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Hink L, Holzinger A, Sandfeld T, Weig AR, Schramm A, Feldhaar H, Horn MA. Microplastic ingestion affects hydrogen production and microbiomes in the gut of the terrestrial isopod Porcellio scaber. Environ Microbiol 2023; 25:2776-2791. [PMID: 37041018 DOI: 10.1111/1462-2920.16386] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 03/31/2023] [Indexed: 04/13/2023]
Abstract
Microplastic (MP) is an environmental burden and enters food webs via ingestion by macrofauna, including isopods (Porcellio scaber) in terrestrial ecosystems. Isopods represent ubiquitously abundant, ecologically important detritivores. However, MP-polymer specific effects on the host and its gut microbiota are unknown. We tested the hypothesis that biodegradable (polylactic acid [PLA]) and non-biodegradable (polyethylene terephthalate [PET]; polystyrene [PS]) MPs have contrasting effects on P. scaber mediated by changes of the gut microbiota. The isopod fitness after an 8-week MP-exposure was generally unaffected, although the isopods showed avoidance behaviour to PS-food. MP-polymer specific effects on gut microbes were detected, including a stimulation of microbial activity by PLA compared with MP-free controls. PLA stimulated hydrogen emission from isopod guts, while PET and PS were inhibitory. We roughly estimated 107 kg year-1 hydrogen emitted from the isopods globally and identified their guts as anoxic, significant mobile sources of reductant for soil microbes despite the absence of classical obligate anaerobes, likely due to Enterobacteriaceae-related fermentation activities that were stimulated by lactate generated during PLA-degradation. The findings suggest negative effects of PET and PS on gut fermentation, modulation of important isopod hydrogen emissions by MP pollution and the potential of MP to affect terrestrial food webs.
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Affiliation(s)
- Linda Hink
- Institute of Microbiology, Leibniz University Hannover, Hannover, Germany
| | - Anja Holzinger
- Animal Population Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Tobias Sandfeld
- Department of Biology, Section for Microbiology, Aarhus University, Aarhus, Denmark
| | - Alfons R Weig
- Genomics and Bioinformatics, University of Bayreuth, Bayreuth, Germany
| | - Andreas Schramm
- Department of Biology, Section for Microbiology, Aarhus University, Aarhus, Denmark
| | - Heike Feldhaar
- Animal Population Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Marcus A Horn
- Institute of Microbiology, Leibniz University Hannover, Hannover, Germany
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2
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Morgavi DP, Cantalapiedra-Hijar G, Eugène M, Martin C, Noziere P, Popova M, Ortigues-Marty I, Muñoz-Tamayo R, Ungerfeld EM. Review: Reducing enteric methane emissions improves energy metabolism in livestock: is the tenet right? Animal 2023; 17 Suppl 3:100830. [PMID: 37263815 DOI: 10.1016/j.animal.2023.100830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/21/2022] [Accepted: 12/30/2022] [Indexed: 06/03/2023] Open
Abstract
The production of enteric methane in the gastrointestinal tract of livestock is considered as an energy loss in the equations for estimating energy metabolism in feeding systems. Therefore, the spared energy resulting from specific inhibition of methane emissions should be re-equilibrated with other factors of the equation. And, it is commonly assumed that net energy from feeds increases, thus benefitting production functions, particularly in ruminants due to the important production of methane in the rumen. Notwithstanding, we confirm in this work that inhibition of emissions in ruminants does not transpose into consistent improvements in production. Theoretical calculations of energy flows using experimental data show that the expected improvement in net energy for production is small and difficult to detect under the prevailing, moderate inhibition of methane production (≈25%) obtained using feed additives inhibiting methanogenesis. Importantly, the calculation of energy partitioning using canonical models might not be adequate when methanogenesis is inhibited. There is a lack of information on various parameters that play a role in energy partitioning and that may be affected under provoked abatement of methane. The formula used to calculate heat production based on respiratory exchanges should be validated when methanogenesis is inhibited. Also, a better understanding is needed of the effects of inhibition on fermentation products, fermentation heat, and microbial biomass. Inhibition induces the accumulation of H2, the main substrate used to produce methane, that has no energetic value for the host, and it is not extensively used by the majority of rumen microbes. Currently, the fate of this excess of H2 and its consequences on the microbiota and the host are not well known. All this additional information will provide a better account of energy transactions in ruminants when enteric methanogenesis is inhibited. Based on the available information, it is concluded that the claim that enteric methane inhibition will translate into more feed-efficient animals is not warranted.
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Affiliation(s)
- D P Morgavi
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France.
| | - G Cantalapiedra-Hijar
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - M Eugène
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - C Martin
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - P Noziere
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - M Popova
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - I Ortigues-Marty
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genes-Champanelle, France
| | - R Muñoz-Tamayo
- Université Paris-Saclay, INRAE, AgroParisTech, UMR Modélisation Systémique Appliquée aux Ruminants, 91120 Palaiseau, France
| | - E M Ungerfeld
- Centro Regional de Investigación Carillanca, Instituto de Investigaciones Agropecuarias INIA, Temuco 4880000, Chile
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Comparative Analysis of Brucepastera parasyntrophica gen. nov., sp. nov. and Teretinema zuelzerae gen. nov., comb. nov. ( Treponemataceae) Reveals the Importance of Interspecies Hydrogen Transfer in the Energy Metabolism of Spirochetes. Appl Environ Microbiol 2022; 88:e0050322. [PMID: 35862663 PMCID: PMC9317865 DOI: 10.1128/aem.00503-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Most members of the family Treponemataceae (Spirochaetales) are associated with vertebrate hosts. However, a diverse clade of uncultured, putatively free-living treponemes comprising several genus-level lineages is present in other anoxic environments. The only cultivated representative to date is Treponema zuelzerae, isolated from freshwater mud. Here, we describe the isolation of strain RmG11 from the intestinal tract of cockroaches. The strain represents a novel genus-level lineage of Treponemataceae and is metabolically distinct from T. zuelzerae. While T. zuelzerae grows well on various sugars, forming acetate and H2 as major fermentation products, strain RmG11 grew poorly on glucose, maltose, and starch, forming mainly ethanol and only small amounts of acetate and H2. In contrast to the growth of T. zuelzerae, that of strain RmG11 was strongly inhibited at high H2 partial pressures but improved considerably when H2 was removed from the headspace. Cocultures of strain RmG11 with the H2-consuming Methanospirillum hungatei produced acetate and methane but no ethanol. Comparative genomic analysis revealed that strain RmG11 possesses only a single, electron-confurcating hydrogenase that forms H2 from NADH and reduced ferredoxin, whereas T. zuelzerae also possesses a second, ferredoxin-dependent hydrogenase that allows the thermodynamically more favorable formation of H2 from ferredoxin via the Rnf complex. In addition, we found that T. zuelzerae utilizes xylan and possesses the genomic potential to degrade other plant polysaccharides. Based on phenotypic and phylogenomic evidence, we describe strain RmG11 as Brucepastera parasyntrophica gen. nov., sp. nov. and Treponema zuelzerae as Teretinema zuelzerae gen. nov., comb. nov. IMPORTANCE Spirochetes are widely distributed in various anoxic environments and commonly form molecular hydrogen as a major fermentation product. Here, we show that two closely related members of the family Treponemataceae differ strongly in their sensitivity to high hydrogen partial pressure, and we explain the metabolic mechanisms that cause these differences by comparative genome analysis. We demonstrate a strong boost in the growth of the hydrogen-sensitive strain and a shift in its fermentation products to acetate during cocultivation with a H2-utilizing methanogen. Our results add a hitherto unrecognized facet to the fermentative metabolism of spirochetes and also underscore the importance of interspecies hydrogen transfer in not-obligately-syntrophic interactions among fermentative and hydrogenotrophic guilds in anoxic environments.
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Franco Cairo JPL, Mandelli F, Tramontina R, Cannella D, Paradisi A, Ciano L, Ferreira MR, Liberato MV, Brenelli LB, Gonçalves TA, Rodrigues GN, Alvarez TM, Mofatto LS, Carazzolle MF, Pradella JGC, Paes Leme AF, Costa-Leonardo AM, Oliveira-Neto M, Damasio A, Davies GJ, Felby C, Walton PH, Squina FM. Oxidative cleavage of polysaccharides by a termite-derived superoxide dismutase boosts the degradation of biomass by glycoside hydrolases. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2022; 24:4845-4858. [PMID: 35813357 PMCID: PMC9208272 DOI: 10.1039/d1gc04519a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/07/2022] [Indexed: 05/31/2023]
Abstract
Wood-feeding termites effectively degrade plant biomass through enzymatic degradation. Despite their high efficiencies, however, individual glycoside hydrolases isolated from termites and their symbionts exhibit anomalously low effectiveness in lignocellulose degradation, suggesting hereto unknown enzymatic activities in their digestome. Herein, we demonstrate that an ancient redox-active enzyme encoded by the lower termite Coptotermes gestroi, a Cu/Zn superoxide dismutase (CgSOD-1), plays a previously unknown role in plant biomass degradation. We show that CgSOD-1 transcripts and peptides are up-regulated in response to an increased level of lignocellulose recalcitrance and that CgSOD-1 localizes in the lumen of the fore- and midguts of C. gestroi together with termite main cellulase, CgEG-1-GH9. CgSOD-1 boosts the saccharification of polysaccharides by CgEG-1-GH9. We show that the boosting effect of CgSOD-1 involves an oxidative mechanism of action in which CgSOD-1 generates reactive oxygen species that subsequently cleave the polysaccharide. SOD-type enzymes constitute a new addition to the growing family of oxidases, ones which are up-regulated when exposed to recalcitrant polysaccharides, and that are used by Nature for biomass degradation.
