant properties under eCO2, especially with increased plant biomass and NH4 (+) availability. This study provided novel insights into how eCO2 shapes soil fungal communities in grassland ecosystems.
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Thermoanaerobacter thermohydrosulfuricus WC1 shows protein complement stability during fermentation of key lignocellulose-derived substrates. Appl Environ Microbiol 2013; 80:1602-15. [PMID: 24362431 DOI: 10.1128/aem.03555-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermoanaerobacter spp. have long been considered suitable Clostridium thermocellum coculture partners for improving lignocellulosic biofuel production through consolidated bioprocessing. However, studies using "omic"-based profiling to better understand carbon utilization and biofuel producing pathways have been limited to only a few strains thus far. To better characterize carbon and electron flux pathways in the recently isolated, xylanolytic strain, Thermoanaerobacter thermohydrosulfuricus WC1, label-free quantitative proteomic analyses were combined with metabolic profiling. SWATH-MS proteomic analysis quantified 832 proteins in each of six proteomes isolated from mid-exponential-phase cells grown on xylose, cellobiose, or a mixture of both. Despite encoding genes consistent with a carbon catabolite repression network observed in other Gram-positive organisms, simultaneous consumption of both substrates was observed. Lactate was the major end product of fermentation under all conditions despite the high expression of gene products involved with ethanol and/or acetate synthesis, suggesting that carbon flux in this strain may be controlled via metabolite-based (allosteric) regulation or is constrained by metabolic bottlenecks. Cross-species "omic" comparative analyses confirmed similar expression patterns for end-product-forming gene products across diverse Thermoanaerobacter spp. It also identified differences in cofactor metabolism, which potentially contribute to differences in end-product distribution patterns between the strains analyzed. The analyses presented here improve our understanding of T. thermohydrosulfuricus WC1 metabolism and identify important physiological limitations to be addressed in its development as a biotechnologically relevant strain in ethanologenic designer cocultures through consolidated bioprocessing.
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Lin L, Xu J. Dissecting and engineering metabolic and regulatory networks of thermophilic bacteria for biofuel production. Biotechnol Adv 2013; 31:827-37. [DOI: 10.1016/j.biotechadv.2013.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/06/2013] [Accepted: 03/10/2013] [Indexed: 01/08/2023]
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Lin L, Ji Y, Tu Q, Huang R, Teng L, Zeng X, Song H, Wang K, Zhou Q, Li Y, Cui Q, He Z, Zhou J, Xu J. Microevolution from shock to adaptation revealed strategies improving ethanol tolerance and production in Thermoanaerobacter. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:103. [PMID: 23875846 PMCID: PMC3751872 DOI: 10.1186/1754-6834-6-103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/17/2013] [Indexed: 05/08/2023]
Abstract
INTRODUCTION The molecular links between shock-response and adaptation remain poorly understood, particularly for extremophiles. This has hindered rational engineering of solvent tolerance and correlated traits (e.g., productivity) in extremophiles. To untangle such molecular links, here we established a model that tracked the microevolution from shock to adaptation in thermophilic bacteria. METHOD Temporal dynamics of genomes and transcriptomes was tracked for Thermoanaerobacter sp. X514 which under increasing exogenous ethanol evolved from ethanol-sensitive wild-type (Strain X) to tolerance of 2%- (XI) and eventually 6%-ethanol (XII). Based on the reconstructed transcriptional network underlying stress tolerance, genetic engineering was employed to improve ethanol tolerance and production in Thermoanaerobacter. RESULTS The spontaneous genome mutation rate (μg) of Thermoanaerobacter sp. X514, calculated at 0.045, suggested a higher mutation rate in thermophile than previously thought. Transcriptomic comparison revealed that shock-response and adaptation were distinct in nature, whereas the transcriptomes of XII resembled those of the extendedly shocked X. To respond to ethanol shock, X employed fructose-specific phosphotransferase system (PTS), Arginine Deiminase (ADI) pathway, alcohol dehydrogenase (Adh) and a distinct mechanism of V-type ATPase. As an adaptation to exogenous ethanol, XI mobilized resistance-nodulation-cell division (RND) efflux system and Adh, whereas XII, which produced higher ethanol than XI, employed ECF-type ϭ24, an alcohol catabolism operon and phase-specific heat-shock proteins (Hsps), modulated hexose/pentose-transport operon structure and reinforced membrane rigidity. Exploiting these findings, we further showed that ethanol productivity and tolerance can be improved simultaneously by overexpressing adh or ϭ24 in X. CONCLUSION Our work revealed thermophilic-bacteria specific features of adaptive evolution and demonstrated a rational strategy to engineer co-evolving industrial traits. As improvements of shock-response, stress tolerance and productivity have been crucial aims in industrial applications employing thermophiles, our findings should be valuable not just to the production of ethanol but also to a wide variety of biofuels and biochemicals.
