1
|
Zaplana T, Miele S, Tolonen AC. Lachnospiraceae are emerging industrial biocatalysts and biotherapeutics. Front Bioeng Biotechnol 2024; 11:1324396. [PMID: 38239921 PMCID: PMC10794557 DOI: 10.3389/fbioe.2023.1324396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 12/05/2023] [Indexed: 01/22/2024] Open
Abstract
The Lachnospiraceae is a family of anaerobic bacteria in the class Clostridia with potential to advance the bio-economy and intestinal therapeutics. Some species of Lachnospiraceae metabolize abundant, low-cost feedstocks such as lignocellulose and carbon dioxide into value-added chemicals. Others are among the dominant species of the human colon and animal rumen, where they ferment dietary fiber to promote healthy gut and immune function. Here, we summarize recent studies of the physiology, cultivation, and genetics of Lachnospiraceae, highlighting their wide substrate utilization and metabolic products with industrial applications. We examine studies of these bacteria as Live Biotherapeutic Products (LBPs), focusing on in vivo disease models and clinical studies using them to treat infection, inflammation, metabolic syndrome, and cancer. We discuss key research areas including elucidation of intra-specific diversity and genetic modification of candidate strains that will facilitate the exploitation of Lachnospiraceae in industry and medicine.
Collapse
Affiliation(s)
| | | | - Andrew C. Tolonen
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, University of Evry, Université Paris-Saclay, Evry, France
| |
Collapse
|
2
|
Wang Z, Xu M, Li F, Bai Y, Hou J, Li X, Cao R, Deng Y, Jiang Y, Wang H, Yang W. Changes in soil bacterial communities and functional groups beneath coarse woody debris across a subalpine forest successional series. Glob Ecol Conserv 2023. [DOI: 10.1016/j.gecco.2023.e02436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
|
3
|
Rostain W, Zaplana T, Boutard M, Baum C, Tabuteau S, Sanitha M, Ramya M, Guss A, Ettwiller L, Tolonen AC. Tuning of Gene Expression in Clostridium phytofermentans Using Synthetic Promoters and CRISPRi. ACS Synth Biol 2022; 11:4077-4088. [PMID: 36427328 PMCID: PMC9765743 DOI: 10.1021/acssynbio.2c00385] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Indexed: 11/27/2022]
Abstract
Control of gene expression is fundamental to cell engineering. Here we demonstrate a set of approaches to tune gene expression in Clostridia using the model Clostridium phytofermentans. Initially, we develop a simple benchtop electroporation method that we use to identify a set of replicating plasmids and resistance markers that can be cotransformed into C. phytofermentans. We define a series of promoters spanning a >100-fold expression range by testing a promoter library driving the expression of a luminescent reporter. By insertion of tet operator sites upstream of the reporter, its expression can be quantitatively altered using the Tet repressor and anhydrotetracycline (aTc). We integrate these methods into an aTc-regulated dCas12a system with which we show in vivo CRISPRi-mediated repression of reporter and fermentation genes in C. phytofermentans. Together, these approaches advance genetic transformation and experimental control of gene expression in Clostridia.