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Affiliation(s)
- João Paulo L Franco Cairo
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP) Campinas São Paulo Brazil
- Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen Rolighedsvej 23 DK-1958 Frederiksberg C Denmark
- Department of Chemistry, University of York York YO10 5DD UK
| | - Fernanda Mandelli
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials Campinas São Paulo Brazil
| | - Robson Tramontina
- Programa de Processos Tecnológicos e Ambientais da Universidade de Sorocaba (UNISO) Sorocaba SP Brazil
| | - David Cannella
- Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen Rolighedsvej 23 DK-1958 Frederiksberg C Denmark
| | | | - Luisa Ciano
- Department of Chemistry, University of York York YO10 5DD UK
| | - Marcel R Ferreira
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP Botucatu São Paulo Brasil
| | - Marcelo V Liberato
- Programa de Processos Tecnológicos e Ambientais da Universidade de Sorocaba (UNISO) Sorocaba SP Brazil
| | - Lívia B Brenelli
- Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen Rolighedsvej 23 DK-1958 Frederiksberg C Denmark
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials Campinas São Paulo Brazil
| | - Thiago A Gonçalves
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP) Campinas São Paulo Brazil
| | - Gisele N Rodrigues
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials Campinas São Paulo Brazil
| | - Thabata M Alvarez
- Programa de Mestrado e Doutorado em Biotecnologia Industrial, Universidade Positivo Curitiba PR Brasil
| | - Luciana S Mofatto
- Laboratório de Genômica e Expressão, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade de Campinas, UNICAMP Campinas São Paulo Brasil
| | - Marcelo F Carazzolle
- Laboratório de Genômica e Expressão, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade de Campinas, UNICAMP Campinas São Paulo Brasil
| | - José G C Pradella
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials Campinas São Paulo Brazil
| | - Adriana F Paes Leme
- Laboratório Nacional de Biociências (LNBio) do Centro Nacional de Pesquisa em Energia e Materiais (CNPEM) Campinas São Paulo Brasil
| | - Ana M Costa-Leonardo
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista, UNESP Rio Claro São Paulo Brasil
| | - Mário Oliveira-Neto
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP Botucatu São Paulo Brasil
| | - André Damasio
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP) Campinas São Paulo Brazil
| | - Gideon J Davies
- Department of Chemistry, University of York York YO10 5DD UK
| | - Claus Felby
- Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen Rolighedsvej 23 DK-1958 Frederiksberg C Denmark
| | - Paul H Walton
- Department of Chemistry, University of York York YO10 5DD UK
| | - Fabio M Squina
- Programa de Processos Tecnológicos e Ambientais da Universidade de Sorocaba (UNISO) Sorocaba SP Brazil
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Karekar S, Stefanini R, Ahring B. Homo-Acetogens: Their Metabolism and Competitive Relationship with Hydrogenotrophic Methanogens. Microorganisms 2022; 10:microorganisms10020397. [PMID: 35208852 PMCID: PMC8875654 DOI: 10.3390/microorganisms10020397] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/01/2022] [Accepted: 02/02/2022] [Indexed: 12/04/2022] Open
Abstract
Homo-acetogens are microbes that have the ability to grow on gaseous substrates such as H2/CO2/CO and produce acetic acid as the main product of their metabolism through a metabolic process called reductive acetogenesis. These acetogens are dispersed in nature and are found to grow in various biotopes on land, water and sediments. They are also commonly found in the gastro-intestinal track of herbivores that rely on a symbiotic relationship with microbes in order to breakdown lignocellulosic biomass to provide the animal with nutrients and energy. For this motive, the fermentation scheme that occurs in the rumen has been described equivalent to a consolidated bioprocessing fermentation for the production of bioproducts derived from livestock. This paper reviews current knowledge of homo-acetogenesis and its potential to improve efficiency in the rumen for production of bioproducts by replacing methanogens, the principal H2-scavengers in the rumen, thus serving as a form of carbon sink by deviating the formation of methane into bioproducts. In this review, we discuss the main strategies employed by the livestock industry to achieve methanogenesis inhibition, and also explore homo-acetogenic microorganisms and evaluate the members for potential traits and characteristics that may favor competitive advantage over methanogenesis, making them prospective candidates for competing with methanogens in ruminant animals.
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Affiliation(s)
- Supriya Karekar
- Bioproducts Science and Engineering Laboratory, Washington State University Tri-Cities, 2720 Crimson Way, Richland, WA 99354, USA; (S.K.); (R.S.)
- Department of Biological Systems Engineering, Washington State University, Pullman, WA 99163, USA
| | - Renan Stefanini
- Bioproducts Science and Engineering Laboratory, Washington State University Tri-Cities, 2720 Crimson Way, Richland, WA 99354, USA; (S.K.); (R.S.)
- Department of Biological Systems Engineering, Washington State University, Pullman, WA 99163, USA
| | - Birgitte Ahring
- Bioproducts Science and Engineering Laboratory, Washington State University Tri-Cities, 2720 Crimson Way, Richland, WA 99354, USA; (S.K.); (R.S.)
- Department of Biological Systems Engineering, Washington State University, Pullman, WA 99163, USA
- The Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99163, USA
- Correspondence:
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Methanogenesis in the Digestive Tracts of the Tropical Millipedes Archispirostreptus gigas (Diplopoda, Spirostreptidae) and Epibolus pulchripes (Diplopoda, Pachybolidae). Appl Environ Microbiol 2021; 87:e0061421. [PMID: 34020937 DOI: 10.1128/aem.00614-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methanogens represent the final decomposition step in anaerobic degradation of organic matter, occurring in the digestive tracts of various invertebrates. However, factors determining their community structure and activity in distinct gut sections are still debated. In this study, we focused on the tropical millipede species Archispirostreptus gigas (Diplopoda, Spirostreptidae) and Epibolus pulchripes (Diplopoda, Pachybolidae), which release considerable amounts of methane. We aimed to characterize relationships between physicochemical parameters, methane production rates, and methanogen community structure in the two major gut sections, midgut and hindgut. Microsensor measurements revealed that both sections were strictly anoxic, with reducing conditions prevailing in both millipedes. Hydrogen concentration peaked in the anterior hindgut of E. pulchripes. In both species, the intestinal pH was significantly higher in the hindgut than in the midgut. An accumulation of acetate and formate in the gut indicated bacterial fermentation activities in the digestive tracts of both species. Phylogenetic analysis of 16S rRNA genes showed a prevalence of Methanobrevibacter spp. (Methanobacteriales), accompanied by a small fraction of so-far-unclassified "Methanomethylophilaceae" (Methanomassiliicoccales), in both species, which suggests that methanogenesis is mostly hydrogenotrophic. We conclude that anoxic conditions, negative redox potential, and bacterial production of hydrogen and formate promote gut colonization by methanogens. The higher activities of methanogens in the hindgut are explained by the higher pH of this compartment and their association with ciliates, which are restricted to this compartment and present an additional source of methanogenic substrates. IMPORTANCE Methane (CH4) is the second most important atmospheric greenhouse gas after CO2 and is believed to account for 17% of global warming. Methanogens are a diverse group of archaea and can be found in various anoxic habitats, including digestive tracts of plant-feeding animals. Termites, cockroaches, the larvae of scarab beetles, and millipedes are the only arthropods known to host methanogens and emit large amounts of methane. Millipedes are ranked as the third most important detritivores after termites and earthworms, and they are considered keystone species in many terrestrial ecosystems. Both methane-producing and non-methane-emitting species of millipedes have been observed, but what limits their methanogenic potential is not known. In the present study, we show that physicochemical gut conditions and the distribution of symbiotic ciliates are important factors determining CH4 emission in millipedes. We also found close similarities to other methane-emitting arthropods, which might be associated with their similar plant-feeding habits.
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Callegari M, Crotti E, Fusi M, Marasco R, Gonella E, De Noni I, Romano D, Borin S, Tsiamis G, Cherif A, Alma A, Daffonchio D. Compartmentalization of bacterial and fungal microbiomes in the gut of adult honeybees. NPJ Biofilms Microbiomes 2021; 7:42. [PMID: 33963194 PMCID: PMC8105395 DOI: 10.1038/s41522-021-00212-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 03/23/2021] [Indexed: 02/07/2023] Open
Abstract
The core gut microbiome of adult honeybee comprises a set of recurring bacterial phylotypes, accompanied by lineage-specific, variable, and less abundant environmental bacterial phylotypes. Several mutual interactions and functional services to the host, including the support provided for growth, hormonal signaling, and behavior, are attributed to the core and lineage-specific taxa. By contrast, the diversity and distribution of the minor environmental phylotypes and fungal members in the gut remain overlooked. In the present study, we hypothesized that the microbial components of forager honeybees (i.e., core bacteria, minor environmental phylotypes, and fungal members) are compartmentalized along the gut portions. The diversity and distribution of such three microbial components were investigated in the context of the physico-chemical conditions of different gut compartments. We observed that changes in the distribution and abundance of microbial components in the gut are consistently compartment-specific for all the three microbial components, indicating that the ecological and physiological interactions among the host and microbiome vary with changing physico-chemical and metabolic conditions of the gut.
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Affiliation(s)
- Matteo Callegari
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Elena Crotti
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, Milan, Italy.
| | - Marco Fusi
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, UK
| | - Ramona Marasco
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Elena Gonella
- Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, Grugliasco, Italy
| | - Ivano De Noni
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, Milan, Italy
| | - Diego Romano
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, Milan, Italy
| | - Sara Borin
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, Milan, Italy
| | - George Tsiamis
- Department of Environmental Engineering, University of Patras, Agrinion, Greece
| | - Ameur Cherif
- Institut Supérieur de Biotechnologie Sidi Thabet (ISBST), BVBGR-LR11ES31, Biotechpole Sidi Thabet, University Manouba, Ariana, Tunisia
| | - Alberto Alma
- Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, Grugliasco, Italy
| | - Daniele Daffonchio
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
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Kulikova NA, Perminova IV. Interactions between Humic Substances and Microorganisms and Their Implications for Nature-like Bioremediation Technologies. Molecules 2021; 26:2706. [PMID: 34063010 PMCID: PMC8124324 DOI: 10.3390/molecules26092706] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/02/2021] [Accepted: 05/02/2021] [Indexed: 12/22/2022] Open
Abstract
The state of the art of the reported data on interactions between microorganisms and HSs is presented herein. The properties of HSs are discussed in terms of microbial utilization, degradation, and transformation. The data on biologically active individual compounds found in HSs are summarized. Bacteria of the phylum Proteobacteria and fungi of the phyla Basidiomycota and Ascomycota were found to be the main HS degraders, while Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes were found to be the predominant phyla in humic-reducing microorganisms (HRMs). Some promising aspects of interactions between microorganisms and HSs are discussed as a feasible basis for nature-like biotechnologies, including the production of enzymes capable of catalyzing the oxidative binding of organic pollutants to HSs, while electron shuttling through the utilization of HSs by HRMs as electron shuttles may be used for the enhancement of organic pollutant biodegradation or lowering bioavailability of some metals. Utilization of HSs by HRMs as terminal electron acceptors may suppress electron transfer to CO2, reducing the formation of CH4 in temporarily anoxic systems. The data reported so far are mostly related to the use of HSs as redox compounds. HSs are capable of altering the composition of the microbial community, and there are environmental conditions that determine the efficiency of HSs. To facilitate the development of HS-based technologies, complex studies addressing these factors are in demand.
