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Verma A, Bhagchandani T, Rai A, Nikita, Sardarni UK, Bhavesh NS, Gulati S, Malik R, Tandon R. Short-Chain Fatty Acid (SCFA) as a Connecting Link between Microbiota and Gut-Lung Axis-A Potential Therapeutic Intervention to Improve Lung Health. ACS OMEGA 2024; 9:14648-14671. [PMID: 38585101 PMCID: PMC10993281 DOI: 10.1021/acsomega.3c05846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 04/09/2024]
Abstract
The microbiome is an integral part of the human gut, and it plays a crucial role in the development of the immune system and homeostasis. Apart from the gut microbiome, the airway microbial community also forms a distinct and crucial part of the human microbiota. Furthermore, several studies indicate the existence of communication between the gut microbiome and their metabolites with the lung airways, called "gut-lung axis". Perturbations in gut microbiota composition, termed dysbiosis, can have acute and chronic effects on the pathophysiology of lung diseases. Microbes and their metabolites in lung stimulate various innate immune pathways, which modulate the expression of the inflammatory genes in pulmonary leukocytes. For instance, gut microbiota-derived metabolites such as short-chain fatty acids can suppress lung inflammation through the activation of G protein-coupled receptors (free fatty acid receptors) and can also inhibit histone deacetylase, which in turn influences the severity of acute and chronic respiratory diseases. Thus, modulation of the gut microbiome composition through probiotic/prebiotic usage and fecal microbiota transplantation can lead to alterations in lung homeostasis and immunity. The resulting manipulation of immune cells function through microbiota and their key metabolites paves the way for the development of novel therapeutic strategies in improving the lung health of individuals affected with various lung diseases including SARS-CoV-2. This review will shed light upon the mechanistic aspect of immune system programming through gut and lung microbiota and exploration of the relationship between gut-lung microbiome and also highlight the therapeutic potential of gut microbiota-derived metabolites in the management of respiratory diseases.
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Affiliation(s)
- Anjali Verma
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Tannu Bhagchandani
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ankita Rai
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Nikita
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Urvinder Kaur Sardarni
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Neel Sarovar Bhavesh
- Transcription
Regulation Group, International Centre for
Genetic Engineering and Biotechnology (ICGEB), New Delhi 110067, India
| | - Sameer Gulati
- Department
of Medicine, Lady Hardinge Medical College
(LHMC), New Delhi 110058, India
| | - Rupali Malik
- Department
of Medicine, Vardhman Mahavir Medical College
and Safdarjung Hospital, New Delhi 110029, India
| | - Ravi Tandon
- Laboratory
of AIDS Research and Immunology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
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Cerna-Vargas JP, Gumerov VM, Krell T, Zhulin IB. Amine-recognizing domain in diverse receptors from bacteria and archaea evolved from the universal amino acid sensor. Proc Natl Acad Sci U S A 2023; 120:e2305837120. [PMID: 37819981 PMCID: PMC10589655 DOI: 10.1073/pnas.2305837120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 09/09/2023] [Indexed: 10/13/2023] Open
Abstract
Bacteria possess various receptors that sense different signals and transmit information to enable an optimal adaptation to the environment. A major limitation in microbiology is the lack of information on the signal molecules that activate receptors. Signals recognized by sensor domains are poorly reflected in overall sequence identity, and therefore, the identification of signals from the amino acid sequence of the sensor alone presents a challenge. Biogenic amines are of great physiological importance for microorganisms and humans. They serve as substrates for aerobic and anaerobic growth and play a role of neurotransmitters and osmoprotectants. Here, we report the identification of a sequence motif that is specific for amine-sensing sensor domains that belong to the Cache superfamily of the most abundant extracellular sensors in prokaryotes. We identified approximately 13,000 sensor histidine kinases, chemoreceptors, receptors involved in second messenger homeostasis and Ser/Thr phosphatases from 8,000 bacterial and archaeal species that contain the amine-recognizing motif. The screening of compound libraries and microcalorimetric titrations of selected sensor domains confirmed their ability to specifically bind biogenic amines. Mutants in the amine-binding motif or domains that contain a single mismatch in the binding motif had either no or a largely reduced affinity for amines. We demonstrate that the amine-recognizing domain originated from the universal amino acid-sensing Cache domain, thus providing insight into receptor evolution. Our approach enables precise "wet"-lab experiments to define the function of regulatory systems and therefore holds a strong promise to enable the identification of signals stimulating numerous receptors.
