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Eam H, Ko D, Lee C, Myung J. Methylosinus trichosporium OB3b bioaugmentation unleashes polyhydroxybutyrate-accumulating potential in waste-activated sludge. Microb Cell Fact 2024; 23:160. [PMID: 38822346 PMCID: PMC11140957 DOI: 10.1186/s12934-024-02442-w] [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: 01/29/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024] Open
Abstract
BACKGROUND Wastewater treatment plants contribute approximately 6% of anthropogenic methane emissions. Methanotrophs, capable of converting methane into polyhydroxybutyrate (PHB), offer a promising solution for utilizing methane as a carbon source, using activated sludge as a seed culture for PHB production. However, maintaining and enriching PHB-accumulating methanotrophic communities poses challenges. RESULTS This study investigated the potential of Methylosinus trichosporium OB3b to bioaugment PHB-accumulating methanotrophic consortium within activated sludge to enhance PHB production. Waste-activated sludges with varying ratios of M. trichosporium OB3b (1:0, 1:1, 1:4, and 0:1) were cultivated. The results revealed substantial growth and methane consumption in waste-activated sludge with M. trichosporium OB3b-amended cultures, particularly in a 1:1 ratio. Enhanced PHB accumulation, reaching 37.1% in the same ratio culture, indicates the dominance of Type II methanotrophs. Quantification of methanotrophs by digital polymerase chain reaction showed gradual increases in Type II methanotrophs, correlating with increased PHB production. However, while initial bioaugmentation of M. trichosporium OB3b was observed, its presence decreased in subsequent cycles, indicating the dominance of other Type II methanotrophs. Microbial community analysis highlighted the successful enrichment of Type II methanotrophs-dominated cultures due to the addition of M. trichosporium OB3b, outcompeting Type I methanotrophs. Methylocystis and Methylophilus spp. were the most abundant in M. trichosporium OB3b-amended cultures. CONCLUSIONS Bioaugmentation strategies, leveraging M. trichosporium OB3b could significantly enhance PHB production and foster the enrichment of PHB-accumulating methanotrophs in activated sludge. These findings contribute to integrating PHB production in wastewater treatment plants, providing a sustainable solution for resource recovery.
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Affiliation(s)
- Hyerim Eam
- Department of Civil and Environmental Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Dayoung Ko
- Department of Civil, Urban, Earth, and Environmental Engineering, UNIST, Ulsan, 44919, Republic of Korea
| | - Changsoo Lee
- Department of Civil, Urban, Earth, and Environmental Engineering, UNIST, Ulsan, 44919, Republic of Korea
| | - Jaewook Myung
- Department of Civil and Environmental Engineering, KAIST, Daejeon, 34141, Republic of Korea.
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Hirayama H, Takaki Y, Abe M, Miyazaki M, Uematsu K, Matsui Y, Takai K. Methylomarinovum tepidoasis sp. nov., a moderately thermophilic methanotroph of the family Methylothermaceae isolated from a deep-sea hydrothermal field. Int J Syst Evol Microbiol 2024; 74:006288. [PMID: 38478579 PMCID: PMC10950024 DOI: 10.1099/ijsem.0.006288] [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: 07/27/2023] [Accepted: 02/24/2024] [Indexed: 03/21/2024] Open
Abstract
A novel aerobic methanotrophic bacterium, designated as strain IN45T, was isolated from in situ colonisation systems deployed at the Iheya North deep-sea hydrothermal field in the mid-Okinawa Trough. IN45T was a moderately thermophilic obligate methanotroph that grew only on methane or methanol at temperatures between 25 and 56 °C (optimum 45-50 °C). It was an oval-shaped, Gram-reaction-negative, motile bacterium with a single polar flagellum and an intracytoplasmic membrane system. It required 1.5-4.0 % (w/v) NaCl (optimum 2-3 %) for growth. The major phospholipid fatty acids were C16 : 1ω7c, C16 : 0 and C18 : 1ω7c. The major isoprenoid quinone was Q-8. The 16S rRNA gene sequence comparison revealed 99.1 % sequence identity with Methylomarinovum caldicuralii IT-9T, the only species of the genus Methylomarinovum with a validly published name within the family Methylothermaceae. The complete genome sequence of IN45T consisted of a 2.42-Mbp chromosome (DNA G+C content, 64.1 mol%) and a 20.5-kbp plasmid. The genome encodes genes for particulate methane monooxygenase and two types of methanol dehydrogenase (mxaFI and xoxF). Genes involved in the ribulose monophosphate pathway for carbon assimilation are encoded, but the transaldolase gene was not found. The genome indicated that IN45T performs partial denitrification of nitrate to N2O, and its occurrence was indirectly confirmed by N2O production in cultures grown with nitrate. Genomic relatedness indices between the complete genome sequences of IN45T and M. caldicuralii IT-9T, such as digital DNA-DNA hybridisation (51.2 %), average nucleotide identity (92.94 %) and average amino acid identity (93.21 %), indicated that these two methanotrophs should be separated at the species level. On the basis of these results, strain IN45T represents a novel species, for which we propose the name Methylomarinovum tepidoasis sp. nov. with IN45T (=JCM 35101T =DSM 113422T) as the type strain.
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Affiliation(s)
- Hisako Hirayama
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa, Japan
| | - Yoshihiro Takaki
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa, Japan
| | - Mariko Abe
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa, Japan
| | - Masayuki Miyazaki
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa, Japan
| | | | - Yohei Matsui
- Research Institute for Global Change (RIGC), JAMSTEC, Yokosuka, Kanagawa, Japan
| | - Ken Takai
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa, Japan
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Guo W, He R, Zhao Y, Li D. Imbalanced metabolism induced NH 4+ accumulation and its effect on the central metabolism of Methylomonas sp. ZR1. Int Microbiol 2024; 27:49-66. [PMID: 38038804 DOI: 10.1007/s10123-023-00457-8] [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: 08/15/2022] [Revised: 07/23/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023]
Abstract
Nitrogen and carbon are the two most essential nutrient elements, and their metabolism is tightly coupled in single carbon metabolic microorganisms. However, the nitrogen metabolism and the nitrogen/carbon (N/C) metabolic balance in single-carbon metabolism is poorly studied. In this study, the nitrogen metabolism pattern of the fast growing methanotrophs Methylomonas sp. ZR1 grown in methane and methanol was studied. Effect study of different nitrogen sources on the cell growth of ZR1 indicates that nitrate salts are the best nitrogen source supporting the growth of ZR1 using methane and methanol as carbon source. However, its metabolic intermediate ammonium was found to accumulate with high N/C ratio in the medium and consequently inhibit the growth of ZR1. Studies of carbon and nitrogen metabolic kinetic under different N/C ratio conditions indicate that the accumulation of NH4+ is caused by the imbalanced nitrogen and carbon metabolism in ZR1. Feeding carbon skeleton α-ketoglutaric acid could effectively relieve the inhibition effect of NH4+ on the growth of ZR1, which further confirms this assumption. qPCR analysis of the expression level of the central metabolic key enzyme gene indicates that the nitrogen metabolic intermediate ammonium has strong regulation effect on the central nitrogen and carbon metabolism in ZR1. qPCR-combined genomic analysis confirms that a third ammonium assimilation pathway glycine synthesis system is operated in ZR1 to balance the nitrogen and carbon metabolism. Based on the qPCR result, it was also found that ZR1 employs two strategies to relieve ammonium stress in the presence of ammonium: assimilating excess ammonium or cutting off the nitrogen reduction reactions according to the available C1 substrate. Validating the connections between single-carbon and nitrogen metabolism and studying the accumulation and assimilation mechanism of ammonium will contribute to understand how nitrogen regulates cellular growth in single-carbon metabolic microorganisms.