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Affiliation(s)
- Natalia A. Kulikova
- Department of Soil Science, Lomonosov Moscow State University, Leninskiye Gory 1-12, 119991 Moscow, Russia;
- Bach Institute of Biochemistry, Fundamentals of Biotechnology Federal Research Center, Russian Academy of Sciences, pr. Leninskiy 33, 119071 Moscow, Russia
| | - Irina V. Perminova
- Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, 119991 Moscow, Russia
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An Innovative in Situ Monitoring of Sulfate Reduction within a Wastewater Biofilm by H 2S and SO 42- Microsensors. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17062023. [PMID: 32204360 PMCID: PMC7142855 DOI: 10.3390/ijerph17062023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/07/2020] [Accepted: 03/16/2020] [Indexed: 11/17/2022]
Abstract
Microelectrodes can be used to obtain chemical profiles within biofilm microenvironments. For example, sulfate (SO42-) and hydrogen sulfide (H2S) microelectrodes can be used to study sulfate reduction activity in this context. However, there is no SO42- microelectrode available for studying sulfate reduction in biofilms. In this study, SO42- and H2S microelectrodes were fabricated and applied in the measurement of a wastewater membrane-aerated biofilm (MAB) to investigate the in situ sulfate reduction activity. Both the SO42- and H2S microelectrodes with a tip diameter of around 20 micrometers were successfully developed and displayed satisfying selectivity to SO42- and H2S, respectively. The Nernstian slopes of calibration curves of the fabricated SO42- electrodes were close to -28.1 mV/decade, and the R2 values were greater than 98%. Within the selected concentration range from 10-5 M (0.96 mg/L) to 10-2 M (960 mg/L), the response of the SO42- microelectrode was log-linearly related to its concentration. The successfully fabricated SO42- microelectrode was combined with the existing H2S microelectrode and applied on an environmental wastewater biofilm sample to investigate the sulfate reduction activity within it. The H2S and SO42- microelectrodes showed stable responses and good performance, and the decrease of SO42- with an accompanying increased of H2S within the biofilm indicated the in situ sulfate reduction activity. The application of combined SO42- and H2S microelectrodes in wastewater biofilms could amend the current understanding of sulfate reduction and sulfur oxidation within environmental biofilms based on only H2S microelectrodes.
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11
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Stefanini I. Yeast-insect associations: It takes guts. Yeast 2018; 35:315-330. [PMID: 29363168 PMCID: PMC5947625 DOI: 10.1002/yea.3309] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 12/02/2017] [Accepted: 12/27/2017] [Indexed: 01/08/2023] Open
Abstract
Insects interact with microorganisms in several situations, ranging from the accidental interaction to locate attractive food or the acquisition of essential nutrients missing in the main food source. Despite a wealth of studies recently focused on bacteria, the interactions between insects and yeasts have relevant implications for both of the parties involved. The insect intestine shows several structural and physiological differences among species, but it is generally a hostile environment for many microorganisms, selecting against the most sensitive and at the same time guaranteeing a less competitive environment to resistant ones. An intensive characterization of the interactions between yeasts and insects has highlighted their relevance not only for attraction to food but also for the insect's development and behaviour. Conversely, some yeasts have been shown to benefit from interactions with insects, in some cases by being carried among different environments. In addition, the insect intestine may provide a place to reside for prolonged periods and possibly mate or generate sexual forms able to mate once back in the external environments. YEA-May-17-0084.R3.
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Affiliation(s)
- Irene Stefanini
- Division of Biomedical SciencesUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
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12
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Brune A. Methanogens in the Digestive Tract of Termites. (ENDO)SYMBIOTIC METHANOGENIC ARCHAEA 2018. [DOI: 10.1007/978-3-319-98836-8_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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13
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Mikaelyan A, Thompson CL, Meuser K, Zheng H, Rani P, Plarre R, Brune A. High-resolution phylogenetic analysis of Endomicrobia reveals multiple acquisitions of endosymbiotic lineages by termite gut flagellates. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:477-483. [PMID: 28677262 DOI: 10.1111/1758-2229.12565] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 06/09/2017] [Accepted: 06/21/2017] [Indexed: 05/25/2023]
Abstract
Bacteria of the class Endomicrobia form a deep-branching clade in the Elusimicrobia phylum. They are found almost exclusively in the intestinal tract of animals and are particularly abundant in many termites, where they reside as intracellular symbionts in the cellulolytic gut flagellates. Although small populations of putatively free-living lineages have been detected in faunated and flagellate-free hosts, the evolutionary origin of the endosymbionts is obscured by the limited amount of phylogenetic information provided by the 16S rRNA gene fragment amplified with Endomicrobia-specific primers. Here, we present a robust phylogenetic framework based on the near-full-length 16S-23S rRNA gene region of a diverse set of Endomicrobia from termites and cockroaches, which also allowed us to classify the shorter reads from previous studies. Our data revealed that endosymbionts arose independently at least four times from different free-living lineages, which were already present in ancestral cockroaches but became associated with their respective hosts long after the digestive symbiosis between termites and flagellates had been established. Pyrotag sequencing revealed that the proportion of putatively free-living lineages increased, when all flagellates and their symbionts were removed from the gut of lower termites by starvation, starch feeding or hyperbaric oxygen, but results varied between different methods.
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Affiliation(s)
- Aram Mikaelyan
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
| | - Claire L Thompson
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
| | - Katja Meuser
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
| | - Hao Zheng
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
| | - Pinki Rani
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
| | - Rudy Plarre
- Federal Institute for Materials Research and Testing, Unter den Eichen 87, Berlin 12205, Germany
| | - Andreas Brune
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, Marburg 35043, Germany
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14
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Kuwahara H, Yuki M, Izawa K, Ohkuma M, Hongoh Y. Genome of 'Ca. Desulfovibrio trichonymphae', an H 2-oxidizing bacterium in a tripartite symbiotic system within a protist cell in the termite gut. ISME JOURNAL 2016; 11:766-776. [PMID: 27801909 PMCID: PMC5322295 DOI: 10.1038/ismej.2016.143] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/19/2016] [Accepted: 09/02/2016] [Indexed: 11/23/2022]
Abstract
The cellulolytic protist Trichonympha agilis in the termite gut permanently hosts two symbiotic bacteria, ‘Candidatus Endomicrobium trichonymphae' and ‘Candidatus Desulfovibrio trichonymphae'. The former is an intracellular symbiont, and the latter is almost intracellular but still connected to the outside via a small pore. The complete genome of ‘Ca. Endomicrobium trichonymphae' has previously been reported, and we here present the complete genome of ‘Ca. Desulfovibrio trichonymphae'. The genome is small (1 410 056 bp), has many pseudogenes, and retains biosynthetic pathways for various amino acids and cofactors, which are partially complementary to those of ‘Ca. Endomicrobium trichonymphae'. An amino acid permease gene has apparently been transferred between the ancestors of these two symbionts; a lateral gene transfer has affected their metabolic capacity. Notably, ‘Ca. Desulfovibrio trichonymphae' retains the complex system to oxidize hydrogen by sulfate and/or fumarate, while genes for utilizing other substrates common in desulfovibrios are pseudogenized or missing. Thus, ‘Ca. Desulfovibrio trichonymphae' is specialized to consume hydrogen that may otherwise inhibit fermentation processes in both T. agilis and ‘Ca. Endomicrobium trichonymphae'. The small pore may be necessary to take up sulfate. This study depicts a genome-based model of a multipartite symbiotic system within a cellulolytic protist cell in the termite gut.
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Affiliation(s)
- Hirokazu Kuwahara
- Department of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Masahiro Yuki
- Biomass Research Platform Team, RIKEN Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science, Tsukuba, Japan
| | - Kazuki Izawa
- Department of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Moriya Ohkuma
- Biomass Research Platform Team, RIKEN Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science, Tsukuba, Japan.,Japan Collection of Microorganisms, RIKEN BioResource Center, Tsukuba, Japan
| | - Yuichi Hongoh
- Department of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Japan Collection of Microorganisms, RIKEN BioResource Center, Tsukuba, Japan
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15
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Tegtmeier D, Thompson CL, Schauer C, Brune A. Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model. Appl Environ Microbiol 2016; 82:1080-1089. [PMID: 26637604 PMCID: PMC4751835 DOI: 10.1128/aem.03130-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022] Open
Abstract
The gut microbiota of termites and cockroaches represents complex metabolic networks of many diverse microbial populations. The distinct microenvironmental conditions within the gut and possible interactions among the microorganisms make it essential to investigate how far the metabolic properties of pure cultures reflect their activities in their natural environment. We established the cockroach Shelfordella lateralis as a gnotobiotic model and inoculated germfree nymphs with two bacterial strains isolated from the guts of conventional cockroaches. Fluorescence microscopy revealed that both strains specifically colonized the germfree hindgut. In diassociated cockroaches, the facultatively anaerobic strain EbSL (a new species of Enterobacteriaceae) always outnumbered the obligately anaerobic strain FuSL (a close relative of Fusobacterium varium), irrespective of the sequence of inoculation, which showed that precolonization by facultatively anaerobic bacteria does not necessarily favor colonization by obligate anaerobes. Comparison of the fermentation products of the cultures formed in vitro with those accumulated in situ indicated that the gut environment strongly affected the metabolic activities of both strains. The pure cultures formed the typical products of mixed-acid or butyrate fermentation, whereas the guts of gnotobiotic cockroaches accumulated mostly lactate and acetate. Similar shifts toward more-oxidized products were observed when the pure cultures were exposed to oxygen, which corroborated the strong effects of oxygen on the metabolic fluxes previously observed in termite guts. Oxygen microsensor profiles of the guts of germfree, gnotobiotic, and conventional cockroaches indicated that both gut tissue and microbiota contribute to oxygen consumption and suggest that the oxygen status influences the colonization success.
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Affiliation(s)
- Dorothee Tegtmeier
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Claire L Thompson
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Christine Schauer
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Andreas Brune
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
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16
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Nielsen M, Revsbech NP, Kühl M. Microsensor measurements of hydrogen gas dynamics in cyanobacterial microbial mats. Front Microbiol 2015; 6:726. [PMID: 26257714 PMCID: PMC4508582 DOI: 10.3389/fmicb.2015.00726] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/02/2015] [Indexed: 11/16/2022] Open
Abstract
We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria sp.). The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5–5 pA per μmol L-1 H2). Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8–10% H2 saturation) within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1–2 h in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct biophotolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g., sulfate reduction or anoxygenic photosynthesis in microbial mats.