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Affiliation(s)
- Jean Paul Cerna-Vargas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada18008, Spain
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria/Consejo Superior de Investigaciones Científicas, Parque Científico y Tecnológico de la Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid28223, Spain
| | - Vadim M. Gumerov
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH43210
| | - Tino Krell
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada18008, Spain
| | - Igor B. Zhulin
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH43210
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Cerna-Vargas JP, Gumerov VM, Krell T, Zhulin IB. Amine recognizing domain in diverse receptors from bacteria and archaea evolved from the universal amino acid sensor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.06.535858. [PMID: 37066253 PMCID: PMC10104139 DOI: 10.1101/2023.04.06.535858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Bacteria contain many different receptor families that sense different signals permitting an optimal adaptation to the environment. A major limitation in microbiology is the lack of information on the signal molecules that activate receptors. Due to a significant sequence divergence, the signal recognized by sensor domains is only poorly reflected in overall sequence identity. Biogenic amines are of central physiological relevance for microorganisms and serve for example as substrates for aerobic and anaerobic growth, neurotransmitters or osmoprotectants. Based on protein structural information and sequence analysis, we report here the identification of a sequence motif that is specific for amine-sensing dCache sensor domains (dCache_1AM). These domains were identified in more than 13,000 proteins from 8,000 bacterial and archaeal species. dCache_1AM containing receptors were identified in all major receptor families including sensor kinases, chemoreceptors, receptors involved in second messenger homeostasis and Ser/Thr phosphatases. The screening of compound libraries and microcalorimetric titrations of selected dCache_1AM domains confirmed their capacity to specifically bind amines. Mutants in the amine binding motif or domains that contain a single mismatch in the binding motif, had either no or a largely reduced affinity for amines, illustrating the specificity of this motif. We demonstrate that the dCache_1AM domain has evolved from the universal amino acid sensing domain, providing novel insight into receptor evolution. Our approach enables precise "wet"-lab experiments to define the function of regulatory systems and thus holds a strong promise to address an important bottleneck in microbiology: the identification of signals that stimulate numerous receptors.
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Affiliation(s)
- Jean Paul Cerna-Vargas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
- Centro de Biotecnología y Genómica de Plantas CBGP, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria/CSIC, Parque Científico y Tecnológico de la UPM, Pozuelo de Alarcón, Madrid, Spain
| | - Vadim M. Gumerov
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Tino Krell
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Igor B. Zhulin
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210, USA
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Świątkiewicz M, Zimniewska M, Różańska W, Gryszczyńska A, Kołodziej J, Młocek W, Czech A. Assessment of flax and hemp fibres in terms of their impact on the growth performance and health status of weaned piglets. Animal 2022; 16:100677. [PMID: 36481350 DOI: 10.1016/j.animal.2022.100677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/13/2022] Open
Abstract
Weaning is a critical phase in intensive piglet production marked by the frequent occurrence of digestive disorders posing health and economic burden. To stave off such weaning-related problems, antibiotics and supplements containing high levels of ZnO are often used. In this study, we investigated whether natural fibres obtained from two plants known for their dietary fibre profile and antioxidant properties: flax (Linum usitatissimum L.) and hemp (Cannabis sativa L.), can serve as a health-promoting diet supplement. The study was conducted on a total of 191 Polish Large White piglets from 18 L, from their birth to 56 days of age. Piglets were divided by litters into six groups: W1.5, F1.5, H1.5, W2.0, F2.0, and H2.0. Groups W1.5, F1.5, and H1.5 received feed supplemented with 1.5% fibre from wood cellulose (W), flax (F), and hemp (H), respectively, while groups W2.0, F2.0, and H2.0 received feed with a higher 2.0% content of the same fibres. Flax and hemp fibres were characterised by a complex composition, antioxidant properties due to the presence of phenolic acids, and low risk of mycotoxin contamination. Flax fibre resulted in best weight gains and feed conversion ratio (P ≤ 0.05) of piglets, while hemp fibre had higher positive effect on antioxidant status (P ≤ 0.05) compared to the other two fibre additives. Neither flax nor hemp fibres had any adverse effect on the haematological and biochemical blood parameters. Piglets receiving a diet with 1.5% added fibre showed better growth performance, while diet supplementation with 2% fibre had a beneficial effect on the content of butyric acid in the small intestinal chyme (P ≤ 0.05). The results suggested that both flax and hemp fibres can be innovative feed additives for weaned piglets. However, further studies should be conducted in commercial farms, as the effects of dietary fibre could vary in more challenging environmental conditions.
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Affiliation(s)
- M Świątkiewicz
- Department of Animal Nutrition and Feed Science, National Research Institute of Animal Production, ul. Krakowska 1, 32-083 Balice, Poland.
| | - M Zimniewska
- Department of Innovative Textile Technologies, Institute of Natural Fibres and Medicinal Plants National Research Institute, ul. Wojska Polskiego 71b, 60-630 Poznań, Poland
| | - W Różańska
- Department of Innovative Textile Technologies, Institute of Natural Fibres and Medicinal Plants National Research Institute, ul. Wojska Polskiego 71b, 60-630 Poznań, Poland
| | - A Gryszczyńska
- Department of Pharmacology and Phytochemistry, Institute of Natural Fibres and Medicinal Plants National Research Institute, ul. Wojska Polskiego 71b, 60-630 Poznań, Poland
| | - J Kołodziej
- Department of Innovative Textile Technologies, Institute of Natural Fibres and Medicinal Plants National Research Institute, ul. Wojska Polskiego 71b, 60-630 Poznań, Poland
| | - W Młocek
- Department of Applied Mathematics, University of Agriculture in Krakow, ul. Balicka 253c, 30-198 Krakow, Poland
| | - A Czech
- Department of Biochemistry and Toxicology, University of Life Sciences in Lublin, ul. Akademicka 13, 20-950 Lublin, Poland
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Wijdeveld M, Nieuwdorp M, IJzerman R. The interaction between microbiome and host central nervous system: the gut-brain axis as a potential new therapeutic target in the treatment of obesity and cardiometabolic disease. Expert Opin Ther Targets 2020; 24:639-653. [PMID: 32441559 DOI: 10.1080/14728222.2020.1761958] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The role of the intestinal microbiota in host cardiometabolic health and disease has gained significant attention over recent decades. Previous studies have shown effects on metabolic health through gut microbiota modulation; this suggests diverse interaction pathways that constitute the communication between gut microbiota and host central nervous system, the so-called gut-brain axis. AREAS COVERED This article provides an overview of the various mechanisms that may mediate the gut-brain axis. It places an emphasis on cardiometabolic health, including effects of short-chain fatty acids (SCFA), alterations in neurotransmitters and gut peptides and microbial effects on chronic inflammation and immune function. Moreover, this paper sheds light on whether these mechanisms afford therapeutic targets to promote metabolic health. To this end, a PubMed search with the terms 'gut microbiota,' 'obesity' and 'insulin sensitivity' was performed. EXPERT OPINION Many properties of the human gut microbiome are associated with the central regulation of appetite and metabolic status. Some of these relationships are causal and there are positive effects from certain intervention methods. Microbial manipulation may offer a means to prevent or treat obesity and associated co-morbidities. However, to establish direct causal relations between altered gut microbiota and metabolic disease, clinical intervention studies are necessary.