Collapse
Affiliation(s)
- William Rostain
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| | - Tom Zaplana
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| | - Magali Boutard
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| | - Chloé Baum
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
- New
England Biolabs, Inc., 240 County Road, Ipswich, Massachusetts 01938, United States
| | - Sibylle Tabuteau
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| | - Mary Sanitha
- Molecular
Genetics Laboratory, Department of Genetic Engineering, College of
Engineering and Technology, SRM Institute
of Science and Technology, SRM Nagar, Kattankulathur-603 203, TN, India
| | - Mohandass Ramya
- Molecular
Genetics Laboratory, Department of Genetic Engineering, College of
Engineering and Technology, SRM Institute
of Science and Technology, SRM Nagar, Kattankulathur-603 203, TN, India
| | - Adam Guss
- Biosciences
Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6038, United States
| | - Laurence Ettwiller
- New
England Biolabs, Inc., 240 County Road, Ipswich, Massachusetts 01938, United States
| | - Andrew C. Tolonen
- Génomique
Métabolique, Genoscope, Institut François Jacob, CEA,
CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| |
Collapse
|
4
|
Metagenomics unveils microbial roles involved in metabolic network of flavor development in medium-temperature daqu starter. Food Res Int 2021; 140:110037. [PMID: 33648263 DOI: 10.1016/j.foodres.2020.110037] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/08/2020] [Accepted: 12/15/2020] [Indexed: 12/16/2022]
Abstract
As a widely used Asian starter culture, the quality of daqu can significantly affect the organoleptic characteristics of the final products, yet the microbial metabolic network involved in flavor development remains unclear. This study aims to investigate that network based on the dynamics of physicochemical properties, microbial community, and volatile compounds in medium-temperature daqu (MT-daqu) during spontaneous fermentation. Analyses using the metagenomic data set facilitated the gene repertoire overview of this ecosystem, indicating that Lactobacillales (mainly Weissella, Lactobacillus, and Pediococcus), Mucorales (mainly Lichtheimia), and Eurotiales (mainly Aspergillus, Rasamsonia and Byssochlamys) were the potential predominant populations successively responsible for the production of lytic enzymes and flavor precursors/compounds in MT-daqu. Flavor-relevant pathways were found to exist in multiple species, but only bacteria showed the potential to participate in butane-2,3-diol (e.g. Weissella, Lactobacillus, and Staphylococcus) and butanoate (Thermoactinomyces) metabolism, and only fungi were potentially involved in biosynthesis of guaiacol (Byssochlamys) and 4-vinylguaiacol (Aspergillus). Furthermore, a combined analysis revealed that the acidic thermal environment present in early phases was mainly due to the catabolic activities of Lactobacillales and Lichtheimia, which could contribute to the effective self-domestication of microbiota. The study helps elucidate the different metabolic roles of microorganisms and disclose the formation mechanism of daqu's partial functions, namely providing various aromatic substances/precursors and enzymes.
Collapse
|
5
|
Ma X, Thakar SB, Zhang H, Yu Z, Meng L, Yue J. Bioinformatics Analysis of The Rhizosphere Microbiota of Dangshan Su Pear in Different Soil Types. Curr Bioinform 2020. [DOI: 10.2174/1574893615666200129104523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background:
The rhizosphere microbiota are of vital importance for plant growth and
health in terrestrial ecosystems. There have been extensive studies aiming to identify the microbial
communities as well as their relationship with host plants in different soil types.
Objective:
In the present study, we have employed the high-throughput sequencing technology to
investigate the composition and structure of rhizosphere microbiota prosperous at the root of
Dangshan Su pear growing in sandy soil and clay soil.
Methods:
A high-throughput amplicon sequencing survey of the bacterial 16S rRNA genes and
fungal ITS regions from rhizosphere microbiota was firstly performed. Subsequently, several
common bacterial and fungal communities were found to be essential to Dangshan Su pear by using
a series of bioinformatics and statistics tools. Finally, the soil-preferred microbiota were identified
through variance analysis and further characterized in the genus level.
Result:
Dangshan Su pears host rich and diverse microbial communities in thin layer of soil
adhering to their roots. The composition of dominant microbial phyla is similar across different soil
types, but the quantity of each microbial community varies significantly. Specially, the relative
abundance of Firmicutes increases from 9.69% to 61.66% as the soil ecosystem changes from clay
to sandy, which can be not only conducive to the degradation of complex plant materials, but also
responsible for the disinfestation of pathogens.
Conclusion:
Our results have a symbolic significance for the potential efforts of rhizosphere
microbiota on the soil bioavailability and plant health. Through selecting soil types and altering
microbial structures, the improvement of fruit quality of Dangshan Su pear is expected to be
achieved.
Collapse
Affiliation(s)
- Xiaojing Ma
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | | | - Huimin Zhang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Zequan Yu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Li Meng
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Junyang Yue
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| |
Collapse
|
6
|
Abstract
Clostridia are a group of Gram-positive anaerobic bacteria of medical and industrial importance for which limited genetic methods are available. Here, we demonstrate an approach to make large genomic deletions and insertions in the model Clostridium phytofermentans by combining designed group II introns (targetrons) and Cre recombinase. We apply these methods to delete a 50-gene prophage island by programming targetrons to position markerless lox66 and lox71 sites, which mediate deletion of the intervening 39-kb DNA region using Cre recombinase. Gene expression and growth of the deletion strain showed that the prophage genes contribute to fitness on nonpreferred carbon sources. We also inserted an inducible fluorescent reporter gene into a neutral genomic site by recombination-mediated cassette exchange (RMCE) between genomic and plasmid-based tandem lox sites bearing heterospecific spacers to prevent intracassette recombination. These approaches generally enable facile markerless genome engineering in clostridia to study their genome structure and regulation.IMPORTANCE Clostridia are anaerobic bacteria with important roles in intestinal and soil microbiomes. The inability to experimentally modify the genomes of clostridia has limited their study and application in biotechnology. Here, we developed a targetron-recombinase system to efficiently make large targeted genomic deletions and insertions using the model Clostridium phytofermentans We applied this approach to reveal the importance of a prophage to host fitness and introduce an inducible reporter by recombination-mediated cassette exchange.