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Affiliation(s)
- Michael Nielsen
- Section of Microbiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Niels P Revsbech
- Section of Microbiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen Helsingør, Denmark ; Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Ultimo NSW, Australia
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17
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Hoffmann D, Maldonado J, Wojciechowski MF, Garcia-Pichel F. Hydrogen export from intertidal cyanobacterial mats: sources, fluxes and the influence of community composition. Environ Microbiol 2015; 17:3738-53. [DOI: 10.1111/1462-2920.12769] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 12/23/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Dörte Hoffmann
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
| | - Juan Maldonado
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
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18
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Tarayre C, Bauwens J, Brasseur C, Mattéotti C, Millet C, Guiot PA, Destain J, Vandenbol M, Portetelle D, De Pauw E, Haubruge E, Francis F, Thonart P. Isolation and cultivation of xylanolytic and cellulolytic Sarocladium kiliense and Trichoderma virens from the gut of the termite Reticulitermes santonensis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:4369-4382. [PMID: 25300185 DOI: 10.1007/s11356-014-3681-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 10/01/2014] [Indexed: 06/04/2023]
Abstract
The purpose of this work was the isolation and cultivation of cellulolytic and xylanolytic microorganisms extracted from the gut of the lower termite Reticulitermes santonensis. Microcrystalline cellulose (with and without lignin) and beech wood xylan were used as diets instead of poplar wood in order to select cellulose and hemicellulose-degrading fungi. The strain Sarocladium kiliense (Acremonium kiliense) CTGxxyl was isolated from the termites fed on xylan, while the strain Trichoderma virens CTGxAviL was isolated from the termites fed on cellulose (with and without lignin). Both molds were cultivated in liquid media containing different substrates: agro-residues or purified polymers. S. kiliense produced maximal β-glucosidase, endo-1,4-β-D-glucanase, exo-1,4-β-D-glucanase and endo-1,4-β-D-xylanase activities of 0.103, 3.99, 0.53, and 40.8 IU/ml, respectively. T. virens produced maximal β-xylosidase, endo-1,4-β-D-glucanase, exo-1,4-β-D-glucanase, and endo-1,4-β-D-xylanase activities of 0.38, 1.48, 0.69, and 426 IU/ml. The cellulase and the xylanase of S. kiliense, less common than T. virens, were further investigated. The optimal activity of the xylanase was observed at pH 9-10 at 60 °C. The cellulase showed its maximal activity at pH 10, 70 °C. Zymography identified different xylanases produced by both molds, and some fragment sizes were highlighted: 35, 100, and 170 kDa for S. kiliense and 20, 40, 80, and 170 kDa for T. virens. In both cases, endo-1,4-β-D-xylanase activities were confirmed through mass spectrometry.
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Affiliation(s)
- Cédric Tarayre
- Unit of Bio-Industries, Gembloux Agro-Bio Tech, University of Liège, 5030, Gembloux, Belgium,
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19
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Kothari A, Parameswaran P, Garcia-Pichel F. Powerful fermentative hydrogen evolution of photosynthate in the cyanobacterium Lyngbya aestuarii BL J mediated by a bidirectional hydrogenase. Front Microbiol 2014; 5:680. [PMID: 25540642 PMCID: PMC4261827 DOI: 10.3389/fmicb.2014.00680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/20/2014] [Indexed: 11/25/2022] Open
Abstract
Cyanobacteria are considered good models for biohydrogen production because they are relatively simple organisms with a demonstrable ability to generate H2 under certain physiological conditions. However, most produce only little H2, revert readily to H2 consumption, and suffer from hydrogenase sensitivity to O2. Strains of the cyanobacteria Lyngbya aestuarii and Microcoleus chthonoplastes obtained from marine intertidal cyanobacterial mats were recently found to display much better H2 production potential. Because of their ecological origin in environments that become quickly anoxic in the dark, we hypothesized that this differential ability may have evolved to serve a role in the fermentation of the photosynthate. Here we show that, when forced to ferment internal substrate, these cyanobacteria display desirable characteristics of physiological H2 production. Among them, the strain L. aestuarii BL J had the fastest specific rates and attained the highest H2 concentrations during fermentation of photosynthate, which proceeded via a mixed acid fermentation pathway to yield acetate, ethanol, lactate, H2, CO2, and pyruvate. Contrary to expectations, the H2 yield per mole of glucose was only average compared to that of other cyanobacteria. Thermodynamic analyses point to the use of electron donors more electronegative than NAD(P)H in Lyngbya hydrogenases as the basis for its strong H2 production ability. In any event, the high specific rates and H2 concentrations coupled with the lack of reversibility of the enzyme, at the expense of internal, photosynthetically generated reductants, makes L. aestuarii BL J and/or its enzymes, a potentially feasible platform for large-scale H2 production.
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Affiliation(s)
- Ankita Kothari
- School of Life Sciences, Arizona State University Tempe, AZ, USA
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20
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Bauer E, Lampert N, Mikaelyan A, Köhler T, Maekawa K, Brune A. Physicochemical conditions, metabolites and community structure of the bacterial microbiota in the gut of wood-feeding cockroaches (Blaberidae: Panesthiinae). FEMS Microbiol Ecol 2014; 91:1-14. [PMID: 25764554 DOI: 10.1093/femsec/fiu028] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While the gut microbiota of termites and its role in symbiotic digestion have been studied for decades, little is known about the bacteria colonizing the intestinal tract of the distantly related wood-feeding cockroaches (Blaberidae: Panesthiinae). Here, we show that physicochemical gut conditions and microbial fermentation products in the gut of Panesthia angustipennis resemble that of other cockroaches. Microsensor measurements confirmed that all gut compartments were anoxic at the center and had a slightly acidic to neutral pH and a negative redox potential. While acetate dominated in all compartments, lactate and hydrogen accumulated only in the crop. The high, hydrogen-limited rates of methane emission from living cockroaches were in agreement with the restriction of F420-fluorescent methanogens to the hindgut. The gut microbiota of both P. angustipennis and Salganea esakii differed strongly between compartments, with the highest density and diversity in the hindgut, but similarities between homologous compartments of both cockroaches indicated a specificity of the microbiota for their respective habitats. While some lineages were most closely related to the gut microbiota of omnivorous cockroaches and wood- or litter-feeding termites, others have been encountered also in vertebrates, reinforcing the hypothesis that strong environmental selection drives community structure in the cockroach gut.
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Affiliation(s)
- Eugen Bauer
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Niclas Lampert
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Aram Mikaelyan
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Tim Köhler
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Kiyoto Maekawa
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Andreas Brune
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
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21
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The role of host phylogeny varies in shaping microbial diversity in the hindguts of lower termites. Appl Environ Microbiol 2014; 81:1059-70. [PMID: 25452280 DOI: 10.1128/aem.02945-14] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The hindguts of lower termites and Cryptocercus cockroaches are home to a distinct community of archaea, bacteria, and protists (primarily parabasalids and some oxymonads). Within a host species, the composition of these hindgut communities appears relatively stable, but the evolutionary and ecological factors structuring community composition and stability are poorly understood, as are differential impacts of these factors on protists, bacteria, and archaea. We analyzed the microbial composition of parabasalids and bacteria in the hindguts of Cryptocercus punctulatus and 23 species spanning 4 families of lower termites by pyrosequencing variable regions of the small-subunit rRNA gene. Especially for the parabasalids, these data revealed undiscovered taxa and provided a phylogenetic basis for a more accurate understanding of diversity, diversification, and community composition. The composition of the parabasalid communities was found to be strongly structured by the phylogeny of their hosts, indicating the importance of historical effects, although exceptions were also identified. Particularly, spirotrichonymphids and trichonymphids likely were transferred between host lineages. In contrast, host phylogeny was not sufficient to explain the majority of bacterial community composition, but the compositions of the Bacteroidetes, Elusimicrobia, Tenericutes, Spirochaetes, and Synergistes were structured by host phylogeny perhaps due to their symbiotic associations with protists. All together, historical effects probably resulting from vertical inheritance have had a prominent role in structuring the hindgut communities, especially of the parabasalids, but dispersal and environmental acquisition have played a larger role in community composition than previously expected.
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22
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Rosengaus RB, Schultheis KF, Yalonetskaya A, Bulmer MS, DuComb WS, Benson RW, Thottam JP, Godoy-Carter V. Symbiont-derived β-1,3-glucanases in a social insect: mutualism beyond nutrition. Front Microbiol 2014; 5:607. [PMID: 25484878 PMCID: PMC4240165 DOI: 10.3389/fmicb.2014.00607] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/24/2014] [Indexed: 11/17/2022] Open
Abstract
Termites have had a long co-evolutionary history with prokaryotic and eukaryotic gut microbes. Historically, the role of these anaerobic obligate symbionts has been attributed to the nutritional welfare of the host. We provide evidence that protozoa (and/or their associated bacteria) colonizing the hindgut of the dampwood termite Zootermopsis angusticollis, synthesize multiple functional β-1,3-glucanases, enzymes known for breaking down β-1,3-glucans, the main component of fungal cell walls. These enzymes, we propose, may help in both digestion of ingested fungal hyphae and protection against invasion by fungal pathogens. This research points to an additional novel role for the mutualistic hindgut microbial consortia of termites, an association that may extend beyond lignocellulolytic activity and nitrogen fixation to include a reduction in the risks of mycosis at both the individual- and colony-levels while nesting in and feeding on microbial-rich decayed wood.