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Affiliation(s)
- Madelief Wijdeveld
- Department of Internal and Vascular Medicine, Amsterdam University Medical Centers , Amsterdam, The Netherlands
| | - Max Nieuwdorp
- Department of Internal and Vascular Medicine, Amsterdam University Medical Centers , Amsterdam, The Netherlands
| | - Richard IJzerman
- Department of Endocrinology, Amsterdam University Medical Centers , Amsterdam, The Netherlands
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Paulo LM, Hidayat MR, Moretti G, Stams AJM, Sousa DZ. Effect of nickel, cobalt, and iron on methanogenesis from methanol and cometabolic conversion of 1,2-dichloroethene by Methanosarcina barkeri. Biotechnol Appl Biochem 2020; 67:744-750. [PMID: 32282086 PMCID: PMC7687089 DOI: 10.1002/bab.1925] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 03/17/2020] [Indexed: 01/28/2023]
Abstract
Methanogens are responsible for the last step in anaerobic digestion (AD), in which methane (a biofuel) is produced. Some methanogens can cometabolize chlorinated pollutants, contributing for their removal during AD. Methanogenic cofactors involved in cometabolic reductive dechlorination, such as F430 and cobalamin, contain metal ions (nickel, cobalt, iron) in their structure. We hypothesized that the supplementation of trace metals could improve methane production and the cometabolic dechlorination of 1,2‐dichloroethene (DCE) by pure cultures of Methanosarcina barkeri. Nickel, cobalt, and iron were added to cultures of M. barkeri growing on methanol and methanol plus DCE. Metal amendment improved DCE dechlorination to vinyl chloride (VC): assays with 20 µM of Fe3+ showed the highest final concentration of VC (5× higher than in controls without Fe3+), but also in assays with 5.5 µM of Co2+ and 5 µM of Ni2+ VC formation was improved (3.5–4× higher than in controls without the respective metals). Dosing of metals could be useful to improve anaerobic removal of chlorinated compounds, and more importantly decrease the detrimental effect of DCE on methane production in anaerobic digesters.
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Affiliation(s)
- Lara M Paulo
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Mohamad R Hidayat
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Giulio Moretti
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands.,Laboratory of Microbiology, MESVA Department, University of L'Aquila, Via Vetoio Coppito (AQ), Italy
| | - Alfons J M Stams
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
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Mayer F, Enzmann F, Lopez AM, Holtmann D. Performance of different methanogenic species for the microbial electrosynthesis of methane from carbon dioxide. BIORESOURCE TECHNOLOGY 2019; 289:121706. [PMID: 31279320 DOI: 10.1016/j.biortech.2019.121706] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/21/2019] [Accepted: 06/26/2019] [Indexed: 06/09/2023]
Abstract
Microbial electrosynthesis (MES) is a promising technology to convert CO2 and electricity into the biofuel methane using methanogens. Until now, most investigations on electro-methanogenesis are "proof-of-principle" studies. In this paper, different strains were quantitatively compared in regard to final methane concentration, yields based on CO2-conversion, productivities as well as Coulombic efficiencies in order to identify suitable organisms for MES. Methanococcus vannielii, Methanococcus maripaludis, Methanolacinia petrolearia, Methanobacterium congolense, and Methanoculleus submarinus were able to produce methane via MES at -700 mV vs. standard hydrogen electrode (SHE). Beside methane also biological H2 production was detected during MES, which might be due to the involvement of hydrogenases. A direct electron transfer pathway is most likely. Obviously, M. maripaludis is the most resource efficient methane producer in microbial electrosynthesis regarding the methane productivity (8.81 ± 0.51 mmol m-2 d-1) and the Coulombic efficiency (58.9 ± 0.8%).
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Affiliation(s)
- Florian Mayer
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany
| | - Franziska Enzmann
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany
| | | | - Dirk Holtmann
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany.