Collapse
|
7
|
López-Mondéjar R, Algora C, Baldrian P. Lignocellulolytic systems of soil bacteria: A vast and diverse toolbox for biotechnological conversion processes. Biotechnol Adv 2019; 37:107374. [DOI: 10.1016/j.biotechadv.2019.03.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/06/2019] [Accepted: 03/21/2019] [Indexed: 12/12/2022]
|
8
|
ABC Transporters Required for Hexose Uptake by Clostridium phytofermentans. J Bacteriol 2019; 201:JB.00241-19. [PMID: 31109990 DOI: 10.1128/jb.00241-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 05/13/2019] [Indexed: 01/02/2023] Open
Abstract
The mechanisms by which bacteria uptake solutes across the cell membrane broadly impact their cellular energetics. Here, we use functional genomic, genetic, and biophysical approaches to reveal how Clostridium (Lachnoclostridium) phytofermentans, a model bacterium that ferments lignocellulosic biomass, uptakes plant hexoses using highly specific, nonredundant ATP-binding cassette (ABC) transporters. We analyze the transcription patterns of its 173 annotated sugar transporter genes to find those upregulated on specific carbon sources. Inactivation of these genes reveals that individual ABC transporters are required for uptake of hexoses and hexo-oligosaccharides and that distinct ABC transporters are used for oligosaccharides versus their constituent monomers. The thermodynamics of sugar binding shows that substrate specificity of these transporters is encoded by the extracellular solute-binding subunit. As sugars are not phosphorylated during ABC transport, we identify intracellular hexokinases based on in vitro activities. These mechanisms used by Clostridia to uptake plant hexoses are key to understanding soil and intestinal microbiomes and to engineer strains for industrial transformation of lignocellulose.IMPORTANCE Plant-fermenting Clostridia are anaerobic bacteria that recycle plant matter in soil and promote human health by fermenting dietary fiber in the intestine. Clostridia degrade plant biomass using extracellular enzymes and then uptake the liberated sugars for fermentation. The main sugars in plant biomass are hexoses, and here, we identify how hexoses are taken in to the cell by the model organism Clostridium phytofermentans We show that this bacterium uptakes hexoses using a set of highly specific, nonredundant ABC transporters. Once in the cell, the hexoses are phosphorylated by intracellular hexokinases. This study provides insight into the functioning of abundant members of soil and intestinal microbiomes and identifies gene targets to engineer strains for industrial lignocellulosic fermentation.
Collapse
|
9
|
Deveau A, Bonito G, Uehling J, Paoletti M, Becker M, Bindschedler S, Hacquard S, Hervé V, Labbé J, Lastovetsky OA, Mieszkin S, Millet LJ, Vajna B, Junier P, Bonfante P, Krom BP, Olsson S, van Elsas JD, Wick LY. Bacterial-fungal interactions: ecology, mechanisms and challenges. FEMS Microbiol Rev 2018; 42:335-352. [PMID: 29471481 DOI: 10.1093/femsre/fuy008] [Citation(s) in RCA: 329] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 02/16/2018] [Indexed: 12/14/2022] Open
Abstract
Fungi and bacteria are found living together in a wide variety of environments. Their interactions are significant drivers of many ecosystem functions and are important for the health of plants and animals. A large number of fungal and bacterial families engage in complex interactions that lead to critical behavioural shifts of the microorganisms ranging from mutualism to antagonism. The importance of bacterial-fungal interactions (BFI) in environmental science, medicine and biotechnology has led to the emergence of a dynamic and multidisciplinary research field that combines highly diverse approaches including molecular biology, genomics, geochemistry, chemical and microbial ecology, biophysics and ecological modelling. In this review, we discuss recent advances that underscore the roles of BFI across relevant habitats and ecosystems. A particular focus is placed on the understanding of BFI within complex microbial communities and in regard of the metaorganism concept. We also discuss recent discoveries that clarify the (molecular) mechanisms involved in bacterial-fungal relationships, and the contribution of new technologies to decipher generic principles of BFI in terms of physical associations and molecular dialogues. Finally, we discuss future directions for research in order to stimulate synergy within the BFI research area and to resolve outstanding questions.