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Affiliation(s)
- Rebeca B. Rosengaus
- Department of Marine and Environmental Sciences, Northeastern UniversityBoston, MA, USA
| | - Kelley F. Schultheis
- Department of Marine and Environmental Sciences, Northeastern UniversityBoston, MA, USA
| | - Alla Yalonetskaya
- Department of Marine and Environmental Sciences, Northeastern UniversityBoston, MA, USA
| | - Mark S. Bulmer
- Department of Biological Sciences, Towson UniversityTowson, MD, USA
| | | | - Ryan W. Benson
- Department of Biology, Northeastern UniversityBoston, MA, USA
| | - John P. Thottam
- Department of Marine and Environmental Sciences, Northeastern UniversityBoston, MA, USA
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23
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Šustr V, Stingl U, Brune A. Microprofiles of oxygen, redox potential, and pH, and microbial fermentation products in the highly alkaline gut of the saprophagous larva of Penthetria holosericea (Diptera: Bibionidae). JOURNAL OF INSECT PHYSIOLOGY 2014; 67:64-69. [PMID: 24971929 DOI: 10.1016/j.jinsphys.2014.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 06/03/2023]
Abstract
The saprophagous larvae of bibionid flies harbor bacteria in their alkaline intestinal tracts, but little is known about the contribution of the gut microbiota to the digestion of their recalcitrant diet. In this study, we measured oxygen and hydrogen partial pressure, redox potential and pH in the midgut, gastric caeca and hindgut of larvae of the bibionid fly Penthetria holosericea with Clark-type O2 and H2 microsensors, platinum redox microelectrodes, and LIX-type pH microelectrodes. The center of the midgut lumen was anoxic, whereas gastric caeca and hindgut were hypoxic. However, redox potential profiles indicated oxidizing conditions throughout the gut, with lowest values in the midgut (+20 to +60mV). Hydrogen production was not detected. The midgut was extremely alkaline (pH around 11), whereas hindgut and gastric caeca were neutral to slightly alkaline. While HPLC analysis showed high concentrations of glucose in the midgut (15mM) and gastric caeca (27mM), the concentrations of microbial fermentation products such as lactate (2-4mM), acetate (<1mM) and succinate (<0.5mM) were low in all gut regions, suggesting that the contribution of microorganisms to the digestive process, particularly in the alkaline midgut, is only of minor importance. We conclude that the digestive strategy of the saprophytic larva of P. holosericea, which feeds selectively on decomposed leaves and its own microbe-rich faeces, differs fundamentally from those of detritivorous and humivorous insects, which host a highly active, fermentative microbiota in their alkaline midgut or hindgut compartments.
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Affiliation(s)
- Vladimír Šustr
- Institute of Soil Biology, Biology Centre, Academy of Sciences of the Czech Republic, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
| | - Ulrich Stingl
- Mikrobielle Ökologie, Fachbereich Biologie, Universität Konstanz, 78434 Konstanz, Germany
| | - Andreas Brune
- Mikrobielle Ökologie, Fachbereich Biologie, Universität Konstanz, 78434 Konstanz, Germany; Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043 Marburg, Germany
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24
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Insect gut bacterial diversity determined by environmental habitat, diet, developmental stage, and phylogeny of host. Appl Environ Microbiol 2014; 80:5254-64. [PMID: 24928884 DOI: 10.1128/aem.01226-14] [Citation(s) in RCA: 421] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Insects are the most abundant animals on Earth, and the microbiota within their guts play important roles by engaging in beneficial and pathological interactions with these hosts. In this study, we comprehensively characterized insect-associated gut bacteria of 305 individuals belonging to 218 species in 21 taxonomic orders, using 454 pyrosequencing of 16S rRNA genes. In total, 174,374 sequence reads were obtained, identifying 9,301 bacterial operational taxonomic units (OTUs) at the 3% distance level from all samples, with an average of 84.3 (± 97.7) OTUs per sample. The insect gut microbiota were dominated by Proteobacteria (62.1% of the total reads, including 14.1% Wolbachia sequences) and Firmicutes (20.7%). Significant differences were found in the relative abundances of anaerobes in insects and were classified according to the criteria of host environmental habitat, diet, developmental stage, and phylogeny. Gut bacterial diversity was significantly higher in omnivorous insects than in stenophagous (carnivorous and herbivorous) insects. This insect-order-spanning investigation of the gut microbiota provides insights into the relationships between insects and their gut bacterial communities.
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Xue J, Shang G, Tanaka Y, Saihara Y, Hou L, Velasquez N, Liu W, Lu Y. Dose-dependent inhibition of gastric injury by hydrogen in alkaline electrolyzed drinking water. Altern Ther Health Med 2014; 14:81. [PMID: 24589018 PMCID: PMC3944674 DOI: 10.1186/1472-6882-14-81] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 02/25/2014] [Indexed: 12/20/2022]
Abstract
Background Hydrogen has been reported to relieve damage in many disease models, and is a potential additive in drinking water to provide protective effects for patients as several clinical studies revealed. However, the absence of a dose–response relationship in the application of hydrogen is puzzling. We attempted to identify the dose–response relationship of hydrogen in alkaline electrolyzed drinking water through the aspirin induced gastric injury model. Methods In this study, hydrogen-rich alkaline water was obtained by adding H2 to electrolyzed water at one atmosphere pressure. After 2 weeks of drinking, we detected the gastric mucosal damage together with MPO, MDA and 8-OHdG in rat aspirin induced gastric injury model. Results Hydrogen-dose dependent inhibition was observed in stomach mucosal. Under pH 8.5, 0.07, 0.22 and 0.84 ppm hydrogen exhibited a high correlation with inhibitory effects showed by erosion area, MPO activity and MDA content in the stomach. Gastric histology also demonstrated the inhibition of damage by hydrogen-rich alkaline water. However, 8-OHdG level in serum did not have significant hydrogen-dose dependent effect. pH 9.5 showed higher but not significant inhibitory response compared with pH 8.5. Conclusions Hydrogen is effective in relieving the gastric injury induced by aspirin-HCl, and the inhibitory effect is dose-dependent. The reason behind this may be that hydrogen-rich water directly interacted with the target tissue, while the hydrogen concentration in blood was buffered by liver glycogen, evoking a suppressed dose–response effect. Drinking hydrogen-rich water may protect healthy individuals from gastric damage caused by oxidative stress.
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Kothari A, Vaughn M, Garcia-Pichel F. Comparative genomic analyses of the cyanobacterium, Lyngbya aestuarii BL J, a powerful hydrogen producer. Front Microbiol 2013; 4:363. [PMID: 24376438 PMCID: PMC3858816 DOI: 10.3389/fmicb.2013.00363] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 11/15/2013] [Indexed: 11/13/2022] Open
Abstract
The filamentous, non-heterocystous cyanobacterium Lyngbya aestuarii is an important contributor to marine intertidal microbial mats system worldwide. The recent isolate L. aestuarii BL J, is an unusually powerful hydrogen producer. Here we report a morphological, ultrastructural, and genomic characterization of this strain to set the basis for future systems studies and applications of this organism. The filaments contain circa 17 μm wide trichomes, composed of stacked disk-like short cells (2 μm long), encased in a prominent, laminated exopolysaccharide sheath. Cellular division occurs by transversal centripetal growth of cross-walls, where several rounds of division proceed simultaneously. Filament division occurs by cell self-immolation of one or groups of cells (necridial cells) at the breakage point. Short, sheath-less, motile filaments (hormogonia) are also formed. Morphologically and phylogenetically L. aestuarii belongs to a clade of important cyanobacteria that include members of the marine Trichodesmiun and Hydrocoleum genera, as well as terrestrial Microcoleus vaginatus strains, and alkalyphilic strains of Arthrospira. A draft genome of strain BL J was compared to those of other cyanobacteria in order to ascertain some of its ecological constraints and biotechnological potential. The genome had an average GC content of 41.1%. Of the 6.87 Mb sequenced, 6.44 Mb was present as large contigs (>10,000 bp). It contained 6515 putative protein-encoding genes, of which, 43% encode proteins of known functional role, 26% corresponded to proteins with domain or family assignments, 19.6% encode conserved hypothetical proteins, and 11.3% encode apparently unique hypothetical proteins. The strain's genome reveals its adaptations to a life of exposure to intense solar radiation and desiccation. It likely employs the storage compounds, glycogen, and cyanophycin but no polyhydroxyalkanoates, and can produce the osmolytes, trehalose, and glycine betaine. According to its genome, BL J strain also has the potential to produce a plethora of products of biotechnological interest such as Curacin A, Barbamide, Hemolysin-type calcium-binding toxin, the suncreens scytonemin, and mycosporines, as well as heptadecane and pentadecane alkanes. With respect to hydrogen production, initial comparisons of the genetic architecture and sequence of relevant genes and loci, and a comparative model of protein structure of the NiFe bidirectional hydrogenase, did not reveal conspicuous differences that could explain its unusual hydrogen producing capacity.
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Affiliation(s)
- Ankita Kothari
- School of Life Sciences, Arizona State University Tempe, AZ, USA
| | - Michael Vaughn
- Department of Chemistry and Biochemistry, Arizona State University Tempe, AZ, USA
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Ungerfeld EM. A theoretical comparison between two ruminal electron sinks. Front Microbiol 2013; 4:319. [PMID: 24198813 PMCID: PMC3812538 DOI: 10.3389/fmicb.2013.00319] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/10/2013] [Indexed: 11/13/2022] Open
Abstract
Dihydrogen accumulation resulting from methanogenesis inhibition in the rumen is an energy loss and can inhibit fermentation. The objective of this analysis was to compare the energetic and nutritional consequences of incorporating H2 into reductive acetogenesis or additional propionate production beyond the acetate to propionate shift occurring along with methanogenesis inhibition. Stoichiometric consequences were calculated for a simulated fermentation example. Possible nutritional consequences are discussed. Incorporating H2 into reductive acetogenesis or additional propionate production resulted in equal heat of combustion output in volatile fatty acids (VFA). Incorporation of H2 into reductive acetogenesis could result in moderate decrease in ruminal pH, although whole-animal buffering mechanisms make pH response difficult to predict. Research would be needed to compare the microbial protein production output. There could be post-absorptive implications due to differences in VFA profile. Electron incorporation into reductive acetogenesis could favor energy partition toward milk, but increase risk of ketosis in high-producing dairy cows on ketogenic diets. Greater propionate production could favor milk protein production, but may be less desirable in animals whose intake is metabolically constrained, like feedlot steers. Because of the different nutritional implications, and because practical solutions to incorporate H2 into either pathway are not yet available, it is recommended to research both alternatives.