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Affiliation(s)
- Wei Guo
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Science, 32 West 7Th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China.
| | - Ronglin He
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Science, 32 West 7Th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Yujie Zhao
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Science, 32 West 7Th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Demao Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Science, 32 West 7Th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
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Houghton KM, Carere CR, Stott MB, McDonald IR. Thermophilic methane oxidation is widespread in Aotearoa-New Zealand geothermal fields. Front Microbiol 2023; 14:1253773. [PMID: 37720161 PMCID: PMC10502179 DOI: 10.3389/fmicb.2023.1253773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023] Open
Abstract
Geothermal areas represent substantial point sources for greenhouse gas emissions such as methane. While it is known that methanotrophic microorganisms act as a biofilter, decreasing the efflux of methane in most soils to the atmosphere, the diversity and the extent to which methane is consumed by thermophilic microorganisms in geothermal ecosystems has not been widely explored. To determine the extent of biologically mediated methane oxidation at elevated temperatures, we set up 57 microcosms using soils from 14 Aotearoa-New Zealand geothermal fields and show that moderately thermophilic (>40°C) and thermophilic (>60°C) methane oxidation is common across the region. Methane oxidation was detected in 54% (n = 31) of the geothermal soil microcosms tested at temperatures up to 75°C (pH 1.5-8.1), with oxidation rates ranging from 0.5 to 17.4 μmol g-1 d-1 wet weight. The abundance of known aerobic methanotrophs (up to 60.7% Methylacidiphilum and 11.2% Methylothermus) and putative anaerobic methanotrophs (up to 76.7% Bathyarchaeota) provides some explanation for the rapid rates of methane oxidation observed in microcosms. However, not all methane oxidation was attributable to known taxa; in some methane-consuming microcosms we detected methanotroph taxa in conditions outside of their known temperature range for growth, and in other examples, we observed methane oxidation in the absence of known methanotrophs through 16S rRNA gene sequencing. Both of these observations suggest unidentified methane oxidizing microorganisms or undescribed methanotrophic syntrophic associations may also be present. Subsequent enrichment cultures from microcosms yielded communities not predicted by the original diversity studies and showed rates inconsistent with microcosms (≤24.5 μmol d-1), highlighting difficulties in culturing representative thermophilic methanotrophs. Finally, to determine the active methane oxidation processes, we attempted to elucidate metabolic pathways from two enrichment cultures actively oxidizing methane using metatranscriptomics. The most highly expressed genes in both enrichments (methane monooxygenases, methanol dehydrogenases and PqqA precursor peptides) were related to methanotrophs from Methylococcaceae, Methylocystaceae and Methylothermaceae. This is the first example of using metatranscriptomics to investigate methanotrophs from geothermal environments and gives insight into the metabolic pathways involved in thermophilic methanotrophy.
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Affiliation(s)
- Karen M. Houghton
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, New Zealand
| | - Carlo R. Carere
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Tari Pūhanga Tukanga Matū | Department of Chemical and Process Engineering, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, New Zealand
| | - Matthew B. Stott
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, New Zealand
| | - Ian R. McDonald
- Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, New Zealand
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Sharma U, Rawat D, Mukherjee P, Farooqi F, Mishra V, Sharma RS. Ecological life strategies of microbes in response to antibiotics as a driving factor in soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158791. [PMID: 36108841 DOI: 10.1016/j.scitotenv.2022.158791] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/31/2022] [Accepted: 09/11/2022] [Indexed: 06/15/2023]
Abstract
Antibiotics as a selection pressure driving the evolution of soil microbial communities is not well understood. Since microbial functions govern ecosystem services, an ecological framework is required to understand and predict antibiotic-induced functional and structural changes in microbial communities. Therefore, metagenomic studies explaining the impacts of antibiotics on soil microbial communities were mined, and alterations in microbial taxa were analyzed through an ecological lens using Grimes's Competitor-Stress tolerator-Ruderal (CSR) model. We propose considering antibiotics as the primary abiotic factor mentioned in the CSR model and classifying non-susceptible microbial taxa as degraders, resistant, and resilient groups analogous to competitors, stress tolerators, and ruderal strategists, respectively. Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria were among the phyla harboring most members with antibiotic-resistant groups. However, some antibiotic-resistant microbes in these phyla could not only tolerate but also subsist solely on antibiotics, while others degraded antibiotics as a part of secondary metabolism. Irrespective of their taxonomic affiliation, microbes with each life strategy displayed similar phenotypic characteristics. Therefore, it is recommended to consider microbial functional traits associated with each life strategy while analyzing the ecological impacts of antibiotics. Also, potential ecological crises posed by antibiotics through changes in microbial community and ecosystem functions were visualized. Applying ecological theory to understand and predict antibiotics-induced changes in microbial communities will also provide better insight into microbial behavior in the background of emerging contaminants and help develop a robust ecological classification system of microbes.
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Affiliation(s)
- Udita Sharma
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India
| | - Deepak Rawat
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India; Department of Environmental Studies, Janki Devi Memorial College, University of Delhi, Delhi 110060, India
| | - Paromita Mukherjee
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India
| | - Furqan Farooqi
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India
| | - Vandana Mishra
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India; Centre for Interdisciplinary Studies on Mountain & Hill Environment (CISMHE), University of Delhi, Delhi 110007, India.
| | - Radhey Shyam Sharma
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi 110007, India; Delhi School of Climate Change & Sustainability, Institute of Eminence, University of Delhi, Delhi 110007, India.
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6
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Methylocystis sp. Strain SC2 Acclimatizes to Increasing NH 4+ Levels by a Precise Rebalancing of Enzymes and Osmolyte Composition. mSystems 2022; 7:e0040322. [PMID: 36154142 PMCID: PMC9600857 DOI: 10.1128/msystems.00403-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A high NH4+ load is known to inhibit bacterial methane oxidation. This is due to a competition between CH4 and NH3 for the active site of particulate methane monooxygenase (pMMO), which converts CH4 to CH3OH. Here, we combined global proteomics with amino acid profiling and nitrogen oxides measurements to elucidate the cellular acclimatization response of Methylocystis sp. strain SC2 to high NH4+ levels. Relative to 1 mM NH4+, a high (50 mM and 75 mM) NH4+ load under CH4-replete conditions significantly increased the lag phase duration required for proteome adjustment. The number of differentially regulated proteins was highly significantly correlated with an increasing NH4+ load. The cellular responses to increasing ionic and osmotic stress involved a significant upregulation of stress-responsive proteins, the K+ "salt-in" strategy, the synthesis of compatible solutes (glutamate and proline), and the induction of the glutathione metabolism pathway. A significant increase in the apparent Km value for CH4 oxidation during the growth phase was indicative of increased pMMO-based oxidation of NH3 to toxic hydroxylamine. The detoxifying activity of hydroxlyamine oxidoreductase (HAO) led to a significant accumulation of NO2- and, upon decreasing O2 tension, N2O. Nitric oxide reductase and hybrid cluster proteins (Hcps) were the candidate enzymes for the production of N2O. In summary, strain SC2 has the capacity to precisely rebalance enzymes and osmolyte composition in response to increasing NH4+ exposure, but the need to simultaneously combat both ionic-osmotic stress and the toxic effects of hydroxylamine may be the reason why its acclimatization capacity is limited to 75 mM NH4+. IMPORTANCE In addition to reducing CH4 emissions from wetlands and landfills, the activity of alphaproteobacterial methane oxidizers of the genus Methylocystis contributes to the sink capacity of forest and grassland soils for atmospheric methane. The methane-oxidizing activity of Methylocystis spp. is, however, sensitive to high NH4+ concentrations. This is due to the competition of CH4 and NH3 for the active site of particulate methane monooxygenase, thereby resulting in the production of toxic hydroxylamine with an increasing NH4+ load. An understanding of the physiological and molecular response mechanisms of Methylocystis spp. is therefore of great importance. Here, we combined global proteomics with amino acid profiling and NOx measurements to disentangle the cellular mechanisms underlying the acclimatization of Methylocystis sp. strain SC2 to an increasing NH4+ load.
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Rodríguez Y, García S, Pérez R, Lebrero R, Muñoz R. Optimization of nitrogen feeding strategies for improving polyhydroxybutyrate production from biogas by Methylocystis parvus str. OBBP in a stirred tank reactor. CHEMOSPHERE 2022; 299:134443. [PMID: 35364084 DOI: 10.1016/j.chemosphere.2022.134443] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 03/07/2022] [Accepted: 03/24/2022] [Indexed: 06/14/2023]
Abstract
The design of efficient cultivation strategies to produce bioplastics from biogas is crucial for the implementation of this biorefinery process. In this work, biogas-based polyhydroxybutyrate (PHB) production and CH4 biodegradation performance was investigated for the first time in a stirred tank bioreactor inoculated with Methylocystis parvus str. OBBP. Decreasing nitrogen loading rates in continuous mode and alternating feast:famine regimes of 24 h-cycles, and alternating feast:famine regimes of 24 h:24 h and 24 h:48 h were tested. Continuous N feeding did not support an effective PHB production despite the occurrence of nitrogen limiting conditions. Feast-famine cycles of 24 h:24 h (with 50% stoichiometric nitrogen supply) supported the maximum PHB production (20 g-PHB m-3 d-1) without compromising the CH4-elimination capacity (25 g m-3 h-1) of the system. Feast:famine ratios ≤1:2 entailed the deterioration of process performance at stoichiometric nitrogen inputs ≤60%.