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8
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Karabey B, Daglioglu ST, Azbar N, Ozdemir G. Bacterial and archeal dynamics of a labscale HYBRID gas fermentation bioreactor fed with CO 2 and H 2. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2019; 54:1348-1355. [PMID: 31446840 DOI: 10.1080/10934529.2019.1649589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/26/2019] [Accepted: 06/28/2019] [Indexed: 06/10/2023]
Abstract
16s rDNA-based methods were used in order to identify the dynamics of microbial profiles in a HYBRID gas fermentation bio-methanization reactor. The effects of various H2 and CO2 ratios on microbial community were investigated. The HYBRID gas fermentation reactor was composed of granular anaerobic seed and the system fed with only H2 and CO2 gases. No additional organic material and trace element was fed during the throughout the experiments; thus, the microbial diversity was directly related to production of methane. The dynamics of the microbial communities were investigated with DGGE and real-time PCR analysis. The results showed that Methanobacteriales members were more dominated than Methanosarcinales and Methanomicrobiales members in the system. DGGE results indicated that Methanosaeta concilii, Methanoculleus sp., Methanosphaerula palustris, Methanofollis formosanus, Methanolinea sp., and Methanobacterium palustre were the most prominent methanogens depending on different H2/CO2 ratios. DGGE profiles suggested that hydrogenotrophic and acetoclastic species were responsible for the production of methane. The survival of syntrophic bacteria and acetoclastic methanogens was attributed to their utilization of organic materials provided by lysis. To the best of our knowledge, this is the first microbial profile detection study in a hybrid bioreactor system operated with only pure hydrogen and carbon dioxide.
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Affiliation(s)
- Burcin Karabey
- Department of Biology, Faculty of Science, Ege University , Izmir , Turkey
- Department of Molecular Biology and Genetics, Faculty of Arts and Science, Ordu University , Ordu , Turkey
| | | | - Nuri Azbar
- Department of Bioengineering, Faculty of Engineering, Ege University , Izmir , Turkey
| | - Guven Ozdemir
- Department of Biology, Faculty of Science, Ege University , Izmir , Turkey
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Lackner N, Hintersonnleitner A, Wagner AO, Illmer P. Hydrogenotrophic Methanogenesis and Autotrophic Growth of Methanosarcina thermophila. ARCHAEA (VANCOUVER, B.C.) 2018; 2018:4712608. [PMID: 30123085 PMCID: PMC6079545 DOI: 10.1155/2018/4712608] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/03/2018] [Accepted: 06/13/2018] [Indexed: 11/24/2022]
Abstract
Although Methanosarcinales are versatile concerning their methanogenic substrates, the ability of Methanosarcina thermophila to use carbon dioxide (CO2) for catabolic and anabolic metabolism was not proven until now. Here, we show that M. thermophila used CO2 to perform hydrogenotrophic methanogenesis in the presence as well as in the absence of methanol. During incubation with hydrogen, the methanogen utilized the substrates methanol and CO2 consecutively, resulting in a biphasic methane production. Growth exclusively from CO2 occurred slowly but reproducibly with concomitant production of biomass, verified by DNA quantification. Besides verification through multiple transfers into fresh medium, the identity of the culture was confirmed by 16s RNA sequencing, and the incorporation of carbon atoms from 13CO2 into 13CH4 molecules was measured to validate the obtained data. New insights into the physiology of M. thermophila can serve as reference for genomic analyses to link genes with metabolic features in uncultured organisms.
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Affiliation(s)
- Nina Lackner
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020 Innsbruck, Austria
| | - Anna Hintersonnleitner
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020 Innsbruck, Austria
| | - Andreas Otto Wagner
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020 Innsbruck, Austria
| | - Paul Illmer
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020 Innsbruck, Austria
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Xiang Y, Liu G, Zhang R, Lu Y, Luo H. High-efficient acetate production from carbon dioxide using a bioanode microbial electrosynthesis system with bipolar membrane. BIORESOURCE TECHNOLOGY 2017; 233:227-235. [PMID: 28282609 DOI: 10.1016/j.biortech.2017.02.104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/20/2017] [Accepted: 02/22/2017] [Indexed: 06/06/2023]
Abstract
The aim of this study was to develop an efficient bioanode microbial electrosynthesis system (MES) to convert carbon dioxide into acetate using bioenergy from the wastewater. The bioanode MESs were constructed using proton exchange membrane (PEM) and bipolar membrane (BPM) as separator, respectively, and operated under different voltages (i.e., 0.8, 1.0, 1.2, and 1.4V). Since BPM could dissociate H2O into H+ and OH- in situ to buffer the pH change in the chambers, the BPM-MES achieved 238% improvement in cathodic acetate production rate, 45% increase in anodic substrate removal efficiency, and more than five times enhancement in current output, as compared to the PEM-MES. The biomass on the surface of anode and cathode, and the relative abundance of Acetobacterium in the cathode of BPM-MES was higher than that in PEM-MES. Bioanode MES with BPM should be a useful microbial electrosynthesis strategy for acetate production using bioenergy from wastewater treatment.
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Affiliation(s)
- Yinbo Xiang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Guangli Liu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Renduo Zhang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Yaobin Lu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Haiping Luo
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
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11
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Influence of Diet Composition on Cattle Rumen Methanogenesis: A Comparative Metagenomic Analysis in Indian and Exotic Cattle. Indian J Microbiol 2017; 57:226-234. [PMID: 28611501 DOI: 10.1007/s12088-016-0635-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/16/2016] [Indexed: 01/25/2023] Open
Abstract
Comparative metagenomics approach has been used in this study to discriminate colonization of methanogenic population in different breeds of cattle. We compared two Indian cattle breeds (Gir and Kankrej) and two exotic cattle (Holstein and Jersey) breeds. Using a defined dietary plan for selected Indian varieties, the diet dependent shifts in microbial community and abundance of the enzymes associated with methanogenesis were studied. This data has been compared with the available rumen metagenome data from Holstein and Jersey dairy cattle. The abundance of genes for methanogenesis in Holstein and Jersey cattle came from Methanobacteriales order whereas, majority of the enzymes for methanogenesis in Gir and Kankrej cattle came from Methanomicrobiales order. The study suggested that by using slow/less digestible feed, the propionate levels could be controlled in rumen; and in turn, this would also help in further reducing the hydrogenotrophic production of methane. The study proposes that with the designed diet plan the overall methanogenic microbial pool or the individual methanogens could be targeted for development of methane mitigation strategies.