Collapse
Affiliation(s)
- Aurélie Deveau
- Université de Lorraine, INRA, UMR IAM, 54280 Champenoux, France
| | - Gregory Bonito
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - Jessie Uehling
- Biology Department, Duke University, Box 90338, Durham, NC 27705, USA.,Plant and Microbial Biology, University of California, Berkeley, CA 94703, USA
| | - Mathieu Paoletti
- Institut de Biologie et Génétique Cellulaire, UMR 5095 CNRS et Université de Bordeaux, 1 rue Camille Saint-Saëns, 33077 Bordeaux cedex, France
| | - Matthias Becker
- IGZ, Leibniz-Institute of Vegetable and Ornamental Crops, 14979 Großbeeren, Germany
| | - Saskia Bindschedler
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
| | - Stéphane Hacquard
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Vincent Hervé
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland.,Laboratory of Biogeosciences, Institute of Earth Surface Dynamics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Jessy Labbé
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Olga A Lastovetsky
- Graduate Field of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Sophie Mieszkin
- Université de Lorraine, INRA, UMR IAM, 54280 Champenoux, France
| | - Larry J Millet
- Joint Institute for Biological Science, University of Tennessee, and the Biosciences Division of Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Balázs Vajna
- Department of Microbiology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary
| | - Pilar Junier
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
| | - Paola Bonfante
- Department of Life Science and Systems Biology, University of Torino, 10125 Torino, Italy
| | - Bastiaan P Krom
- Department of Preventive Dentistry, Academic Centre for Dentistry, G. Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Stefan Olsson
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China
| | - Jan Dirk van Elsas
- Microbial Ecology group, GELIFES, University of Groningen, 9747 Groningen, The Netherlands
| | - Lukas Y Wick
- Helmholtz Centre for Environmental Research-UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany
| |
Collapse
|
10
|
Steven J. VD, Richard M. L. Chitins and chitinase activity in airway diseases. J Allergy Clin Immunol 2018; 142:364-369. [PMID: 29959948 PMCID: PMC6078791 DOI: 10.1016/j.jaci.2018.06.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 06/19/2018] [Accepted: 06/22/2018] [Indexed: 01/04/2023]
Abstract
Chitin, one of the most abundant biopolymers on Earth, is bound and degraded by chitinases, specialized enzymes that are similarly widespread in nature. Chitin catabolism affects global carbon and nitrogen cycles through a host of diverse biological processes, but recent work has focused attention on systems of chitin recognition and degradation conserved in mammals, connecting an ancient pathway of polysaccharide processing to human diseases influenced by persistent immune triggering. Here we review current advances in our understanding of how chitin-chitinase interactions affect mucosal immune feedback mechanisms essential to maintaining homeostasis and organ health.
Collapse
Affiliation(s)
- Van Dyken Steven J.
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO USA.
| | - Locksley Richard M.
- Howard Hughes Medical Institute, Departments of Medicine and Microbiology / Immuology, University of California San Francisco, San Francisco, CA, USA.