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Affiliation(s)
- Yadira Rodríguez
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
| | - Silvia García
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
| | - Rebeca Pérez
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
| | - Raquel Lebrero
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
| | - Raúl Muñoz
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
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8
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Kaupper T, Mendes LW, Poehlein A, Frohloff D, Rohrbach S, Horn MA, Ho A. The methane-driven interaction network in terrestrial methane hotspots. ENVIRONMENTAL MICROBIOME 2022; 17:15. [PMID: 35382875 PMCID: PMC8981696 DOI: 10.1186/s40793-022-00409-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Biological interaction affects diverse facets of microbial life by modulating the activity, diversity, abundance, and composition of microbial communities. Aerobic methane oxidation is a community function, with emergent community traits arising from the interaction of the methane-oxidizers (methanotrophs) and non-methanotrophs. Yet little is known of the spatial and temporal organization of these interaction networks in naturally-occurring complex communities. We hypothesized that the assembled bacterial community of the interaction network in methane hotspots would converge, driven by high substrate availability that favors specific methanotrophs, and in turn influences the recruitment of non-methanotrophs. These environments would also share more co-occurring than site-specific taxa. RESULTS We applied stable isotope probing (SIP) using 13C-CH4 coupled to a co-occurrence network analysis to probe trophic interactions in widespread methane-emitting environments, and over time. Network analysis revealed predominantly unique co-occurring taxa from different environments, indicating distinctly co-evolved communities more strongly influenced by other parameters than high methane availability. Also, results showed a narrower network topology range over time than between environments. Co-occurrence pattern points to Chthoniobacter as a relevant yet-unrecognized interacting partner particularly of the gammaproteobacterial methanotrophs, deserving future attention. In almost all instances, the networks derived from the 13C-CH4 incubation exhibited a less connected and complex topology than the networks derived from the unlabelledC-CH4 incubations, likely attributable to the exclusion of the inactive microbial population and spurious connections; DNA-based networks (without SIP) may thus overestimate the methane-dependent network complexity. CONCLUSION We demonstrated that site-specific environmental parameters more strongly shaped the co-occurrence of bacterial taxa than substrate availability. Given that members of the interactome without the capacity to oxidize methane can exert interaction-induced effects on community function, understanding the co-occurrence pattern of the methane-driven interaction network is key to elucidating community function, which goes beyond relating activity to community composition, abundances, and diversity. More generally, we provide a methodological strategy that substantiates the ecological linkages between potentially interacting microorganisms with broad applications to elucidate the role of microbial interaction in community function.
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Affiliation(s)
- Thomas Kaupper
- Institute for Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany
| | - Lucas W Mendes
- Center for Nuclear Energy in Agriculture, University of São Paulo CENA-USP, Piracicaba, SP, Brazil
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, George-August University Göttingen, Grisebachstr. 8, 37077, Göttingen, Germany
| | - Daria Frohloff
- Institute for Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany
| | - Stephan Rohrbach
- Institute for Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany
| | - Marcus A Horn
- Institute for Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany.
| | - Adrian Ho
- Institute for Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany.
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9
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Li C, Hambright KD, Bowen HG, Trammell MA, Grossart HP, Burford MA, Hamilton DP, Jiang H, Latour D, Meyer EI, Padisák J, Zamor RM, Krumholz LR. Global co-occurrence of methanogenic archaea and methanotrophic bacteria in Microcystis aggregates. Environ Microbiol 2021; 23:6503-6519. [PMID: 34327792 DOI: 10.1111/1462-2920.15691] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/26/2021] [Indexed: 11/29/2022]
Abstract
Global warming and eutrophication contribute to the worldwide increase in cyanobacterial blooms, and the level of cyanobacterial biomass is strongly associated with rises in methane emissions from surface lake waters. Hence, methane-metabolizing microorganisms may be important for modulating carbon flow in cyanobacterial blooms. Here, we surveyed methanogenic and methanotrophic communities associated with floating Microcystis aggregates in 10 lakes spanning four continents, through sequencing of 16S rRNA and functional marker genes. Methanogenic archaea (mainly Methanoregula and Methanosaeta) were detectable in 5 of the 10 lakes and constituted the majority (~50%-90%) of the archaeal community in these lakes. Three of the 10 lakes contained relatively more abundant methanotrophs than the other seven lakes, with the methanotrophic genera Methyloparacoccus, Crenothrix, and an uncultured species related to Methylobacter dominating and nearly exclusively found in each of those three lakes. These three are among the five lakes in which methanogens were observed. Operational taxonomic unit (OTU) richness and abundance of methanotrophs were strongly positively correlated with those of methanogens, suggesting that their activities may be coupled. These Microcystis-aggregate-associated methanotrophs may be responsible for a hitherto overlooked sink for methane in surface freshwaters, and their co-occurrence with methanogens sheds light on the methane cycle in cyanobacterial aggregates.
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Affiliation(s)
- Chuang Li
- Department of Microbiology and Plant Biology, Institute for Energy and the Environment, The University of Oklahoma, Norman, Ok, USA
| | - K David Hambright
- Plankton Ecology and Limnology Laboratory, Program in Ecology and Evolutionary Biology, and the Geographical Ecology Group, Department of Biology, The University of Oklahoma, Norman, OK, USA
| | - Hannah G Bowen
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Majoi A Trammell
- Biomedical Research Center, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Hans-Peter Grossart
- Department of Experimental Limnology, Leibniz Institute for Freshwater Ecology and Inland Fisheries, Stechlin, and Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany
| | - Michele A Burford
- Australian Rivers Institute and School of Environment and Science, Griffith University, Nathan, Qld, Australia
| | - David P Hamilton
- Australian Rivers Institute, Griffith University, Nathan, Qld, Australia
| | - Helong Jiang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China
| | - Delphine Latour
- Université Clermont Auvergne CNRS, LMGE, Aubière Cedex, France
| | - Elisabeth I Meyer
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Judit Padisák
- Research Group of Limnology, Centre of Natural Sciences, University of Pannonia, Veszprém, Hungary
| | | | - Lee R Krumholz
- Department of Microbiology and Plant Biology, Institute for Energy and the Environment, The University of Oklahoma, Norman, Ok, USA
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10
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Nijman TPA, Davidson TA, Weideveld STJ, Audet J, Esposito C, Levi EE, Ho A, Lamers LPM, Jeppesen E, Veraart AJ. Warming and eutrophication interactively drive changes in the methane-oxidizing community of shallow lakes. ISME COMMUNICATIONS 2021; 1:32. [PMID: 37938256 PMCID: PMC9723669 DOI: 10.1038/s43705-021-00026-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 06/14/2023]
Abstract
Freshwater ecosystems are the largest natural source of the greenhouse gas methane (CH4), with shallow lakes a particular hot spot. Eutrophication and warming generally increase lake CH4 emissions but their impacts on the sole biological methane sink-methane oxidation-and methane-oxidizer community dynamics are poorly understood. We used the world's longest-running freshwater climate-change mesocosm experiment to determine how methane-oxidizing bacterial (MOB) abundance and composition, and methane oxidation potential in the sediment respond to eutrophication, short-term nitrogen addition and warming. After nitrogen addition, MOB abundance and methane oxidation potential increased, while warming increased MOB abundance without altering methane oxidation potential. MOB community composition was driven by both temperature and nutrient availability. Eutrophication increased relative abundance of type I MOB Methyloparacoccus. Warming favoured type II MOB Methylocystis over type I MOB Methylomonadaceae, shifting the MOB community from type I dominance to type I and II co-dominance, thereby altering MOB community traits involved in growth and stress-responses. This shift to slower-growing MOB may explain why higher MOB abundance in warmed mesocosms did not coincide with higher methane oxidation potential. Overall, we show that eutrophication and warming differentially change the MOB community, resulting in an altered ability to mitigate CH4 emissions from shallow lakes.