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12
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Basson A, Trotter A, Rodriguez-Palacios A, Cominelli F. Mucosal Interactions between Genetics, Diet, and Microbiome in Inflammatory Bowel Disease. Front Immunol 2016; 7:290. [PMID: 27531998 PMCID: PMC4970383 DOI: 10.3389/fimmu.2016.00290] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/19/2016] [Indexed: 12/12/2022] Open
Abstract
Numerous reviews have discussed gut microbiota composition changes during inflammatory bowel diseases (IBD), particularly Crohn’s disease (CD). However, most studies address the observed effects by focusing on studying the univariate connection between disease and dietary-induced alterations to gut microbiota composition. The possibility that these effects may reflect a number of other interconnected (i.e., pantropic) mechanisms, activated in parallel, particularly concerning various bacterial metabolites, is in the process of being elucidated. Progress seems, however, hampered by various difficult-to-study factors interacting at the mucosal level. Here, we highlight some of such factors that merit consideration, namely: (1) the contribution of host genetics and diet in altering gut microbiome, and in turn, the crosstalk among secondary metabolic pathways; (2) the interdependence between the amount of dietary fat, the fatty acid composition, the effects of timing and route of administration on gut microbiota community, and the impact of microbiota-derived fatty acids; (3) the effect of diet on bile acid composition, and the modulator role of bile acids on the gut microbiota; (4) the impact of endogenous and exogenous intestinal micronutrients and metabolites; and (5) the need to consider food associated toxins and chemicals, which can introduce confounding immune modulating elements (e.g., antioxidant and phytochemicals in oils and proteins). These concepts, which are not mutually exclusive, are herein illustrated paying special emphasis on physiologically inter-related processes.
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Affiliation(s)
- Abigail Basson
- Digestive Health Research Institute, Case Western Reserve University , Cleveland, OH , USA
| | - Ashley Trotter
- Digestive Health Research Institute, Case Western Reserve University, Cleveland, OH, USA; University Hospitals Case Medical Center, Cleveland, OH, USA
| | | | - Fabio Cominelli
- Digestive Health Research Institute, Case Western Reserve University, Cleveland, OH, USA; University Hospitals Case Medical Center, Cleveland, OH, USA
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13
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Colon microbiota fermentation of dietary prebiotics towards short-chain fatty acids and their roles as anti-inflammatory and antitumour agents: A review. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.06.032] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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14
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Mikelsaar M, Sepp E, Štšepetova J, Songisepp E, Mändar R. Biodiversity of Intestinal Lactic Acid Bacteria in the Healthy Population. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 932:1-64. [DOI: 10.1007/5584_2016_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Noah M, Lappé M, Schneider B, Vieth-Hillebrand A, Wilkes H, Kallmeyer J. Tracing biogeochemical and microbial variability over a complete oil sand mining and recultivation process. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 499:297-310. [PMID: 25201817 DOI: 10.1016/j.scitotenv.2014.08.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 07/31/2014] [Accepted: 08/08/2014] [Indexed: 06/03/2023]
Abstract
Recultivation of disturbed oil sand mining areas is an issue of increasing importance. Nevertheless only little is known about the fate of organic matter, cell abundances and microbial community structures during oil sand processing, tailings management and initial soil development on reclamation sites. Thus the focus of this work is on biogeochemical changes of mined oil sands through the entire process chain until its use as substratum for newly developing soils on reclamation sites. Therefore, oil sand, mature fine tailings (MFTs) from tailings ponds and drying cells and tailings sand covered with peat-mineral mix (PMM) as part of land reclamation were analyzed. The sample set was selected to address the question whether changes in the above-mentioned biogeochemical parameters can be related to oil sand processing or biological processes and how these changes influence microbial activities and soil development. GC-MS analyses of oil-derived biomarkers reveal that these compounds remain unaffected by oil sand processing and biological activity. In contrast, changes in polycyclic aromatic hydrocarbon (PAH) abundance and pattern can be observed along the process chain. Especially naphthalenes, phenanthrenes and chrysenes are altered or absent on reclamation sites. Furthermore, root-bearing horizons on reclamation sites exhibit cell abundances at least ten times higher (10(8) to 10(9) cells g(-1)) than in oil sand and MFT samples (10(7) cells g(-1)) and show a higher diversity in their microbial community structure. Nitrate in the pore water and roots derived from the PMM seem to be the most important stimulants for microbial growth. The combined data show that the observed compositional changes are mostly related to biological activity and the addition of exogenous organic components (PMM), whereas oil extraction, tailings dewatering and compaction do not have significant influences on the evaluated compounds. Microbial community composition remains relatively stable through the entire process chain.