| |
Collapse
|
11
|
Evolution of a Biomass-Fermenting Bacterium To Resist Lignin Phenolics. Appl Environ Microbiol 2017; 83:AEM.00289-17. [PMID: 28363966 DOI: 10.1128/aem.00289-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/24/2017] [Indexed: 02/05/2023] Open
Abstract
Increasing the resistance of plant-fermenting bacteria to lignocellulosic inhibitors is useful to understand microbial adaptation and to develop candidate strains for consolidated bioprocessing. Here, we study and improve inhibitor resistance in Clostridium phytofermentans (also called Lachnoclostridium phytofermentans), a model anaerobe that ferments lignocellulosic biomass. We survey the resistance of this bacterium to a panel of biomass inhibitors and then evolve strains that grow in increasing concentrations of the lignin phenolic, ferulic acid, by automated, long-term growth selection in an anaerobic GM3 automat. Ultimately, strains resist multiple inhibitors and grow robustly at the solubility limit of ferulate while retaining the ability to ferment cellulose. We analyze genome-wide transcription patterns during ferulate stress and genomic variants that arose along the ferulate growth selection, revealing how cells adapt to inhibitors through changes in gene dosage and regulation, membrane fatty acid structure, and the surface layer. Collectively, this study demonstrates an automated framework for in vivo directed evolution of anaerobes and gives insight into the genetic mechanisms by which bacteria survive exposure to chemical inhibitors.IMPORTANCE Fermentation of plant biomass is a key part of carbon cycling in diverse ecosystems. Further, industrial biomass fermentation may provide a renewable alternative to fossil fuels. Plants are primarily composed of lignocellulose, a matrix of polysaccharides and polyphenolic lignin. Thus, when microorganisms degrade lignocellulose to access sugars, they also release phenolic and acidic inhibitors. Here, we study how the plant-fermenting bacterium Clostridium phytofermentans resists plant inhibitors using the lignin phenolic, ferulic acid. We examine how the cell responds to abrupt ferulate stress by measuring changes in gene expression. We evolve increasingly resistant strains by automated, long-term cultivation at progressively higher ferulate concentrations and sequence their genomes to identify mutations associated with acquired ferulate resistance. Our study develops an inhibitor-resistant bacterium that ferments cellulose and provides insights into genomic evolution to resist chemical inhibitors.
Collapse
|
12
|
Forest Soil Bacteria: Diversity, Involvement in Ecosystem Processes, and Response to Global Change. Microbiol Mol Biol Rev 2017; 81:81/2/e00063-16. [PMID: 28404790 DOI: 10.1128/mmbr.00063-16] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ecology of forest soils is an important field of research due to the role of forests as carbon sinks. Consequently, a significant amount of information has been accumulated concerning their ecology, especially for temperate and boreal forests. Although most studies have focused on fungi, forest soil bacteria also play important roles in this environment. In forest soils, bacteria inhabit multiple habitats with specific properties, including bulk soil, rhizosphere, litter, and deadwood habitats, where their communities are shaped by nutrient availability and biotic interactions. Bacteria contribute to a range of essential soil processes involved in the cycling of carbon, nitrogen, and phosphorus. They take part in the decomposition of dead plant biomass and are highly important for the decomposition of dead fungal mycelia. In rhizospheres of forest trees, bacteria interact with plant roots and mycorrhizal fungi as commensalists or mycorrhiza helpers. Bacteria also mediate multiple critical steps in the nitrogen cycle, including N fixation. Bacterial communities in forest soils respond to the effects of global change, such as climate warming, increased levels of carbon dioxide, or anthropogenic nitrogen deposition. This response, however, often reflects the specificities of each studied forest ecosystem, and it is still impossible to fully incorporate bacteria into predictive models. The understanding of bacterial ecology in forest soils has advanced dramatically in recent years, but it is still incomplete. The exact extent of the contribution of bacteria to forest ecosystem processes will be recognized only in the future, when the activities of all soil community members are studied simultaneously.
Collapse
|
13
|
Boutard M, Ettwiller L, Cerisy T, Alberti A, Labadie K, Salanoubat M, Schildkraut I, Tolonen AC. Global repositioning of transcription start sites in a plant-fermenting bacterium. Nat Commun 2016; 7:13783. [PMID: 27982035 PMCID: PMC5171806 DOI: 10.1038/ncomms13783] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/01/2016] [Indexed: 01/03/2023] Open
Abstract
Bacteria respond to their environment by regulating mRNA synthesis, often by altering the genomic sites at which RNA polymerase initiates transcription. Here, we investigate genome-wide changes in transcription start site (TSS) usage by Clostridium phytofermentans, a model bacterium for fermentation of lignocellulosic biomass. We quantify expression of nearly 10,000 TSS at single base resolution by Capp-Switch sequencing, which combines capture of synthetically capped 5' mRNA fragments with template-switching reverse transcription. We find the locations and expression levels of TSS for hundreds of genes change during metabolism of different plant substrates. We show that TSS reveals riboswitches, non-coding RNA and novel transcription units. We identify sequence motifs associated with carbon source-specific TSS and use them for regulon discovery, implicating a LacI/GalR protein in control of pectin metabolism. We discuss how the high resolution and specificity of Capp-Switch enables study of condition-specific changes in transcription initiation in bacteria.