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Affiliation(s)
- Emilio M. Ungerfeld
- CONICYT Regional R10C1002, Centro de Investigación y Desarrollo CIEN Austral, Universidad Austral de ChilePuerto Montt, Chile
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Engel P, Moran NA. The gut microbiota of insects – diversity in structure and function. FEMS Microbiol Rev 2013; 37:699-735. [DOI: 10.1111/1574-6976.12025] [Citation(s) in RCA: 1300] [Impact Index Per Article: 118.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 05/06/2013] [Accepted: 05/13/2013] [Indexed: 02/07/2023] Open
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Ceja-Navarro JA, Nguyen NH, Karaoz U, Gross SR, Herman DJ, Andersen GL, Bruns TD, Pett-Ridge J, Blackwell M, Brodie EL. Compartmentalized microbial composition, oxygen gradients and nitrogen fixation in the gut of Odontotaenius disjunctus. ISME JOURNAL 2013; 8:6-18. [PMID: 23985746 DOI: 10.1038/ismej.2013.134] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 07/03/2013] [Accepted: 07/13/2013] [Indexed: 11/09/2022]
Abstract
Coarse woody debris is an important biomass pool in forest ecosystems that numerous groups of insects have evolved to take advantage of. These insects are ecologically important and represent useful natural analogs for biomass to biofuel conversion. Using a range of molecular approaches combined with microelectrode measurements of oxygen, we have characterized the gut microbiome and physiology of Odontotaenius disjunctus, a wood-feeding beetle native to the eastern United States. We hypothesized that morphological and physiological differences among gut regions would correspond to distinct microbial populations and activities. In fact, significantly different communities were found in the foregut (FG), midgut (MG)/posterior hindgut (PHG) and anterior hindgut (AHG), with Actinobacteria and Rhizobiales being more abundant toward the FG and PHG. Conversely, fermentative bacteria such as Bacteroidetes and Clostridia were more abundant in the AHG, and also the sole region where methanogenic Archaea were detected. Although each gut region possessed an anaerobic core, micron-scale profiling identified radial gradients in oxygen concentration in all regions. Nitrogen fixation was confirmed by (15)N2 incorporation, and nitrogenase gene (nifH) expression was greatest in the AHG. Phylogenetic analysis of nifH identified the most abundant transcript as related to Ni-Fe nitrogenase of a Bacteroidetes species, Paludibacter propionicigenes. Overall, we demonstrate not only a compartmentalized microbiome in this beetle digestive tract but also sharp oxygen gradients that may permit aerobic and anaerobic metabolism to occur within the same regions in close proximity. We provide evidence for the microbial fixation of N2 that is important for this beetle to subsist on woody biomass.
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Affiliation(s)
- Javier A Ceja-Navarro
- Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nhu H Nguyen
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Ulas Karaoz
- Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Stephanie R Gross
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Donald J Herman
- Department of Environmental Science Policy and Management, University of California, Berkeley, CA, USA
| | - Gary L Andersen
- Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Thomas D Bruns
- Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jennifer Pett-Ridge
- Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Meredith Blackwell
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Eoin L Brodie
- 1] Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA [2] Department of Environmental Science Policy and Management, University of California, Berkeley, CA, USA
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König H, Li L, Fröhlich J. The cellulolytic system of the termite gut. Appl Microbiol Biotechnol 2013; 97:7943-62. [PMID: 23900801 DOI: 10.1007/s00253-013-5119-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/09/2013] [Accepted: 07/10/2013] [Indexed: 10/26/2022]
Abstract
The demand for the usage of natural renewable polymeric material is increasing in order to satisfy the future needs for energy and chemical precursors. Important steps in the hydrolysis of polymeric material and bioconversion can be performed by microorganisms. Over about 150 million years, termites have optimized their intestinal polysaccharide-degrading symbiosis. In the ecosystem of the "termite gut," polysaccharides are degraded from lignocellulose, such as cellulose and hemicelluloses, in 1 day, while lignin is only weakly attacked. The understanding of the principles of cellulose degradation in this natural polymer-degrading ecosystem could be helpful for the improvement of the biotechnological hydrolysis and conversion of cellulose, e.g., in the case of biogas production from natural renewable plant material in biogas plants. This review focuses on the present knowledge of the cellulose degradation in the termite gut.
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Affiliation(s)
- Helmut König
- Institute of Microbiology and Wine Research, Johannes Gutenberg University of Mainz, 55099, Mainz, Germany.
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Single-Cell DNA barcoding using sequences from the small subunit rRNA and internal transcribed spacer region identifies new species of Trichonympha and Trichomitopsis from the hindgut of the termite Zootermopsis angusticollis. PLoS One 2013; 8:e58728. [PMID: 23536818 PMCID: PMC3594152 DOI: 10.1371/journal.pone.0058728] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/05/2013] [Indexed: 11/19/2022] Open
Abstract
To aid in their digestion of wood, lower termites are known to harbour a diverse community of prokaryotes as well as parabasalid and oxymonad protist symbionts. One of the best-studied lower termite gut communities is that of Zootermopsis angusticollis which has been known for almost 100 years to possess 3 species of Trichonympha (T. campanula, T. collaris, and T. sphaerica), 1 species of Trichomitopsis (T. termopsidis), as well as smaller flagellates. We have re-assessed this community by sequencing the small subunit (SSU) rRNA gene and the internal transcribed spacer (ITS) region from a large number of single Trichonympha and Trichomitopsis cells for which morphology was also documented. Based on phylogenetic clustering and sequence divergence, we identify 3 new species: Trichonympha postcylindrica, Trichomitopsis minor, and Trichomitopsis parvus spp. nov. Once identified by sequencing, the morphology of the isolated cells for all 3 new species was re-examined and found to be distinct from the previously described species: Trichonympha postcylindrica can be morphologically distinguished from the other Trichonympha species by an extension on its posterior end, whereas Trichomitopsis minor and T. parvus are smaller than T. termopsidis but similar in size to each other and cannot be distinguished based on morphology using light microscopy. Given that Z. angusticollis has one of the best characterized hindgut communities, the near doubling of the number of the largest and most easily identifiable symbiont species suggests that the diversity of hindgut symbionts is substantially underestimated in other termites as well. Accurate descriptions of the diversity of these microbial communities are essential for understanding hindgut ecology and disentangling the interactions among the symbionts, and molecular barcoding should be a priority for these systems.
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Abstract
The main challenge in second generation bioethanol production is the efficient breakdown of cellulose to sugar monomers (hydrolysis). Due to the recalcitrant character of cellulose, feedstock pretreatment and adapted hydrolysis steps are needed to obtain fermentable sugar monomers. The conventional industrial production process of second-generation bioethanol from biomass comprises several steps: thermochemical pretreatment, enzymatic hydrolysis and sugar fermentation. This process is undergoing continuous optimization in order to increase the bioethanol yield and reduce the economic cost. Therefore, the discovery of new enzymes with high lignocellulytic activity or new strategies is extremely important. In nature, wood-feeding termites have developed a sophisticated and efficient cellulose degrading system in terms of the rate and extent of cellulose hydrolysis and exploitation. This system, which represents a model for digestive symbiosis has attracted the attention of biofuel researchers. This review describes the termite digestive system, gut symbionts, termite enzyme resources, in vitro studies of isolated enzymes and lignin degradation in termites.
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Li H, Sun J, Zhao J, Deng T, Lu J, Dong Y, Deng W, Mo J. Physicochemical conditions and metal ion profiles in the gut of the fungus-growing termite Odontotermes formosanus. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:1368-1375. [PMID: 22858833 DOI: 10.1016/j.jinsphys.2012.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 07/20/2012] [Accepted: 07/23/2012] [Indexed: 06/01/2023]
Abstract
The physicochemical conditions in an insect's gut microenvironment have been reported to play an important role in food processing and metabolisms. In this study, the profiles of oxygen, pH, redox potentials, and hydrogen in the isolated guts of the fungus-growing termite, Odontotermes formosanus Shiraki, were investigated with a microeletrode system. Compared with those in other termites, O. formosanus exhibited a relatively lower oxygen partial pressures in its gut system ranging from 0 to 8.6 kPa. The pH profile in the different gut compartments was neutral (pH 6.1-7.4) except in the rectum region. The average redox potentials at the center of each gut region (except rectum) were high and ranged from approximately +70 to +310 mV. Especially, as the central intermediate during lignocellulose degradation, hydrogen partial pressures in the hindgut paunch lumen were recorded as high as 10.4 kPa. Furthermore, thirteen metal ion concentrations in the termite's gut system, nest symbiotic fungal combs, as well as the nest soil samples were evaluated with Inductively Coupled Plasma Mass Spectrometry (ICP-MS), which indicated that six metal ions (K, Mg, Mn, Ba, Se, and Mo) out of 13 ions recorded in the major digestive tract regions show some significant differences in their spatial distributions. A significant enrichment of some metal ions was also observed in the rectum, fungal combs, and the nest soil samples. The lower oxygen profiles, neutral pH, higher redox potentials, and higher hydrogen accumulation with the characterized spatial distributions for metal ions in the digestive tract of O. formosanus, highlighted the most important distinctiveness of the fungus-growing termites in its gut microenvironments, suggesting that the unique structure and functions of the intestinal ecosystem may present within its gut.
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Affiliation(s)
- Hongjie Li
- Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, Zhejiang, PR China
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Tamschick S, Radek R. Colonization of termite hindgut walls by oxymonad flagellates and prokaryotes in Incisitermes tabogae, I. marginipennis and Reticulitermes flavipes. Eur J Protistol 2012; 49:1-14. [PMID: 22841421 DOI: 10.1016/j.ejop.2012.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 06/22/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022]
Abstract
We studied the colonization of the paunch wall of three lower termites, Reticulitermes flavipes, Incisitermes tabogae, and Incisitermes marginipennis, by light and electron microscopy. In addition to various prokaryotes, oxymonad flagellates were attached to the wall of the paunch in all three species. The prokaryotic layer found in R. flavipes is relatively thin, since most organisms are attached laterally. Large members of the flagellate genus Pyrsonympha protrude into the gut lumen. The prokaryotes are very abundant on the gut wall in I. tabogae and I. marginipennis, forming a thick carpet of mostly vertically attached rods and wavy spirochetes. The adhering oxymonads are relatively small and almost hidden in the thick bacterial biofilm. Three small morphotypes were seen in I. tabogae; two possessing a short rostellum and one amoeboid. The only oxymonad found in I. tabogae so far, Oxymonas clevelandi, is not identical to any of the present oxymonads. I. marginipennis contains a mid-sized oxymonad with ectobiotic spirochetes, probably identical to Oxymonas hubbardi, and a tiny unknown morphotype. The spatial organization of the pro- and eukaryotic microorganisms on the gut wall of the three termites is described and discussed concerning oxygen stress.