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Affiliation(s)
- Thomas P A Nijman
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands.
| | - Thomas A Davidson
- Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark
- WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark
| | - Stefan T J Weideveld
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Joachim Audet
- Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark
- WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark
| | - Chiara Esposito
- Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark
- WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark
| | - Eti E Levi
- Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark
- WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark
| | - Adrian Ho
- Institute for Microbiology, Liebniz Universität Hannover, Hannover, Germany
| | - Leon P M Lamers
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Erik Jeppesen
- Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark
- WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark
- Sino-Danish Centre for Education and Research (SDC), University of Chinese Academy of Sciences, Beijing, China
- Limnology Laboratory, Department of Biological Sciences and Centre for Ecosystem Research and implementation, Middle East Technical University, Ankara, Turkey
- Institute of Marine Sciences, Middle East Technical University, Erdemli-Mersin, Turkey
| | - Annelies J Veraart
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
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11
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Liu D, Yang Y, Ai J, Li Y, Xing Y, Li J. Research on microbial structures, functions and metabolic pathways in an advanced denitrification system coupled with aerobic methane oxidation based on metagenomics. BIORESOURCE TECHNOLOGY 2021; 332:125047. [PMID: 33839509 DOI: 10.1016/j.biortech.2021.125047] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 06/12/2023]
Abstract
Methanotrophs can oxidize methane as the sole carbon and energy, and the resulting intermediate products can be simultaneously utilized by coexistent denitrifying bacteria to remove the nitrogen, which named Aerobic Methane Oxidation Coupled to Denitrification (AME-D). In this paper, an AME-D system was built in an improved denitrification bio-filter, to analyze the nitrogen removal efficiency and mechanism. The maximum TN removal rate reached 95.05%. As shown in Raman spectroscopy, in the effluent wave crests generated by the symmetric expansion and contraction of NO3- disappeared, and the distortion of olefin CH2 and C-OH stretching of alcohols appeared. Metagenomics revealed Methylotenera and Methylobacter were the dominated methanotrophs. There was a completed methane and nitrogen metabolism pathway with the synergism of nxrAB, narGHI, nasAB, pmo-amoABC and mmo genes. Dissimilatory reduction pathway was the primary nitrate removal pathway. Moreover, Bradyrhizobium could participate in methane and nitrogen metabolism simultaneously.
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Affiliation(s)
- Dengping Liu
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China
| | - Yanan Yang
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China; Sinopec Great Wall Energy and Chemical (Guizhou) Co., LTD, Zhijin, Guizhou 552100, China
| | - Jia Ai
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China
| | - Yancheng Li
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, Guizhou 550025, China.
| | - Yi Xing
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China; School of Energy and Environmental Engineering, University of Science & Technology Beijing, Beijing 100083, China
| | - Jiang Li
- College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 500025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, Guizhou 550025, China
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12
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Costa RB, Lens PNL, Foresti E. Methanotrophic denitrification in wastewater treatment: microbial aspects and engineering strategies. Crit Rev Biotechnol 2021; 42:145-161. [PMID: 34157918 DOI: 10.1080/07388551.2021.1931014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Anaerobic technologies are consolidated for sewage treatment and are the core processes for mining marketable products from waste streams. However, anaerobic effluents are supersaturated with methane, which represents a liability regarding greenhouse gas emissions. Meanwhile, anaerobic technologies are not capable of nitrogen removal, which is required to ensure environmental protection. Methane oxidation and denitrification processes can be combined to address both issues concurrently. Aerobic methane oxidizers can release intermediate organic compounds that can be used by conventional denitrifiers as electron donors. Alternatively, anoxic methanotrophic species combine methane oxidation with either nitrate or nitrite reduction in the same metabolism. Engineered systems need to overcome the long doubling times and low NOx consumption rates of anoxic methanotrophic microorganisms. Another commonly reported bottleneck of methanotrophic denitrification relates to gas-liquid mass transfer limitations. Although anaerobic effluents are supersaturated with methane, experimental setups usually rely on methane supply in a gaseous mode. Hence, possibilities for the application of methane-oxidation coupled to denitrification in full scale might be overlooked. Moreover, syntrophic relationships among methane oxidizers, denitrifiers, nitrifiers, and other microorganisms (such as anammox) are not well understood. Integrating mixed populations with various metabolic abilities could allow for more robust methane-driven wastewater denitrification systems. This review presents an overview of the metabolic capabilities of methane oxidation and denitrification and discusses technological aspects that allow for the application of methanotrophic denitrification at larger scales.
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Affiliation(s)
- R B Costa
- Department of Hydraulics and Sanitation, São Carlos School of Engineering (EESC), University of São Paulo (USP), São Carlos, Brazil.,National University of Ireland, Galway, Ireland
| | - P N L Lens
- National University of Ireland, Galway, Ireland
| | - E Foresti
- Department of Hydraulics and Sanitation, São Carlos School of Engineering (EESC), University of São Paulo (USP), São Carlos, Brazil
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13
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Guerrero-Cruz S, Vaksmaa A, Horn MA, Niemann H, Pijuan M, Ho A. Methanotrophs: Discoveries, Environmental Relevance, and a Perspective on Current and Future Applications. Front Microbiol 2021; 12:678057. [PMID: 34054786 PMCID: PMC8163242 DOI: 10.3389/fmicb.2021.678057] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
Methane is the final product of the anaerobic decomposition of organic matter. The conversion of organic matter to methane (methanogenesis) as a mechanism for energy conservation is exclusively attributed to the archaeal domain. Methane is oxidized by methanotrophic microorganisms using oxygen or alternative terminal electron acceptors. Aerobic methanotrophic bacteria belong to the phyla Proteobacteria and Verrucomicrobia, while anaerobic methane oxidation is also mediated by more recently discovered anaerobic methanotrophs with representatives in both the bacteria and the archaea domains. The anaerobic oxidation of methane is coupled to the reduction of nitrate, nitrite, iron, manganese, sulfate, and organic electron acceptors (e.g., humic substances) as terminal electron acceptors. This review highlights the relevance of methanotrophy in natural and anthropogenically influenced ecosystems, emphasizing the environmental conditions, distribution, function, co-existence, interactions, and the availability of electron acceptors that likely play a key role in regulating their function. A systematic overview of key aspects of ecology, physiology, metabolism, and genomics is crucial to understand the contribution of methanotrophs in the mitigation of methane efflux to the atmosphere. We give significance to the processes under microaerophilic and anaerobic conditions for both aerobic and anaerobic methane oxidizers. In the context of anthropogenically influenced ecosystems, we emphasize the current and potential future applications of methanotrophs from two different angles, namely methane mitigation in wastewater treatment through the application of anaerobic methanotrophs, and the biotechnological applications of aerobic methanotrophs in resource recovery from methane waste streams. Finally, we identify knowledge gaps that may lead to opportunities to harness further the biotechnological benefits of methanotrophs in methane mitigation and for the production of valuable bioproducts enabling a bio-based and circular economy.
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Affiliation(s)
- Simon Guerrero-Cruz
- Catalan Institute for Water Research (ICRA), Girona, Spain
- Universitat de Girona, Girona, Spain
| | - Annika Vaksmaa
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, ’t Horntje, Netherlands
| | - Marcus A. Horn
- Institute of Microbiology, Leibniz Universität Hannover, Hannover, Germany
| | - Helge Niemann
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, ’t Horntje, Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, Netherlands
- Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT the Arctic University of Norway, Tromsø, Norway
| | - Maite Pijuan
- Catalan Institute for Water Research (ICRA), Girona, Spain
- Universitat de Girona, Girona, Spain
| | - Adrian Ho
- Institute of Microbiology, Leibniz Universität Hannover, Hannover, Germany
- Division of Applied Life Sciences, Gyeongsang National University, Jinju, South Korea
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14
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Cordova-Gonzalez A, Birgel D, Kappler A, Peckmann J. Variation of salinity and nitrogen concentration affects the pentacyclic triterpenoid inventory of the haloalkaliphilic aerobic methanotrophic bacterium Methylotuvimicrobium alcaliphilum. Extremophiles 2021; 25:285-299. [PMID: 33866428 PMCID: PMC8102298 DOI: 10.1007/s00792-021-01228-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 04/01/2021] [Indexed: 11/30/2022]
Abstract
The occurrence and activity of aerobic methanotrophs are influenced by environmental conditions, including pH, temperature, salinity, methane and oxygen concentrations, and nutrient availability. Aerobic methanotrophs synthesize a variety of lipids important for cell functions. However, culture-based experiments studying the influence of environmental parameters on lipid production by aerobic methanotrophs are scarce. Such information is crucial to interpret lipid patterns of methanotrophic bacteria in the environment. In this study, the alkaliphilic strain Methylotuvimicrobium alcaliphilum was cultivated under different salinities and different nitrate concentrations to assess the effect of changing conditions on the inventory of pentacyclic triterpenoids. The results indicate that hopanoid abundance is enhanced at lower salinity and higher nitrate concentration. The production of most pentacyclic triterpenoids was favored at low salinity, especially for aminotriol. Interestingly, 3-methyl-aminotetrol and tetrahymanol were favored at higher salinity. Bacteriohopanepolyols (BHPs), particularly aminotriol and 3-methyl-aminotriol, increased considerably at higher nitrate concentrations. Four novel N-containing BHPs—aminodiol, 3-methyl-aminodiol, and isomers of aminotriol and 3-methyl-aminotriol—were identified. This study highlights the significance of environmental factors for bacterial lipid production and documents the need for cultivation studies under variable conditions to utilize the full potential of the biomarker concept.