Collapse
Affiliation(s)
- Magali Boutard
- 1CEA, DRF, IG, Genoscope, Évry 91000, France.,CNRS-UMR8030, Évry 91000, France
| | | | - Tristan Cerisy
- 1CEA, DRF, IG, Genoscope, Évry 91000, France.,CNRS-UMR8030, Évry 91000, France.,Université Paris-Saclay, Évry 91000, France.,Université d'Évry, Évry 91000, France
| | | | | | - Marcel Salanoubat
- 1CEA, DRF, IG, Genoscope, Évry 91000, France.,CNRS-UMR8030, Évry 91000, France.,Université Paris-Saclay, Évry 91000, France.,Université d'Évry, Évry 91000, France
| | - Ira Schildkraut
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Andrew C Tolonen
- 1CEA, DRF, IG, Genoscope, Évry 91000, France.,CNRS-UMR8030, Évry 91000, France.,Université Paris-Saclay, Évry 91000, France.,Université d'Évry, Évry 91000, France
| |
Collapse
|
14
|
Johnston SR, Boddy L, Weightman AJ. Bacteria in decomposing wood and their interactions with wood-decay fungi. FEMS Microbiol Ecol 2016; 92:fiw179. [PMID: 27559028 DOI: 10.1093/femsec/fiw179] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2016] [Indexed: 01/02/2023] Open
Abstract
The fungal community within dead wood has received considerable study, but far less attention has been paid to bacteria in the same habitat. Bacteria have long been known to inhabit decomposing wood, but much remains underexplored about their identity and ecology. Bacteria within the dead wood environment must interact with wood-decay fungi, but again, very little is known about the form this takes; there are indications of both antagonistic and beneficial interactions within this fungal microbiome. Fungi are hypothesised to play an important role in shaping bacterial communities in wood, and conversely, bacteria may affect wood-decay fungi in a variety of ways. This minireview considers what is currently known about bacteria in wood and their interactions with fungi, and proposes possible associations based on examples from other habitats. It aims to identify key knowledge gaps and pressing questions for future research.
Collapse
Affiliation(s)
- Sarah R Johnston
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Lynne Boddy
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Andrew J Weightman
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, UK
| |
Collapse
|
15
|
Physiology, Genomics, and Pathway Engineering of an Ethanol-Tolerant Strain of Clostridium phytofermentans. Appl Environ Microbiol 2015; 81:5440-8. [PMID: 26048945 DOI: 10.1128/aem.00619-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/27/2015] [Indexed: 01/21/2023] Open
Abstract
Novel processing strategies for hydrolysis and fermentation of lignocellulosic biomass in a single reactor offer large potential cost savings for production of biocommodities and biofuels. One critical challenge is retaining high enzyme production in the presence of elevated product titers. Toward this goal, the cellulolytic, ethanol-producing bacterium Clostridium phytofermentans was adapted to increased ethanol concentrations. The resulting ethanol-tolerant (ET) strain has nearly doubled ethanol tolerance relative to the wild-type level but also reduced ethanol yield and growth at low ethanol concentrations. The genome of the ET strain has coding changes in proteins involved in membrane biosynthesis, the Rnf complex, cation homeostasis, gene regulation, and ethanol production. In particular, purification of the mutant bifunctional acetaldehyde coenzyme A (CoA)/alcohol dehydrogenase showed that a G609D variant abolished its activities, including ethanol formation. Heterologous expression of Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase in the ET strain increased cellulose consumption and restored ethanol production, demonstrating how metabolic engineering can be used to overcome disadvantageous mutations incurred during adaptation to ethanol. We discuss how genetic changes in the ET strain reveal novel potential strategies for improving microbial solvent tolerance.