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Affiliation(s)
- Stephanie Tamschick
- Free University of Berlin, Institute of Biology/Zoology, Königin-Luise-Str. 1-3, 14195 Berlin, Germany
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Köhler T, Dietrich C, Scheffrahn RH, Brune A. High-resolution analysis of gut environment and bacterial microbiota reveals functional compartmentation of the gut in wood-feeding higher termites (Nasutitermes spp.). Appl Environ Microbiol 2012; 78:4691-701. [PMID: 22544239 PMCID: PMC3370480 DOI: 10.1128/aem.00683-12] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/13/2012] [Indexed: 11/20/2022] Open
Abstract
Higher termites are characterized by a purely prokaryotic gut microbiota and an increased compartmentation of their intestinal tract. In soil-feeding species, each gut compartment has different physicochemical conditions and is colonized by a specific microbial community. Although considerable information has accumulated also for wood-feeding species of the genus Nasutitermes, including cellulase activities and metagenomic data, a comprehensive study linking physicochemical gut conditions with the structure of the microbial communities in the different gut compartments is lacking. In this study, we measured high-resolution profiles of H(2), O(2), pH, and redox potential in the gut of Nasutitermes corniger termites, determined the fermentation products accumulating in the individual gut compartments, and analyzed the bacterial communities in detail by pyrotag sequencing of the V3-V4 region of the 16S rRNA genes. The dilated hindgut paunch (P3 compartment) was the only anoxic gut region, showed the highest density of bacteria, and accumulated H(2) to high partial pressures (up to 12 kPa). Molecular hydrogen is apparently produced by a dense community of Spirochaetes and Fibrobacteres, which also dominate the gut of other Nasutitermes species. All other compartments, such as the alkaline P1 compartment (average pH, 10.0), showed high redox potentials and comprised small but distinct populations characteristic for each gut region. In the crop and the posterior hindgut compartments, the community was even more diverse than in the paunch. Similarities in the communities of the posterior hindgut and crop suggested that proctodeal trophallaxis or coprophagy also occurs in higher termites. The large sampling depths of pyrotag sequencing in combination with the determination of important physicochemical parameters allow cautious conclusions concerning the functions of particular bacterial lineages in the respective gut sections to be drawn.
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Affiliation(s)
- Tim Köhler
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Carsten Dietrich
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Rudolf H. Scheffrahn
- Fort Lauderdale Research and Education Center, University of Florida, Davie, Florida, USA
| | - Andreas Brune
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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Patterns of [FeFe] hydrogenase diversity in the gut microbial communities of lignocellulose-feeding higher termites. Appl Environ Microbiol 2012; 78:5368-74. [PMID: 22636002 DOI: 10.1128/aem.08008-11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydrogen is the central free intermediate in the degradation of wood by termite gut microbes and can reach concentrations exceeding those measured for any other biological system. Degenerate primers targeting the largest family of [FeFe] hydrogenases observed in a termite gut metagenome have been used to explore the evolution and representation of these enzymes in termites. Sequences were cloned from the guts of the higher termites Amitermes sp. strain Cost010, Amitermes sp. strain JT2, Gnathamitermes sp. strain JT5, Microcerotermes sp. strain Cost008, Nasutitermes sp. strain Cost003, and Rhyncotermes sp. strain Cost004. Each gut sample harbored a more rich and evenly distributed population of hydrogenase sequences than observed previously in the guts of lower termites and Cryptocercus punctulatus. This accentuates the physiological importance of hydrogen for higher termite gut ecosystems and may reflect an increased metabolic burden, or metabolic opportunity, created by a lack of gut protozoa. The sequences were phylogenetically distinct from previously sequenced [FeFe] hydrogenases. Phylogenetic and UniFrac comparisons revealed congruence between host phylogeny and hydrogenase sequence library clustering patterns. This may reflect the combined influences of the stable intimate relationship of gut microbes with their host and environmental alterations in the gut that have occurred over the course of termite evolution. These results accentuate the physiological importance of hydrogen to termite gut ecosystems.
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Ballor NR, Leadbetter JR. Analysis of extensive [FeFe] hydrogenase gene diversity within the gut microbiota of insects representing five families of Dictyoptera. MICROBIAL ECOLOGY 2012; 63:586-595. [PMID: 21935609 DOI: 10.1007/s00248-011-9941-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 09/04/2011] [Indexed: 05/31/2023]
Abstract
We have designed and utilized degenerate primers in the phylogenetic analysis of [FeFe] hydrogenase gene diversity in the gut ecosystems of roaches and lower termites. H(2) is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations in some species exceeding those measured for any other biological system. The primers designed target with specificity the largest group of enzymatic H domain proteins previously identified in a termite gut metagenome. "Family 3" hydrogenase sequences were amplified from the guts of lower termites, Incisitermes minor, Zootermopsis nevadensis, and Reticulitermes hesperus, and two roaches, Cryptocercus punctulatus and Periplaneta americana. Subsequent analyses revealed that all termite and Cryptocercus sequences were phylogenetically distinct from non-termite-associated hydrogenases available from public databases. The abundance of unique sequence operational taxonomic units (as many as 21 from each species) underscores the previously demonstrated physiological importance of H(2) to the gut ecosystems of these wood-feeding insects. The diversity of sequences observed might be reflective of multiple niches that the enzymes have been evolved to accommodate. Sequences cloned from Cryptocercus and the lower termite samples, all of which are wood feeding insects, clustered closely with one another in phylogenetic analyses to the exclusion of alleles from P. americana, an omnivorous cockroach, also cloned during this study. We present primers targeting a family of termite gut [FeFe] hydrogenases and provide results that are consistent with a pivotal role for hydrogen in the termite gut ecosystem and point toward unique evolutionary adaptations to the gut ecosystem.
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Affiliation(s)
- Nicholas R Ballor
- Biochemistry and Molecular Biophysics, California Institute of Technology, M/C 138-78, Pasadena, CA 91125, USA
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The bacterial community in the gut of the Cockroach Shelfordella lateralis reflects the close evolutionary relatedness of cockroaches and termites. Appl Environ Microbiol 2012; 78:2758-67. [PMID: 22327579 DOI: 10.1128/aem.07788-11] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Termites and cockroaches are closely related, with molecular phylogenetic analyses even placing termites within the radiation of cockroaches. The intestinal tract of wood-feeding termites harbors a remarkably diverse microbial community that is essential for the digestion of lignocellulose. However, surprisingly little is known about the gut microbiota of their closest relatives, the omnivorous cockroaches. Here, we present a combined characterization of physiological parameters, metabolic activities, and bacterial microbiota in the gut of Shelfordella lateralis, a representative of the cockroach family Blattidae, the sister group of termites. We compared the bacterial communities within each gut compartment using terminal-restriction fragment length polymorphism (T-RFLP) analysis and made a 16S rRNA gene clone library of the microbiota in the colon-the dilated part of the hindgut with the highest density and diversity of bacteria. The colonic community was dominated by members of the Bacteroidetes, Firmicutes (mainly Clostridia), and some Deltaproteobacteria. Spirochaetes and Fibrobacteres, which are abundant members of termite gut communities, were conspicuously absent. Nevertheless, detailed phylogenetic analysis revealed that many of the clones from the cockroach colon clustered with sequences previously obtained from the termite gut, which indicated that the composition of the bacterial community reflects at least in part the phylogeny of the host.
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Ballor NR, Paulsen I, Leadbetter JR. Genomic analysis reveals multiple [FeFe] hydrogenases and hydrogen sensors encoded by treponemes from the H(2)-rich termite gut. MICROBIAL ECOLOGY 2012; 63:282-294. [PMID: 21811792 DOI: 10.1007/s00248-011-9922-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 07/18/2011] [Indexed: 05/31/2023]
Abstract
We have completed a bioinformatic analysis of the hydrogenases encoded in the genomes of three termite gut treponeme isolates: hydrogenotrophic, homoacetogenic Treponema primitia strains ZAS-1 and ZAS-2, and the hydrogen-producing, sugar-fermenting Treponema azotonutricium ZAS-9. H(2) is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations in some species exceeding those measured for any other biological system. The spirochetes encoded 4, 8, and 5 [FeFe] hydrogenase-like proteins, identified by their H domains, respectively, but no other recognizable hydrogenases. The [FeFe] hydrogenases represented many sequence families previously proposed in an analysis of termite gut metagenomic data. Each strain encoded both putative [FeFe] hydrogenase enzymes and evolutionarily related hydrogen sensor/transducer proteins likely involved in phosphorelay or methylation pathways, and possibly even chemotaxis. A new family of [FeFe] hydrogenases (FDH-Linked) is proposed that may form a multimeric complex with formate dehydrogenase to provide reducing equivalents for reductive acetogenesis in T. primitia. The many and diverse [FeFe] hydrogenase-like proteins encoded within the sequenced genomes of the termite gut treponemes has enabled the discovery of a putative new class of [FeFe] hydrogenase proteins potentially involved in acetogenesis and furthered present understanding of many families, including sensory, of H domain proteins beyond what was possible through the use of fragmentary termite gut metagenome sequence data alone, from which they were initially defined.
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Affiliation(s)
- Nicholas R Ballor
- Biochemistry & Molecular Biophysics, California Institute of Technology, Pasadena, CA 91125, USA
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Nguyen HD, Cao B, Mishra B, Boyanov MI, Kemner KM, Fredrickson JK, Beyenal H. Microscale geochemical gradients in Hanford 300 Area sediment biofilms and influence of uranium. WATER RESEARCH 2012; 46:227-234. [PMID: 22078229 DOI: 10.1016/j.watres.2011.10.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/13/2011] [Accepted: 10/25/2011] [Indexed: 05/31/2023]
Abstract
The presence and importance of microenvironments in the subsurface at contaminated sites were suggested by previous geochemical studies. However, no direct quantitative characterization of the geochemical microenvironments had been reported. We quantitatively characterized microscale geochemical gradients (dissolved oxygen (DO), H(2), pH, and redox potential) in Hanford 300A subsurface sediment biofilms. Our results revealed significant differences in geochemical parameters across the sediment biofilm/water interface in the presence and absence of U(VI) under oxic and anoxic conditions. While the pH was relatively constant within the sediment biofilm, the redox potential and the DO and H(2) concentrations were heterogeneous at the microscale (<500-1000 μm). We found microenvironments with high DO levels (DO hotspots) when the sediment biofilm was exposed to U(VI). On the other hand, we found hotspots (high concentrations) of H(2) under anoxic conditions both in the presence and in the absence of U(VI). The presence of anoxic microenvironments inside the sediment biofilms suggests that U(VI) reduction proceeds under bulk oxic conditions. To test this, we operated our biofilm reactor under air-saturated conditions in the presence of U(VI) and characterized U speciation in the sediment biofilm. U L(III)-edge X-ray absorption spectroscopy (XANES and EXAFS) showed that 80-85% of the U was in the U(IV) valence state.