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Affiliation(s)
- Alexmar Cordova-Gonzalez
- Institut für Geologie, Centrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Hamburg, Germany
| | - Daniel Birgel
- Institut für Geologie, Centrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Hamburg, Germany.
| | - Andreas Kappler
- Geomikrobiologie, Zentrum für Angewandte Geowissenschaften, Universität Tübingen, Tübingen, Germany
| | - Jörn Peckmann
- Institut für Geologie, Centrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Hamburg, Germany
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15
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Ho A, Mendes LW, Lee HJ, Kaupper T, Mo Y, Poehlein A, Bodelier PLE, Jia Z, Horn MA. Response of a methane-driven interaction network to stressor intensification. FEMS Microbiol Ecol 2021; 96:5898668. [PMID: 32857837 DOI: 10.1093/femsec/fiaa180] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/25/2020] [Indexed: 01/04/2023] Open
Abstract
Microorganisms may reciprocally select for specific interacting partners, forming a network with interdependent relationships. The methanotrophic interaction network, comprising methanotrophs and non-methanotrophs, is thought to modulate methane oxidation and give rise to emergent properties beneficial for the methanotrophs. Therefore, microbial interaction may become relevant for community functioning under stress. However, empirical validation of the role and stressor-induced response of the interaction network remains scarce. Here, we determined the response of a complex methane-driven interaction network to a stepwise increase in NH4Cl-induced stress (0.5-4.75 g L-1, in 0.25-0.5 g L-1 increments) using enrichment of a naturally occurring complex community derived from a paddy soil in laboratory-scale incubations. Although ammonium and intermediates of ammonium oxidation are known to inhibit methane oxidation, methanotrophic activity was unexpectedly detected even in incubations with high ammonium levels, albeit rates were significantly reduced. Sequencing analysis of the 16S rRNA and pmoA genes consistently revealed divergent communities in the reference and stressed incubations. The 16S rRNA-based co-occurrence network analysis revealed that NH4Cl-induced stress intensification resulted in a less complex and modular network, likely driven by less stable interaction. Interestingly, the non-methanotrophs formed the key nodes, and appear to be relevant members of the community. Overall, stressor intensification unravels the interaction network, with adverse consequences for community functioning.
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Affiliation(s)
- Adrian Ho
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
| | - Lucas W Mendes
- Center of Nuclear Energy in Agriculture, University of São Paulo (CENA-USP), Avenida Centenario 303, 13416-000, Piracicaba-SP, Brazil
| | - Hyo Jung Lee
- Department of Biology, Kunsan National University, 558 Daehak-ro, Gunsan-si 54150, Republic of Korea
| | - Thomas Kaupper
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
| | - Yongliang Mo
- Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Xuan-Wu District, Nanjing 210008, China
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, the Netherlands
| | - Zhongjun Jia
- Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Xuan-Wu District, Nanjing 210008, China
| | - Marcus A Horn
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
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16
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Schmitz RA, Peeters SH, Versantvoort W, Picone N, Pol A, Jetten MSM, Op den Camp HJM. Verrucomicrobial methanotrophs: ecophysiology of metabolically versatile acidophiles. FEMS Microbiol Rev 2021; 45:6125968. [PMID: 33524112 PMCID: PMC8498564 DOI: 10.1093/femsre/fuab007] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/15/2021] [Indexed: 12/26/2022] Open
Abstract
Methanotrophs are an important group of microorganisms that counteract methane emissions to the atmosphere. Methane-oxidising bacteria of the Alpha- and Gammaproteobacteria have been studied for over a century, while methanotrophs of the phylum Verrucomicrobia are a more recent discovery. Verrucomicrobial methanotrophs are extremophiles that live in very acidic geothermal ecosystems. Currently, more than a dozen strains have been isolated, belonging to the genera Methylacidiphilum and Methylacidimicrobium. Initially, these methanotrophs were thought to be metabolically confined. However, genomic analyses and physiological and biochemical experiments over the past years revealed that verrucomicrobial methanotrophs, as well as proteobacterial methanotrophs, are much more metabolically versatile than previously assumed. Several inorganic gases and other molecules present in acidic geothermal ecosystems can be utilised, such as methane, hydrogen gas, carbon dioxide, ammonium, nitrogen gas and perhaps also hydrogen sulfide. Verrucomicrobial methanotrophs could therefore represent key players in multiple volcanic nutrient cycles and in the mitigation of greenhouse gas emissions from geothermal ecosystems. Here, we summarise the current knowledge on verrucomicrobial methanotrophs with respect to their metabolic versatility and discuss the factors that determine their diversity in their natural environment. In addition, key metabolic, morphological and ecological characteristics of verrucomicrobial and proteobacterial methanotrophs are reviewed.
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Affiliation(s)
- Rob A Schmitz
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Stijn H Peeters
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Wouter Versantvoort
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Nunzia Picone
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Arjan Pol
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Huub J M Op den Camp
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
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17
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Sabu EA, Gonsalves MJ, Sreepada RA, Shivaramu MS, Ramaiah N. Evaluation of the Physiological Bacterial Groups in a Tropical Biosecured, Zero-Exchange System Growing Whiteleg Shrimp, Litopenaeus vannamei. MICROBIAL ECOLOGY 2021; 81:335-346. [PMID: 32880700 DOI: 10.1007/s00248-020-01575-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
To elucidate the individual and multiple roles of physiological bacterial groups involved in biogeochemical cycles of carbon, nitrogen, phosphorus and sulfur, the changes in the abundance of aerobic bacteria (heterotrophs, methane oxidizers, ammonia oxidizers, sulfur oxidizers, phosphate solubilizers, phosphate accumulators) and anaerobic bacteria (total anaerobes, nitrate reducers, denitrifiers and sulfate reducers) were investigated in a biosecured, zero-exchange system stocked with whiteleg shrimp, Litopenaeus vannamei for one production cycle. Key water quality parameters during the 96-day production cycle fell within the normal range for L. vannamei culture. Results of Spearman's correlation matrix revealed that different sets of variables correlated at varying levels of significance of the interrelationships between bacterial abundances and water quality parameters. The three nitrogenous species (ammonia, nitrite and nitrate) strongly influenced the physiological bacterial groups' abundance. The strong relationship of bacterial groups with phytoplankton biomass and abundance clearly showed the trophic interconnections in nutrient exchange/recycling. Canonical correspondence analysis performed to assess the total variation revealed that the three dissolved nitrogen species followed by salinity, temperature, phytoplankton biomass and pH collectively accounted for as much as 82% of the total variation. In conclusion, the results of the study revealed that the major drivers that interweaved biogeochemical cycles are the three dissolved nitrogen species, which microbially mediated various aerobic-anaerobic assimilation/dissimilation processes in the pond ecosystem. Considering the pond microbial ecology becoming an important management tool where applied research could improve the economic and environmental sustainability of the aquaculture industry, the findings of the present study are practically relevant.
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Affiliation(s)
- Elaine A Sabu
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India
- School of Earth, Ocean and Atmospheric Sciences, Goa University, Taleigao Plateau, Goa, 403 206, India
| | - Maria Judith Gonsalves
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India.
| | - R A Sreepada
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India
| | - Mamatha S Shivaramu
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India
- Department of Food Protectants & Infestation Control, CSIR-Central Food Technological Research Institute, Mysuru, Karnataka, 570 020, India
| | - N Ramaiah
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India
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18
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Genome-scale revealing the central metabolic network of the fast growing methanotroph Methylomonas sp. ZR1. World J Microbiol Biotechnol 2021; 37:29. [PMID: 33452942 DOI: 10.1007/s11274-021-02995-7] [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: 11/05/2019] [Accepted: 01/05/2021] [Indexed: 10/22/2022]
Abstract
Methylomonas sp. ZR1 was an isolated new methanotrophs that could utilize methane and methanol growing fast and synthesizing value added compounds such as lycopene. In this study, the genomic study integrated with the comparative transcriptome analysis were taken to understanding the metabolic characteristic of ZR1 grown on methane and methanol at normal and high temperature regime. Complete Embden-Meyerhof-Parnas pathway (EMP), Entner-Doudoroff pathway (ED), Pentose Phosphate Pathway (PP) and Tricarboxy Acid Cycle (TCA) were found to be operated in ZR1. In addition, the energy saving ppi-dependent EMP enzyme, coupled with the complete and efficient central carbon metabolic network might be responsible for its fast growing nature. Transcript level analysis of the central carbon metabolism indicated that formaldehyde metabolism was a key nod that may be in charge of the carbon conversion efficiency (CCE) divergent of ZR1 grown on methanol and methane. Flexible nitrogen and carotene metabolism pattern were also investigated in ZR1. Nitrogenase genes in ZR1 were found to be highly expressed with methane even in the presence of sufficient nitrate. It appears that, higher lycopene production in ZR1 grown on methane might be attributed to the higher proportion of transcript level of C40 to C30 metabolic gene. Higher transcript level of exopolysaccharides metabolic gene and stress responding proteins indicated that ZR1 was confronted with severer growth stress with methanol than with methane. Additionally, lower transcript level of the TCA cycle, the dramatic high expression level of the nitric oxide reductase and stress responding protein, revealed the imbalance of the central carbon and nitrogen metabolic status, which would result in the worse growth of ZR1 with methanol at 30 °C.