Collapse
|
16
|
Wegner CE, Liesack W. Microbial community dynamics during the early stages of plant polymer breakdown in paddy soil. Environ Microbiol 2015; 18:2825-42. [PMID: 25712035 DOI: 10.1111/1462-2920.12815] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 02/04/2015] [Accepted: 02/11/2015] [Indexed: 12/01/2022]
Abstract
We used paddy soil slurries amended with rice straw to identify the microbial populations involved in the methanogenic breakdown of plant polymers. Rice straw greatly stimulated microbial activity over the 28-day incubation period. On day 7, the transient peak concentration of acetate (24 mM) coincided with the onset of increased methane production. Microbial 16S rRNA transcript numbers increased by one to two orders of magnitude, but not the 16S rRNA gene copy numbers. Using metatranscriptomic rRNA, Clostridiaceae, Lachnospiraceae, Ruminococcaceae, Veillonellaceae and Pseudomonadaceae were identified to be the most abundant and the most dynamic bacterial groups. Changes in methanogen rRNA and mRNA abundances corresponded well with methanogenic activity. Acetate determined the abundance ratio between Methanosarcinaceae and Methanosaetaceae. Methanocellaceae dominated hydrogenotrophic methanogenesis. Transcript levels of mRNA families involved in plant polymer breakdown increased slightly with time. Glycosyl hydrolase (GH) transcripts involved in cellulose and chitin breakdown were predominantly expressed by the Firmicutes, whereas those involved in hemicellulose breakdown exhibited more diverse taxonomic sources, including Acidobacteria, Bacteriodetes and Chloroflexi. Taken together, we observed strong population dynamics and the expression of taxonomically diverse GH families, suggesting that not only Firmicutes, but also less abundant groups play a major functional role in the decomposition of rice straw.
Collapse
Affiliation(s)
- Carl-Eric Wegner
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043, Marburg (Lahn), Germany
| | - Werner Liesack
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043, Marburg (Lahn), Germany.
| |
Collapse
|
17
|
Boutard M, Cerisy T, Nogue PY, Alberti A, Weissenbach J, Salanoubat M, Tolonen AC. Functional diversity of carbohydrate-active enzymes enabling a bacterium to ferment plant biomass. PLoS Genet 2014; 10:e1004773. [PMID: 25393313 PMCID: PMC4230839 DOI: 10.1371/journal.pgen.1004773] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/24/2014] [Indexed: 12/16/2022] Open
Abstract
Microbial metabolism of plant polysaccharides is an important part of environmental carbon cycling, human nutrition, and industrial processes based on cellulosic bioconversion. Here we demonstrate a broadly applicable method to analyze how microbes catabolize plant polysaccharides that integrates carbohydrate-active enzyme (CAZyme) assays, RNA sequencing (RNA-seq), and anaerobic growth screening. We apply this method to study how the bacterium Clostridium phytofermentans ferments plant biomass components including glucans, mannans, xylans, galactans, pectins, and arabinans. These polysaccharides are fermented with variable efficiencies, and diauxies prioritize metabolism of preferred substrates. Strand-specific RNA-seq reveals how this bacterium responds to polysaccharides by up-regulating specific groups of CAZymes, transporters, and enzymes to metabolize the constituent sugars. Fifty-six up-regulated CAZymes were purified, and their activities show most polysaccharides are degraded by multiple enzymes, often from the same family, but with divergent rates, specificities, and cellular localizations. CAZymes were then tested in combination to identify synergies between enzymes acting on the same substrate with different catalytic mechanisms. We discuss how these results advance our understanding of how microbes degrade and metabolize plant biomass.
Collapse
Affiliation(s)
- Magali Boutard
- Genoscope, CEA, DSV, IG, Évry, France
- CNRS-UMR8030, Évry, France
- Department of Biology, Université d'Évry Val d'Essonne, Évry, France
| | - Tristan Cerisy
- Genoscope, CEA, DSV, IG, Évry, France
- CNRS-UMR8030, Évry, France
- Department of Biology, Université d'Évry Val d'Essonne, Évry, France
| | - Pierre-Yves Nogue
- Genoscope, CEA, DSV, IG, Évry, France
- CNRS-UMR8030, Évry, France
- Department of Biology, Université d'Évry Val d'Essonne, Évry, France
| | | | | | - Marcel Salanoubat
- Genoscope, CEA, DSV, IG, Évry, France
- CNRS-UMR8030, Évry, France
- Department of Biology, Université d'Évry Val d'Essonne, Évry, France
| | - Andrew C. Tolonen
- Genoscope, CEA, DSV, IG, Évry, France
- CNRS-UMR8030, Évry, France
- Department of Biology, Université d'Évry Val d'Essonne, Évry, France
- * E-mail:
| |
Collapse
|