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Affiliation(s)
- Mareike Noah
- GFZ German Research Centre for Geosciences, Section 4.3 Organic Geochemistry, Telegrafenberg, 14473 Potsdam, Germany.
| | - Michael Lappé
- University of Potsdam, Institute of Earth and Environmental Science, Geomicrobiology Group, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Beate Schneider
- University of Potsdam, Institute of Earth and Environmental Science, Geomicrobiology Group, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Andrea Vieth-Hillebrand
- GFZ German Research Centre for Geosciences, Section 4.3 Organic Geochemistry, Telegrafenberg, 14473 Potsdam, Germany
| | - Heinz Wilkes
- GFZ German Research Centre for Geosciences, Section 4.3 Organic Geochemistry, Telegrafenberg, 14473 Potsdam, Germany
| | - Jens Kallmeyer
- GFZ German Research Centre for Geosciences, Section 4.5 Geomicrobiology, Telegrafenberg, 14473 Potsdam, Germany
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16
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Tan J, McKenzie C, Potamitis M, Thorburn AN, Mackay CR, Macia L. The role of short-chain fatty acids in health and disease. Adv Immunol 2014; 121:91-119. [PMID: 24388214 DOI: 10.1016/b978-0-12-800100-4.00003-9] [Citation(s) in RCA: 1398] [Impact Index Per Article: 139.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
There is now an abundance of evidence to show that short-chain fatty acids (SCFAs) play an important role in the maintenance of health and the development of disease. SCFAs are a subset of fatty acids that are produced by the gut microbiota during the fermentation of partially and nondigestible polysaccharides. The highest levels of SCFAs are found in the proximal colon, where they are used locally by enterocytes or transported across the gut epithelium into the bloodstream. Two major SCFA signaling mechanisms have been identified, inhibition of histone deacetylases (HDACs) and activation of G-protein-coupled receptors (GPCRs). Since HDACs regulate gene expression, inhibition of HDACs has a vast array of downstream consequences. Our understanding of SCFA-mediated inhibition of HDACs is still in its infancy. GPCRs, particularly GPR43, GPR41, and GPR109A, have been identified as receptors for SCFAs. Studies have implicated a major role for these GPCRs in the regulation of metabolism, inflammation, and disease. SCFAs have been shown to alter chemotaxis and phagocytosis; induce reactive oxygen species (ROS); change cell proliferation and function; have anti-inflammatory, antitumorigenic, and antimicrobial effects; and alter gut integrity. These findings highlight the role of SCFAs as a major player in maintenance of gut and immune homeostasis. Given the vast effects of SCFAs, and that their levels are regulated by diet, they provide a new basis to explain the increased prevalence of inflammatory disease in Westernized countries, as highlighted in this chapter.
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Affiliation(s)
- Jian Tan
- Department of Immunology, Monash University, Clayton, Victoria, Australia
| | - Craig McKenzie
- Department of Immunology, Monash University, Clayton, Victoria, Australia
| | - Maria Potamitis
- Department of Immunology, Monash University, Clayton, Victoria, Australia
| | - Alison N Thorburn
- Department of Immunology, Monash University, Clayton, Victoria, Australia
| | - Charles R Mackay
- Department of Immunology, Monash University, Clayton, Victoria, Australia.
| | - Laurence Macia
- Department of Immunology, Monash University, Clayton, Victoria, Australia.
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17
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Lins P, Schwarzenauer T, Reitschuler C, Wagner AO, Illmer P. Methanogenic potential of formate in thermophilic anaerobic digestion. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2012; 30:1031-40. [PMID: 22588113 DOI: 10.1177/0734242x12445655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In the present study the methanogenic potential of formate (HCOO(-)) during thermophilic anaerobic digestion was investigated. After appropriate conditions for methanogenesis (HCOO(-) and inoculum concentration, pH and duration of incubation) were assessed, an experiment with initial 31 replicates was run. Diluted fermenter sludge was used as inoculum, and process parameters including the pH, quality and quantity of the produced biogas and the concentrations of volatile fatty acids and HCO(3) (-) were determined. Remarkably, after 5 days of incubation the highest CH(4) production was calculated for a HCOO(-) concentration of 200 mmol L(-1), a concentration, however, which might not occur in situ. During the phase of high CH(4) production HCOO(-) was degraded with a rate of 1.5 mmol L(-1) h(-1), and distinct changes of Gibbs free energy for several reactions were observed. Based on denaturing high-performance liquid chromatography, denaturing gradient gel electrophoresis, and additional subsequent sequencing approaches the hydrogenotrophic Methanothermobacter wolfeii was the dominant methanogen responsible for CH(4) production. Further confirmation was achieved due to the detection of autofluorescing rods with a size of up to ~3 µm, which were often arranged in pairs and chains. It was shown that even high concentrations of HCOO(-) are readily degraded, which might lead to an underestimation of both, the concentration and thus, the importance of HCOO(-) in anaerobic digestion.
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Affiliation(s)
- Philipp Lins
- University of Innsbruck, Institute of Microbiology, Innsbruck, Austria.