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19
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Jawaharraj K, Shrestha N, Chilkoor G, Dhiman SS, Islam J, Gadhamshetty V. Valorization of methane from environmental engineering applications: A critical review. WATER RESEARCH 2020; 187:116400. [PMID: 32979578 DOI: 10.1016/j.watres.2020.116400] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/29/2020] [Accepted: 09/05/2020] [Indexed: 05/09/2023]
Abstract
Wastewater and waste management sectors alone account for 18% of the anthropogenic methane (CH4) emissions. This study presents a critical overview of methanotrophs ("methane oxidizing microorganisms") for valorizing typically discarded CH4 from environmental engineering applications, focusing on wastewater treatment plants. Methanotrophs can convert CH4 into valuable bioproducts including chemicals, biodiesel, DC electricity, polymers, and S-layers, all under ambient conditions. As discarded CH4 and its oxidation products can also be used as a carbon source in nitrification and annamox processes. Here we discuss modes of CH4 assimilation by methanotrophs in both natural and engineered systems. We also highlight the technical challenges and technological breakthroughs needed to enable targeted CH4 oxidation in wastewater treatment plants.
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Affiliation(s)
- Kalimuthu Jawaharraj
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States
| | - Namita Shrestha
- Civil and Environmental Engineering, Rose-Hulman Institute of Technology, Terre Haute 47803, IN, United States
| | - Govinda Chilkoor
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; 2-Dimensional Materials for Biofilm Engineering Science and Technology (2DBEST) Center, South Dakota School of Mines and Technology, Rapid City 57701, SD, United States
| | - Saurabh Sudha Dhiman
- BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States; Biological and Chemical Engineering, South Dakota School of Mines & Technology, Rapid City 57701, SD, United States
| | - Jamil Islam
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States
| | - Venkataramana Gadhamshetty
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States; 2-Dimensional Materials for Biofilm Engineering Science and Technology (2DBEST) Center, South Dakota School of Mines and Technology, Rapid City 57701, SD, United States.
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20
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Versantvoort W, Pol A, Jetten MSM, van Niftrik L, Reimann J, Kartal B, Op den Camp HJM. Multiheme hydroxylamine oxidoreductases produce NO during ammonia oxidation in methanotrophs. Proc Natl Acad Sci U S A 2020; 117:24459-24463. [PMID: 32913059 PMCID: PMC7533708 DOI: 10.1073/pnas.2011299117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Aerobic and nitrite-dependent methanotrophs make a living from oxidizing methane via methanol to carbon dioxide. In addition, these microorganisms cometabolize ammonia due to its structural similarities to methane. The first step in both of these processes is catalyzed by methane monooxygenase, which converts methane or ammonia into methanol or hydroxylamine, respectively. Methanotrophs use methanol for energy conservation, whereas toxic hydroxylamine is a potent inhibitor that needs to be rapidly removed. It is suggested that many methanotrophs encode a hydroxylamine oxidoreductase (mHAO) in their genome to remove hydroxylamine, although biochemical evidence for this is lacking. HAOs also play a crucial role in the metabolism of aerobic and anaerobic ammonia oxidizers by converting hydroxylamine to nitric oxide (NO). Here, we purified an HAO from the thermophilic verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV and characterized its kinetic properties. This mHAO possesses the characteristic P460 chromophore and is active up to at least 80 °C. It catalyzes the rapid oxidation of hydroxylamine to NO. In methanotrophs, mHAO efficiently removes hydroxylamine, which severely inhibits calcium-dependent, and as we show here, lanthanide-dependent methanol dehydrogenases, which are more prevalent in the environment. Our results indicate that mHAO allows methanotrophs to thrive under high ammonia concentrations in natural and engineered ecosystems, such as those observed in rice paddy fields, landfills, or volcanic mud pots, by preventing the accumulation of inhibitory hydroxylamine. Under oxic conditions, methanotrophs mainly oxidize ammonia to nitrite, whereas in hypoxic and anoxic environments reduction of both ammonia-derived nitrite and NO could lead to nitrous oxide (N2O) production.
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Affiliation(s)
- Wouter Versantvoort
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Arjan Pol
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Laura van Niftrik
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Joachim Reimann
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Boran Kartal
- Microbial Physiology Group, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Huub J M Op den Camp
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands
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21
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Changes in Methane Emission and Community Composition of Methane-Cycling Microorganisms Along an Elevation Gradient in the Dongting Lake Floodplain, China. ATMOSPHERE 2020. [DOI: 10.3390/atmos11090997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Methane (CH4) emission and environmental controls of CH4-cycling microorganisms are unclear in inland floodplains. Here, we examined soil CH4 emissions and the community composition of CH4-cycling microorganisms under three vegetation types—mudflat (MF, no vegetation cover), Carex meadow (CM, mainly Carex brevicuspis), and reed land (RL, mainly Miscanthus sacchariflorus)—from water-adjacent areas to higher-elevation land in the Dongting Lake floodplain, China. The results showed that CH4 emission is the highest in CM, while significant absorption was observed in the RL site. The abundance ratio of methanogen/methanotroph was the highest in CM, intermediate in MF, and lowest in RL. The Methanosarcinaceae family represented the dominant methanogens in the three sampling sites (41.32–75.25%). The genus Methylocystis (60.85%, type II methanotrophs) was dominant in CM, while Methylobacter and Methylosarcina (type I methanotrophs) were the dominant genera in MF (51.00%) and RL (50.24%), respectively. Structural equation model analysis showed that methanogen and methanotroph abundance were affected by water table depth, soil water content, and pH indirectly through soil organic content, total nitrogen, microbial biomass carbon, and microbial biomass nitrogen. These results indicated that the Dongting Lake floodplain may change from a CH4 source to a CH4 sink with vegetation succession with an increase in elevation, and the methanogen/methanotroph ratio can be used as a proxy for CH4 emission in wetland soils. The continuous increase in reed area combined with the decrease in Carex meadow may mitigate CH4 emission and enhance the CH4 sink function during the non-flood season in the Dongting Lake floodplain.
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22
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Stein LY. The Long-Term Relationship between Microbial Metabolism and Greenhouse Gases. Trends Microbiol 2020; 28:500-511. [DOI: 10.1016/j.tim.2020.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/09/2020] [Accepted: 01/16/2020] [Indexed: 11/26/2022]
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23
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Kuloyo O, Ruff SE, Cahill A, Connors L, Zorz JK, Hrabe de Angelis I, Nightingale M, Mayer B, Strous M. Methane oxidation and methylotroph population dynamics in groundwater mesocosms. Environ Microbiol 2020; 22:1222-1237. [PMID: 32017377 PMCID: PMC7187433 DOI: 10.1111/1462-2920.14929] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 01/25/2020] [Indexed: 01/21/2023]
Abstract
Extraction of natural gas from unconventional hydrocarbon reservoirs by hydraulic fracturing raises concerns about methane migration into groundwater. Microbial methane oxidation can be a significant methane sink. Here, we inoculated replicated, sand‐packed, continuous mesocosms with groundwater from a field methane release experiment. The mesocosms experienced thirty‐five weeks of dynamic methane, oxygen and nitrate concentrations. We determined concentrations and stable isotope signatures of methane, carbon dioxide and nitrate and monitored microbial community composition of suspended and attached biomass. Methane oxidation was strictly dependent on oxygen availability and led to enrichment of 13C in residual methane. Nitrate did not enhance methane oxidation under oxygen limitation. Methylotrophs persisted for weeks in the absence of methane, making them a powerful marker for active as well as past methane leaks. Thirty‐nine distinct populations of methylotrophic bacteria were observed. Methylotrophs mainly occurred attached to sediment particles. Abundances of methanotrophs and other methylotrophs were roughly similar across all samples, pointing at transfer of metabolites from the former to the latter. Two populations of Gracilibacteria (Candidate Phyla Radiation) displayed successive blooms, potentially triggered by a period of methane famine. This study will guide interpretation of future field studies and provides increased understanding of methylotroph ecophysiology.