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Affiliation(s)
- Lu Lin
- 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, P. R. China
| | - Yuetong Ji
- 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, P. R. China
| | - Qichao Tu
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - 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, P. R. 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, P. R. China
| | - Xiaowei Zeng
- 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, P. R. China
| | - Houhui Song
- 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, P. R. China
| | - Kun 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, P. R. China
| | - Qian Zhou
- 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, P. R. China
| | - Yifei Li
- 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, P. R. China
| | - Qiu Cui
- 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, P. R. China
| | - Zhili He
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 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, P. R. China
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Verbeke TJ, Zhang X, Henrissat B, Spicer V, Rydzak T, Krokhin OV, Fristensky B, Levin DB, Sparling R. Genomic evaluation of Thermoanaerobacter spp. for the construction of designer co-cultures to improve lignocellulosic biofuel production. PLoS One 2013; 8:e59362. [PMID: 23555660 PMCID: PMC3608648 DOI: 10.1371/journal.pone.0059362] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 02/13/2013] [Indexed: 02/07/2023] Open
Abstract
The microbial production of ethanol from lignocellulosic biomass is a multi-component process that involves biomass hydrolysis, carbohydrate transport and utilization, and finally, the production of ethanol. Strains of the genus Thermoanaerobacter have been studied for decades due to their innate abilities to produce comparatively high ethanol yields from hemicellulose constituent sugars. However, their inability to hydrolyze cellulose, limits their usefulness in lignocellulosic biofuel production. As such, co-culturing Thermoanaerobacter spp. with cellulolytic organisms is a plausible approach to improving lignocellulose conversion efficiencies and yields of biofuels. To evaluate native lignocellulosic ethanol production capacities relative to competing fermentative end-products, comparative genomic analysis of 11 sequenced Thermoanaerobacter strains, including a de novo genome, Thermoanaerobacter thermohydrosulfuricus WC1, was conducted. Analysis was specifically focused on the genomic potential for each strain to address all aspects of ethanol production mentioned through a consolidated bioprocessing approach. Whole genome functional annotation analysis identified three distinct clades within the genus. The genomes of Clade 1 strains encode the fewest extracellular carbohydrate active enzymes and also show the least diversity in terms of lignocellulose relevant carbohydrate utilization pathways. However, these same strains reportedly are capable of directing a higher proportion of their total carbon flux towards ethanol, rather than non-biofuel end-products, than other Thermoanaerobacter strains. Strains in Clade 2 show the greatest diversity in terms of lignocellulose hydrolysis and utilization, but proportionately produce more non-ethanol end-products than Clade 1 strains. Strains in Clade 3, in which T. thermohydrosulfuricus WC1 is included, show mid-range potential for lignocellulose hydrolysis and utilization, but also exhibit extensive divergence from both Clade 1 and Clade 2 strains in terms of cellular energetics. The potential implications regarding strain selection and suitability for industrial ethanol production through a consolidated bioprocessing co-culturing approach are examined throughout the manuscript.
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Affiliation(s)
- Tobin J. Verbeke
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xiangli Zhang
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bernard Henrissat
- Centre national de la recherche scientifique, Aix-Marseille Université, Marseille, France
| | - Vic Spicer
- Department of Physics & Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Oleg V. Krokhin
- Department of Internal Medicine & Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian Fristensky
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David B. Levin
- Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Tsakraklides V, Shaw AJ, Miller BB, Hogsett DA, Herring CD. Carbon catabolite repression in Thermoanaerobacterium saccharolyticum. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:85. [PMID: 23181505 PMCID: PMC3526391 DOI: 10.1186/1754-6834-5-85] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/25/2012] [Indexed: 02/20/2024]
Abstract
BACKGROUND The thermophilic anaerobe Thermoanaerobacterium saccharolyticum is capable of directly fermenting xylan and the biomass-derived sugars glucose, cellobiose, xylose, mannose, galactose and arabinose. It has been metabolically engineered and developed as a biocatalyst for the production of ethanol. RESULTS We report the initial characterization of the carbon catabolite repression system in this organism. We find that sugar metabolism in T. saccharolyticum is regulated by histidine-containing protein HPr. We describe a mutation in HPr, His15Asp, that leads to derepression of less-favored carbon source utilization. CONCLUSION Co-utilization of sugars can be achieved by mutation of HPr in T. saccharolyticum. Further manipulation of CCR in this organism will be instrumental in achieving complete and rapid conversion of all available sugars to ethanol.
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Affiliation(s)
| | - A Joe Shaw
- Mascoma Corporation, 67 Etna Road, Suite 300, New Hampshire, 03766, Lebanon
| | - Bethany B Miller
- Mascoma Corporation, 67 Etna Road, Suite 300, New Hampshire, 03766, Lebanon
| | - David A Hogsett
- Mascoma Corporation, 67 Etna Road, Suite 300, New Hampshire, 03766, Lebanon
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