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18
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Liaw HJ, Mah RA. Isolation and Characterization of Haloanaerobacter chitinovorans gen. nov., sp. nov., a Halophilic, Anaerobic, Chitinolytic Bacterium from a Solar Saltern. Appl Environ Microbiol 2010; 58:260-6. [PMID: 16348626 PMCID: PMC195201 DOI: 10.1128/aem.58.1.260-266.1992] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two halophilic anaerobic bacteria, one of which had chitinolytic activity, were isolated from a solar saltern in southern California. These organisms were long, gram-negative, motile, flexible rods. The biochemical and physiological characteristics of these bacteria were very similar but were different from the characteristics of other haloanaerobic bacteria. Both grew at salt concentrations ranging from 0.5 to 5 M and at temperatures ranging from 23 to 50 degrees C. They were sensitive to chloramphenicol but resistant to penicillin, carbenicillin, d-cycloserine, streptomycin, and tetracycline. An analysis of DNAs and whole-cell proteins showed that they were closely related taxonomically and distinguishable from other halophilic anaerobic bacteria. They exhibited 92.3 to 100% DNA homology as determined by DNA-DNA hybridization. The guanine-plus-cytosine contents of their DNAs were 34.8+/-1 mol%. The two isolates, strains W5C8 and W3C1, differed from other halophilic anaerobic bacteria sufficiently to support establishment of a new genus and species, Haloanaerobacter chitinovorans. Strain W5C8 exhibited chitinolytic activity and is designated the type strain. Two chitin-induced extracellular proteins with molecular weights of 38 x 10 and 40 x 10 were detected in strain W5C8.
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Affiliation(s)
- H J Liaw
- Department of Environmental Health Sciences, and Department of Microbiology, University of California, Los Angeles, California 90024-1772
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Holmes S, Senior E, Watson-Craik IA. Interactive effects of the electron acceptor sulphate and o-cresol on the methanogenic degradation of hexanoate. WATER RESEARCH 2002; 36:561-576. [PMID: 11827318 DOI: 10.1016/s0043-1354(01)00249-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A three-stage continuous culture system was used to segregate the component microbial groups of a methanogenic hexanoate-degrading association enriched from anaerobic refuse. The inhibitory effects of o-cresol concentrations (2-20 mM) on the fermentative, acetogenic, sulphate-reducing and methanogenic bacteria were then assessed in the presence of either 1.4 or 3.5 mM sulphate in the influent medium. The sulphate-reducing bacteria (SRB) in the 1.4 mM sulphate-supplemented systems were the most sensitive to o-cresol, with 29.3 and 56.6% inhibition on supplementation with 4 and 6 mM o-cresol, respectively. With 3.5mM supplementation, inhibition was 4.5 and 19.4%, respectively. Methanogenesis was not inhibited by concentrations < 10 mM o-cresol, and complete inhibition was recorded only at concentrations > or = 10 mM. Both fermentation and acetogenesis were affected by inhibition of the electron sinks. The increase in influent sulphate concentration promoted electron flow to sulphidogenesis, as predicted on thermodynamic criteria, but did not affect the relative sensitivity of the different physiological groups.
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Affiliation(s)
- Sulisti Holmes
- Department of Bioscience and Biotechnology, University of Strathclyde, Glasgow, UK
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Mukhopadhyay B, Johnson EF, Wolfe RS. Reactor-scale cultivation of the hyperthermophilic methanarchaeon Methanococcus jannaschii to high cell densities. Appl Environ Microbiol 1999; 65:5059-65. [PMID: 10543823 PMCID: PMC91681 DOI: 10.1128/aem.65.11.5059-5065.1999] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from approximately 0.5 to approximately 7.5 g of packed wet cells ( approximately 1.8 g dry cell mass) under autotrophic growth conditions and to approximately 8.5 g of packed wet cells ( approximately 2 g dry cell mass) with yeast extract (2 g liter(-1)) and tryptone (2 g liter(-1)) as medium supplements. For growth in a sealed bottle it was necessary to add Se to the medium, and a level of 2 microM for added Se gave the highest final cell yield. In a reactor M. jannaschii grew without added Se in the medium; it is plausible that the cells received Se as a contaminant from the reactor vessel and the H(2)S supply. But, for the optimal performance of a reactor culture, an addition of Se to a final concentration of 50 to 100 microM was needed. Also, cell growth in a reactor culture was inhibited at much higher Se concentrations. These observations and the data from previous work with methanogen cell extracts (B. C. McBride and R. S. Wolfe, Biochemistry 10:4312-4317, 1971) suggested that from a continuously sparged reactor culture Se was lost in the exhaust gas as volatile selenides, and this loss raised the apparent required level of and tolerance for Se. In spite of having a proteinaceous cell wall, M. jannaschii withstood an impeller tip speed of 235.5 cms(-1), which was optimal for achieving high cell density and also was the higher limit for the tolerated shear rate. The organism secreted one or more acidic compounds, which lowered pH in cultures without pH control; this secretion continued even after cessation of growth.