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Affiliation(s)
- Olukayode Kuloyo
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.,Shell International Exploration and Production Inc, Westhollow Technology Center, Houston, TX, USA
| | - S Emil Ruff
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.,Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Aaron Cahill
- The Lyell Centre, Heriot Watt University, Edinburgh, United Kingdom
| | - Liam Connors
- Biomedical Sciences Department, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jackie K Zorz
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada
| | - Isabella Hrabe de Angelis
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.,Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | | | - Bernhard Mayer
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada
| | - Marc Strous
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada
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24
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Simultaneous Denitrification and Bio-Methanol Production for Sustainable Operation of Biogas Plants. SUSTAINABILITY 2019. [DOI: 10.3390/su11236658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study was conducted to secure the sustainability of biogas plants for generating resources from food waste (FW) leachates, which are prohibited from marine dumping and have been obligated to be completely treated on land since 2013 in South Korea. The aim of this study is to reduce the nitrogen load of the treatment process while producing bio-methanol using digested FW leachate diverted into wastewater treatment plants. By using biogas in conditions where methylobacter (M. marinus 88.2%) with strong tolerance to highly chlorinated FW leachate dominated, 3.82 mM of methanol production and 56.1% of total nitrogen (TN) removal were possible. Therefore, the proposed method can contribute to improving the treatment efficiency by accommodating twice the current carried-in FW leachate amount based on TN or by significantly reducing the nitrogen load in the subsequent wastewater treatment process. Moreover, the produced methanol can be an effective alternative for carbon source supply for denitrification in the subsequent process.
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25
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Wiseschart A, Mhuantong W, Tangphatsornruang S, Chantasingh D, Pootanakit K. Shotgun metagenomic sequencing from Manao-Pee cave, Thailand, reveals insight into the microbial community structure and its metabolic potential. BMC Microbiol 2019; 19:144. [PMID: 31248378 PMCID: PMC6598295 DOI: 10.1186/s12866-019-1521-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 06/19/2019] [Indexed: 12/21/2022] Open
Abstract
Background Due to the cave oligotrophic environment, this habitat presents a challenge for microorganisms to colonize and thrive. However, it has been well documented that microorganisms play important roles in cave development. Survival of microbes in this unique habitat likely involves a broad range of adaptive capabilities. Recently, cave microbiomes all over the world are of great scientific interest. However, the majority of investigations focused mostly on small subunit ribosomal RNA (16S rRNA) gene, leaving the ecological role of the microbial community largely unknown. Here, we are particularly interested in exploring the taxonomic composition and metabolic potential of microorganisms in soil from Manao-Pee cave, a subterranean limestone cave in the western part of Thailand, by using high-throughput shotgun metagenomic sequencing. Results From taxonomic composition analysis using ribosomal RNA genes (rRNA), the results confirmed that Actinobacteria (51.2%) and Gammaproteobacteria (24.4%) were the dominant bacterial groups in the cave soil community. Metabolic potential analysis, based on six functional modules of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, revealed that functional genes involved in microbial metabolisms are highly represented in this community (40.6%). To better understand how microbes thrive under unfavorable cave condition, we focused on microbial energy metabolism. The results showed that microbial genes involved in oxidative phosphorylation were the most dominant (28.8%) in Manao-Pee cave, and were followed by methane metabolism (20.5%), carbon fixation (16.0%), nitrogen metabolism (14.7%), and sulfur metabolism (6.3%). In addition, microbial genes involved in xenobiotic biodegradation (26 pathways) and in production of secondary metabolites (27 pathways) were also identified. Conclusion In addition to providing information on microbial diversity, we also gained insights into microbial adaptations and survival strategies under cave conditions. Based on rRNA genes, the results revealed that bacteria belonging to the Actinobacteria and Gammaproteobacteria were the most abundant in this community. From metabolic potential analysis, energy and nutrient sources that sustain diverse microbial population in this community might be atmospheric gases (methane, carbon dioxide, nitrogen), inorganic sulfur, and xenobiotic compounds. In addition, the presence of biosynthetic pathways of secondary metabolites suggested that they might play important ecological roles in the cave microbiome. Electronic supplementary material The online version of this article (10.1186/s12866-019-1521-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Apirak Wiseschart
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Phuttamonthon 4 Rd, Salaya, Nakhon Pathom, 73170, Thailand
| | - Wuttichai Mhuantong
- National Center for Genetic Engineering and Biotechnology (BIOTEC), 133 Thailand Science Park, Paholyothin Rd, Klong 1, Klongluang, Pathumthani, 12120, Thailand
| | - Sithichoke Tangphatsornruang
- National Center for Genetic Engineering and Biotechnology (BIOTEC), 133 Thailand Science Park, Paholyothin Rd, Klong 1, Klongluang, Pathumthani, 12120, Thailand
| | - Duriya Chantasingh
- National Center for Genetic Engineering and Biotechnology (BIOTEC), 133 Thailand Science Park, Paholyothin Rd, Klong 1, Klongluang, Pathumthani, 12120, Thailand
| | - Kusol Pootanakit
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Phuttamonthon 4 Rd, Salaya, Nakhon Pathom, 73170, Thailand.
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26
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AlSayed A, Fergala A, Eldyasti A. Enhancement of the cultivation process conditions of mixed culture methanotrophic Proteobacteria phylum enriched from waste activated sludge as the first step for value added recovery process. J Biosci Bioeng 2019; 127:602-608. [DOI: 10.1016/j.jbiosc.2018.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 10/08/2018] [Accepted: 10/24/2018] [Indexed: 12/14/2022]
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27
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Rago L, Zecchin S, Villa F, Goglio A, Corsini A, Cavalca L, Schievano A. Bioelectrochemical Nitrogen fixation (e-BNF): Electro-stimulation of enriched biofilm communities drives autotrophic nitrogen and carbon fixation. Bioelectrochemistry 2019; 125:105-115. [DOI: 10.1016/j.bioelechem.2018.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/11/2018] [Accepted: 10/12/2018] [Indexed: 10/28/2022]
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28
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La H, Hettiaratchi JPA, Achari G, Dunfield PF. Biofiltration of methane. BIORESOURCE TECHNOLOGY 2018; 268:759-772. [PMID: 30064899 DOI: 10.1016/j.biortech.2018.07.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 06/08/2023]
Abstract
The on-going annual increase in global methane (CH4) emissions can be largely attributed to anthropogenic activities. However, as more than half of these emissions are diffuse and possess a concentration less than 3% (v/v), physical-chemical treatments are inefficient as an abatement technology. In this regard, biotechnologies, such as biofiltration using methane-oxidizing bacteria, or methanotrophs, are a cost-effective and efficient means of combating diffuse CH4 emissions. In this review, a number of abiotic factors including temperature, pH, water content, packing material, empty-bed residence time, inlet gas flow rate, CH4 concentration, as well biotic factors, such as biomass development, are reviewed based on empirical findings on CH4 biofiltration studies that have been performed in the last decades.
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Affiliation(s)
- Helen La
- Department of Civil Engineering, Center for Environmental Engineering Research and Education (CEERE), University of Calgary, 2500 University Drive, NW, Calgary, Alberta T2N 1N4 Canada
| | - J Patrick A Hettiaratchi
- Department of Civil Engineering, Center for Environmental Engineering Research and Education (CEERE), University of Calgary, 2500 University Drive, NW, Calgary, Alberta T2N 1N4 Canada
| | - Gopal Achari
- Department of Civil Engineering, Center for Environmental Engineering Research and Education (CEERE), University of Calgary, 2500 University Drive, NW, Calgary, Alberta T2N 1N4 Canada.
| | - Peter F Dunfield
- Department of Biological Sciences, University of Calgary, 2500 University Drive, NW, Calgary, Alberta T2N 1N4 Canada
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29
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Bio-Methanol Production Using Treated Domestic Wastewater with Mixed Methanotroph Species and Anaerobic Digester Biogas. WATER 2018. [DOI: 10.3390/w10101414] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The development of cost-effective methods, which generate minimal chemical wastewater, for methanol production is an important research goal. In this study, treated wastewater (TWW) was utilized as a culture solution for methanol production by mixed methanotroph species as an alternative to media prepared from commercial or chemical agents, e.g., nitrate mineral salts medium. Furthermore, a realistic alternative for producing methanol in wastewater treatment plants using biogas from anaerobic digestion was proposed. By culturing mixed methanotroph species with nitrate and phosphate-supplemented TWW in municipal wastewater treatment plants, this study demonstrates, for the first time, the application of biogas generated from the sludge digester of municipal wastewater treatment plants. NaCl alone inhibited methanol dehydrogenase and the addition of 40 mM formate as an electron donor increased methanol production to 6.35 mM. These results confirmed that this practical energy production method could enable cost-effective methanol production. As such, methanol produced in wastewater treatment plants can be used as an eco-friendly energy and carbon source for biological denitrification, which can be an alternative to reducing the expenses required for the waste water treatment process.