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Affiliation(s)
- Hung Duc Nguyen
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
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Bacteroidales ectosymbionts of gut flagellates shape the nitrogen-fixing community in dry-wood termites. ISME JOURNAL 2011; 6:1302-13. [PMID: 22189498 DOI: 10.1038/ismej.2011.194] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although it is well documented that the lack of nitrogen in the diet of wood-feeding termites is compensated by the nitrogen-fixing capacity of their gut microbiota, the bacteria responsible for this activity are largely unknown. Here, we analyzed the diversity and expression of nitrogenase genes (homologs of nifH) in four species of dry-wood termites (Kalotermitidae), which thrive on a particularly nitrogen-poor resource. Although each species harbored a highly diverse suite of termite-specific homologs in their microliter-sized hindgut, only a core set related to nifH genes of Treponema and Azoarcus spp., 'Azobacteroides pseudotrichonymphae', the first member of the Bacteroidales identified as a diazotroph, and termite-gut-specific anfH genes of hitherto unknown origin were preferentially expressed. Transcription patterns corroborated that the populations of active diazotrophs differ fundamentally between termite genera. Capillary-picked suspensions of the flagellates Devescovina arta and Snyderella tabogae revealed that their bacterial ectosymbionts each possess two paralogs of nifH, which apparently have been acquired consecutively during evolution of Bacteroidales, but only one of them (anfH) is actively expressed. Transcription patterns correlated neither with the molybdenum content of the diet nor with intestinal hydrogen concentrations, measured with microsensors. We propose that the nitrogen-fixing community in different dry-wood termites is shaped by the symbionts of their specific flagellate populations. Our findings suggest that the diazotrophic nature of 'Armantifilum devescovinae' has an important role in the nitrogen metabolism of dry-wood termites and is the driving force of co-evolution with its flagellate host.
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Matson EG, Gora KG, Leadbetter JR. Anaerobic carbon monoxide dehydrogenase diversity in the homoacetogenic hindgut microbial communities of lower termites and the wood roach. PLoS One 2011; 6:e19316. [PMID: 21541298 PMCID: PMC3082573 DOI: 10.1371/journal.pone.0019316] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 03/30/2011] [Indexed: 11/18/2022] Open
Abstract
Anaerobic carbon monoxide dehydrogenase (CODH) is a key enzyme in the Wood-Ljungdahl (acetyl-CoA) pathway for acetogenesis performed by homoacetogenic bacteria. Acetate generated by gut bacteria via the acetyl-CoA pathway provides considerable nutrition to wood-feeding dictyopteran insects making CODH important to the obligate mutualism occurring between termites and their hindgut microbiota. To investigate CODH diversity in insect gut communities, we developed the first degenerate primers designed to amplify cooS genes, which encode the catalytic (β) subunit of anaerobic CODH enzyme complexes. These primers target over 68 million combinations of potential forward and reverse cooS primer-binding sequences. We used the primers to identify cooS genes in bacterial isolates from the hindgut of a phylogenetically lower termite and to sample cooS diversity present in a variety of insect hindgut microbial communities including those of three phylogenetically-lower termites, Zootermopsis nevadensis, Reticulitermes hesperus, and Incisitermes minor, a wood-feeding cockroach, Cryptocercus punctulatus, and an omnivorous cockroach, Periplaneta americana. In total, we sequenced and analyzed 151 different cooS genes. These genes encode proteins that group within one of three highly divergent CODH phylogenetic clades. Each insect gut community contained CODH variants from all three of these clades. The patterns of CODH diversity in these communities likely reflect differences in enzyme or physiological function, and suggest that a diversity of microbial species participate in homoacetogenesis in these communities.
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Affiliation(s)
- Eric G Matson
- Ronald and Maxine Linde Center for Global Environmental Science, California Institute of Technology, Pasadena, California, United States of America.
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Hongoh Y. Toward the functional analysis of uncultivable, symbiotic microorganisms in the termite gut. Cell Mol Life Sci 2011; 68:1311-25. [PMID: 21365277 PMCID: PMC11114660 DOI: 10.1007/s00018-011-0648-z] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 02/15/2011] [Accepted: 02/15/2011] [Indexed: 11/29/2022]
Abstract
Termites thrive on dead plant matters with the aid of microorganisms resident in their gut. The gut microbiota comprises protists (single-celled eukaryotes), bacteria, and archaea, most of which are unique to the termite gut ecosystem. Although this symbiosis has long been intriguing researchers of both basic and applied sciences, its detailed mechanism remains unclear due to the enormous complexity and the unculturability of the microbiota. In the effort to overcome the difficulty, recent advances in omics, such as metagenomics, metatranscriptomics, and metaproteomics have gradually unveiled the black box of this symbiotic system. Genomics targeting a single species of the unculturable microbial members has also provided a great progress in the understanding of the symbiotic interrelationships among the gut microorganisms. In this review, the symbiotic system organized by wood-feeding termites and their gut microorganisms is outlined, focusing on the recent achievement in omics studies of this multilayered symbiotic system.
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Affiliation(s)
- Yuichi Hongoh
- Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan.
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Zhang X, Matson EG, Leadbetter JR. Genes for selenium dependent and independent formate dehydrogenase in the gut microbial communities of three lower, wood-feeding termites and a wood-feeding roach. Environ Microbiol 2010; 13:307-23. [PMID: 20819103 DOI: 10.1111/j.1462-2920.2010.02330.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bacterial Wood-Ljungdahl pathway for CO(2)-reductive acetogenesis is important for the nutritional mutualism occurring between wood-feeding insects and their hindgut microbiota. A key step in this pathway is the reduction of CO(2) to formate, catalysed by the enzyme formate dehydrogenase (FDH). Putative selenocysteine- (Sec) and cysteine- (Cys) containing paralogues of hydrogenase-linked FDH (FDH(H)) have been identified in the termite gut acetogenic spirochete, Treponema primitia, but knowledge of their relevance in the termite gut environment remains limited. In this study, we designed degenerate PCR primers for FDH(H) genes (fdhF) and assessed fdhF diversity in insect gut bacterial isolates and the gut microbial communities of termites and cockroaches. The insects examined herein represent three wood-feeding termite families, Termopsidae, Kalotermitidae and Rhinotermitidae (phylogenetically 'lower' termite taxa); the wood-feeding roach family Cryptocercidae (the sister taxon to termites); and the omnivorous roach family Blattidae. Sec and Cys FDH(H) variants were identified in every wood-feeding insect but not the omnivorous roach. Of 68 novel alleles obtained from inventories, 66 affiliated phylogenetically with enzymes from T. primitia. These formed two subclades (37 and 29 phylotypes) almost completely comprised of Sec-containing and Cys-containing enzymes respectively. A gut cDNA inventory showed transcription of both variants in the termite Zootermopsis nevadensis (family Termopsidae). The gene patterns suggest that FDH(H) enzymes are important for the CO(2)-reductive metabolism of uncultured acetogenic treponemes and imply that the availability of selenium, a trace element, shaped microbial gene content in the last common ancestor of dictyopteran, wood-feeding insects, and continues to shape it to this day.
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Affiliation(s)
- Xinning Zhang
- Ronald and Maxine Linde Center for Global Environmental Science, Mailcode 138-78, California Institute of Technology, Pasadena, CA 91125, USA
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Matson EG, Zhang X, Leadbetter JR. Selenium controls transcription of paralogous formate dehydrogenase genes in the termite gut acetogen, Treponema primitia. Environ Microbiol 2010; 12:2245-58. [PMID: 21966917 DOI: 10.1111/j.1462-2920.2010.02188.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The termite gut spirochete, Treponema primitia, is a CO(2)-reductive acetogen that is phylogenetically distinct from other distantly related and more extensively studied acetogens such as Moorella thermoacetica. Research on T. primitia has revealed details about the role of spirochetes in CO(2)-reductive acetogenesis, a process important to the mutualism occurring between termites and their gut microbial communities. Here, a locus of the T. primitia genome containing Wood-Ljungdahl pathway genes for CO(2)-reductive acetogenesis was sequenced. This locus contained methyl-branch genes of the pathway (i.e. for the reduction of CO(2) to the level of methyl-tetrahydrofolate) including paralogous genes for cysteine and selenocysteine (Sec) variants of formate dehydrogenase (FDH) and genes for Sec incorporation. The FDH variants affiliated phylogenetically with hydrogenase-linked FDH enzymes, suggesting that T. primitia FDH enzymes utilize electrons derived directly from molecular H(2). Sub-nanomolar concentrations of selenium decreased transcript levels of the cysteine variant FDH gene. Selenium concentration did not markedly influence the level of mRNA upstream of the Sec-codon in the Sec variant FDH; however, the level of transcript extending downstream of the Sec-codon increased incrementally with increasing selenium concentrations. The features and regulation of these FDH genes are an indication that T. primitia may experience dynamic selenium availability in its H(2)-rich gut environment.
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Affiliation(s)
- Eric G Matson
- Ronald and Maxine Linde Center for Global Environmental Science, Mailcode 138-78, California Institute of Technology, Pasadena, CA 91125, USA
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Termite Gut Flagellates and Their Methanogenic and Eubacterial Symbionts. (ENDO)SYMBIOTIC METHANOGENIC ARCHAEA 2010. [DOI: 10.1007/978-3-642-13615-3_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Brune A. Methanogens in the Digestive Tract of Termites. (ENDO)SYMBIOTIC METHANOGENIC ARCHAEA 2010. [DOI: 10.1007/978-3-642-13615-3_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Liu Y, Whitman WB. Metabolic, phylogenetic, and ecological diversity of the methanogenic archaea. Ann N Y Acad Sci 2008; 1125:171-89. [PMID: 18378594 DOI: 10.1196/annals.1419.019] [Citation(s) in RCA: 626] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Although of limited metabolic diversity, methanogenic archaea or methanogens possess great phylogenetic and ecological diversity. Only three types of methanogenic pathways are known: CO(2)-reduction, methyl-group reduction, and the aceticlastic reaction. Cultured methanogens are grouped into five orders based upon their phylogeny and phenotypic properties. In addition, uncultured methanogens that may represent new orders are present in many environments. The ecology of methanogens highlights their complex interactions with other anaerobes and the physical and chemical factors controlling their function.
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Affiliation(s)
- Yuchen Liu
- Department of Microbiology, University of Georgia, 541 Biological Sciences Building, Athens, GA 30605, USA
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