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Affiliation(s)
- B Mukhopadhyay
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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21
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Yamaguchi M, Minami K. Production of acetic acid from methanol by thermophilic Methanosarcina sp.: Acetate production as an index in abnormal methane fermentation. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0922-338x(98)80121-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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22
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Leadbetter JR, Breznak JA. Physiological ecology of Methanobrevibacter cuticularis sp. nov. and Methanobrevibacter curvatus sp. nov., isolated from the hindgut of the termite Reticulitermes flavipes. Appl Environ Microbiol 1996; 62:3620-31. [PMID: 8837417 PMCID: PMC168169 DOI: 10.1128/aem.62.10.3620-3631.1996] [Citation(s) in RCA: 216] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Two morphologically distinct, H2- and CO2-utilizing methanogens were isolated from gut homogenates of the subterranean termite, Reticulitermes-flavipes (Kollar) (Rhinotermitidae). Strain RFM-1 was a short straight rod (0.4 by 1.2 micron), whereas strain RFM-2 was a slightly curved rod (0.34 by 1.6 microns) that possessed polar fibers. Their morphology, gram-positive staining reaction, resistance to cell lysis by chemical agents, and narrow range of utilizable substracts were typical of species belonging to the family Methanobacteriaceae. Analysis of the nearly complete sequences of the small-subunit rRNA-encoding genes confirmed this affiliation and supported their recognition as new species of Methanobrevibacter: M. cuticularis (RFM-1) and M. curvatus (RFM-2). The per cell rates of methanogenesis by strains RFM-1 and RFM-2 in vitro, taken together with their in situ population densities (ca. 10(6) cells.gut-1; equivalent to 10(9) cells . ml of gut fluid-1), could fully account for the rate of methane emission by the live termites. UV epifluorescence and electron microscopy confirmed that RFM-1- and RFM-2-type cells were the dominant methanogens in R.flavipes collected in Michigan (but were not the only methanogens associated with this species) and that they colonized the peripheral, microoxic region of the hindgut, i.e., residing on or near the hindgut epithelium and also attached to filamentous prokaryotes associated with the gut wall. An examination of their oxygen tolerance revealed that both strains possessed catalase-like activity. Moreover, when dispersed in tubes or agar medium under H2-CO2-O2 (75: 18.8:6.2, vol/vol/vol), both strains grew to form a thin plate about 6 mm below the meniscus, just beneath the oxic-anoxic interface. Such growth plates were capable of mediating a net consumption of O2 that otherwise penetrated much deeper into uninoculated control tubes. Similar results were obtained with an authentic strain of Methanobrevibacter arboriphilicus. This is the first detailed description of an important and often cited but poorly understood component of the termite gut microbiota.
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Affiliation(s)
- J R Leadbetter
- Department of Microbiology, Michigan State University, East Lansing 48824-1101, USA
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23
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Freedman DL, Gossett JM. Biodegradation of dichloromethane and its utilization as a growth substrate under methanogenic conditions. Appl Environ Microbiol 1991; 57:2847-57. [PMID: 1746945 PMCID: PMC183885 DOI: 10.1128/aem.57.10.2847-2857.1991] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Biodegradation of dichloromethane (DCM) to environmentally acceptable products was demonstrated under methanogenic conditions (35 degrees C). When DCM was supplied to enrichment cultures as the sole organic compound at a low enough concentration to avoid inhibition of methanogenesis, the molar ratio of CH4 formed to DCM consumed (0.473) was very close to the amount predicted by stoichiometric conservation of electrons. DCM degradation was also demonstrated when methanogenesis was partially inhibited (with 0.5 to 1.5 mM 2-bromoethanesulfonate or approximately 2 mM DCM) or completely stopped (with 50 to 55.5 mM 2-bromoethanesulfonate). Addition of a eubacterial inhibitor (vancomycin, 100 mg/liter) greatly reduced the rate of DCM degradation. 14CO2 was the principal product of [14C]DCM degradation, followed by 14CH4 (when methanogenesis was uninhibited) or 14CH3COOH (when methanogenesis was partially or completely inhibited). Hydrogen accumulated during DCM degradation and then returned to background levels when DCM was consumed. These results suggested that nonmethanogenic organisms mediated DCM degradation, oxidizing a portion to CO2 and fermenting the remainder to acetate; acetate formation suggested involvement of an acetogen. Methanogens in the enrichment culture then converted the products of DCM degradation to CH4. Aceticlastic methanogens were more easily inhibited by 2-bromoethanesulfonate and DCM than were CO2-reducing methanogens. When DCM was the sole organic-carbon and electron donor source supplied, its use as a growth substrate was demonstrated. The highest observed yield was 0.085 g of suspended organic carbon formed per g of DCM carbon consumed. Approximately 85% of the biomass formed was attributable to the growth of nonmethanogens, and 15% was attributable to methanogens.
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Affiliation(s)
- D L Freedman
- Department of Civil Engineering, University of Illinois, Urbana 61801
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Abstract
We know of three routes that organisms have evolved to synthesize complex organic molecules from CO2: the Calvin cycle, the reverse tricarboxylic acid cycle, and the reductive acetyl-CoA pathway. This review describes the enzymatic steps involved in the acetyl-CoA pathway, also called the Wood pathway, which is the major mechanism of CO2 fixation under anaerobic conditions. The acetyl-CoA pathway is also able to form acetyl-CoA from carbon monoxide. There are two parts to the acetyl-CoA pathway: (1) reduction of CO2 to methyltetrahydrofolate (methyl-H4folate) and (2) synthesis of acetyl-CoA from methyl-H4folate, a carboxyl donor such as CO or CO2, and CoA. This pathway is unique in that the major intermediates are enzyme-bound and are often organometallic complexes. Our current understanding of the pathway is based on radioactive and stable isotope tracer studies, purification of the component enzymes (some extremely oxygen sensitive), and identification of the enzyme-bound intermediates by chromatographic, spectroscopic, and electrochemical techniques. This review describes the remarkable series of enzymatic steps involved in acetyl-CoA formation by this pathway that is a key component of the global carbon cycle.
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Affiliation(s)
- S W Ragsdale
- Department of Chemistry, University of Wisconsin-Milwaukee
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Dierick NA, Vervaeke IJ, Decuypere JA, Henderickx HK. Bacterial protein synthesis in relation to organic matter digestion in the hindgut of growing pigs; contribution of hindgut fermentation to total energy supply and growth performances. J Anim Physiol Anim Nutr (Berl) 1990. [DOI: 10.1111/j.1439-0396.1990.tb00139.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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