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30
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Modin O. A mathematical model of aerobic methane oxidation coupled to denitrification. ENVIRONMENTAL TECHNOLOGY 2018; 39:1217-1225. [PMID: 28443363 DOI: 10.1080/09593330.2017.1323961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 04/21/2017] [Indexed: 06/07/2023]
Abstract
Aerobic methanotrophic bacteria use methane as their only source of energy and carbon. They release organic compounds that can serve as electron donors for co-existing denitrifiers. This interaction between methanotrophs and denitrifiers is known to contribute to nitrogen losses in natural environments and has also been exploited by researchers for denitrification of nitrate-contaminated wastewater. The purpose of this study was to develop a mathematical model describing aerobic methane oxidation coupled to denitrification in suspended-growth reactors. The model considered the activities of three microbial groups: aerobic methanotrophs, facultative methylotrophs, and facultative heterotrophs. The model was tested against data from the scientific literature and used to explore the effects of the oxygen mass transfer coefficient, the solids retention time, and the fraction methane in the feed gas on nitrate removal. The fraction of methane in the feed gas was found to be critical for the nitrate removal rate. A value of about 15% in air was optimal. A lower methane fraction led to excess oxygen, which was detrimental for denitrification. A higher fraction led to oxygen-limitation, which restricted the growth rate of methanotrophs in the reactor.
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Affiliation(s)
- Oskar Modin
- a Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , Gothenburg , Sweden
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31
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Schnyder E, Bodelier PLE, Hartmann M, Henneberger R, Niklaus PA. Positive diversity-functioning relationships in model communities of methanotrophic bacteria. Ecology 2018; 99:714-723. [PMID: 29323701 DOI: 10.1002/ecy.2138] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 11/01/2017] [Accepted: 12/20/2017] [Indexed: 11/11/2022]
Abstract
Biodiversity enhances ecosystem functions such as biomass production and nutrient cycling. Although the majority of the terrestrial biodiversity is hidden in soils, very little is known about the importance of the diversity of microbial communities for soil functioning. Here, we tested effects of biodiversity on the functioning of methanotrophs, a specialized group of soil bacteria that plays a key role in mediating greenhouse gas emissions from soils. Using pure strains of methanotrophic bacteria, we assembled artificial communities of different diversity levels, with which we inoculated sterile soil microcosms. To assess the functioning of these communities, we measured methane oxidation by gas chromatography throughout the experiment and determined changes in community composition and community size at several time points by quantitative PCR and sequencing. We demonstrate that microbial diversity had a positive overyielding effect on methane oxidation, in particular at the beginning of the experiment. This higher assimilation of CH4 at high diversity translated into increased growth and significantly larger communities towards the end of the study. The overyielding of mixtures with respect to CH4 consumption and community size were positively correlated. The temporal CH4 consumption profiles of strain monocultures differed, raising the possibility that temporal complementarity of component strains drove the observed community-level strain richness effects; however, the community niche metric we derived from the temporal activity profiles did not explain the observed strain richness effect. The strain richness effect also was unrelated to both the phylogenetic and functional trait diversity of mixed communities. Overall, our results suggest that positive biodiversity-ecosystem-function relationships show similar patterns across different scales and may be widespread in nature. Additionally, biodiversity is probably also important in natural methanotrophic communities for the ecosystem function methane oxidation. Therefore, maintaining soil conditions that support a high diversity of methanotrophs may help to reduce the emission of the greenhouse gas methane.
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Affiliation(s)
- Elvira Schnyder
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands
| | - Martin Hartmann
- Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
| | - Ruth Henneberger
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätstrasse 16, CH-8092, Zurich, Switzerland
| | - Pascal A Niklaus
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.,University of Zurich Research Priority Program Global Change and Biodiversity, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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32
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Weisener C, Lee J, Chaganti SR, Reid T, Falk N, Drouillard K. Investigating sources and sinks of N 2O expression from freshwater microbial communities in urban watershed sediments. CHEMOSPHERE 2017; 188:697-705. [PMID: 28934707 DOI: 10.1016/j.chemosphere.2017.09.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/06/2017] [Accepted: 09/09/2017] [Indexed: 06/07/2023]
Abstract
Wastewater treatment plants (WWTPs) serve as point-source inputs for a variety of nutrients often dominated by nitrogenous compounds as a result of anthropogenic influence. These effluents can impact biogeochemical cycles in freshwater estuaries, influencing microbial communities in both the water and sediment compartments. To assess the impact of point source nutrients, a transect of sediment and pore water samples were collected from 4 locations in the Little River Sub-watershed including locations above and below the Little River Pollution Control Plant (LRPCP). Variation in chemistry and microbial community/gene expression revealed significant influences of the effluent discharge on the adjacent sediments. Phosphorus and sulfur showed high concentrations within plume sediments compared to the reference sediments while nitrate concentrations were low. Increased abundance of denitrifiers Dechloromonas, Dok59 and Thermomonas correlating with increased expression of nitrous-oxide reductase suggests a conversion of N2O to N2 within the LRPCP effluent sediments. This study provides valuable insight into the gene regulation of microbes involved in N metabolism (denitrification, nitrification, and nitrite reduction to ammonia) within the sediment compartment influenced by wastewater effluent.
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Affiliation(s)
- Christopher Weisener
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada.
| | - Jumin Lee
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada; Earth Science Department, Western University, London, Ontario, Canada
| | - Subba Rao Chaganti
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada
| | - Thomas Reid
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada
| | - Nick Falk
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada
| | - Ken Drouillard
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada
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33
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A novel methanotroph in the genus Methylomonas that contains a distinct clade of soluble methane monooxygenase. J Microbiol 2017; 55:775-782. [DOI: 10.1007/s12275-017-7317-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/25/2017] [Accepted: 08/31/2017] [Indexed: 10/18/2022]
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34
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Illumina sequencing of bacterial 16S rDNA and 16S rRNA reveals seasonal and species-specific variation in bacterial communities in four moss species. Appl Microbiol Biotechnol 2017; 101:6739-6753. [DOI: 10.1007/s00253-017-8391-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/14/2017] [Accepted: 06/15/2017] [Indexed: 11/27/2022]
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35
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Crenothrix are major methane consumers in stratified lakes. ISME JOURNAL 2017; 11:2124-2140. [PMID: 28585934 PMCID: PMC5563964 DOI: 10.1038/ismej.2017.77] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 04/13/2017] [Accepted: 04/21/2017] [Indexed: 01/29/2023]
Abstract
Methane-oxidizing bacteria represent a major biological sink for methane and are thus Earth’s natural protection against this potent greenhouse gas. Here we show that in two stratified freshwater lakes a substantial part of upward-diffusing methane was oxidized by filamentous gamma-proteobacteria related to Crenothrix polyspora. These filamentous bacteria have been known as contaminants of drinking water supplies since 1870, but their role in the environmental methane removal has remained unclear. While oxidizing methane, these organisms were assigned an ‘unusual’ methane monooxygenase (MMO), which was only distantly related to ‘classical’ MMO of gamma-proteobacterial methanotrophs. We now correct this assignment and show that Crenothrix encode a typical gamma-proteobacterial PmoA. Stable isotope labeling in combination swith single-cell imaging mass spectrometry revealed methane-dependent growth of the lacustrine Crenothrix with oxygen as well as under oxygen-deficient conditions. Crenothrix genomes encoded pathways for the respiration of oxygen as well as for the reduction of nitrate to N2O. The observed abundance and planktonic growth of Crenothrix suggest that these methanotrophs can act as a relevant biological sink for methane in stratified lakes and should be considered in the context of environmental removal of methane.
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36
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Te SH, Tan BF, Thompson JR, Gin KYH. Relationship of Microbiota and Cyanobacterial Secondary Metabolites in Planktothricoides-Dominated Bloom. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4199-4209. [PMID: 28345890 DOI: 10.1021/acs.est.6b05767] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The identification of phytoplankton species and microbial biodiversity is necessary to assess water ecosystem health and the quality of water resources. We investigated the short-term (2 days) vertical and diel variations in bacterial community structure and microbially derived secondary metabolites during a cyanobacterial bloom that emerged in a highly urbanized tropical reservoir. The waterbody was largely dominated by the cyanobacteria Planktothricoides spp., together with the Synechococcus, Pseudanabaena, Prochlorothrix, and Limnothrix. Spatial differences (i.e., water depth) rather than temporal differences (i.e., day versus night) better-explained the short-term variability in water quality parameters and bacterial community composition. Difference in bacterial structure suggested a resource-driven distribution pattern for the community. We found that the freshwater bacterial community associated with cyanobacterial blooms is largely conserved at the phylum level, with Proteobacteria (β-proteobateria), Bacteroidetes, and Actinobacteria as the main taxa despite the cyanobacterial species present and geographical (Asia, Europe, Australia, and North America) or climatic distinctions. Through multivariate statistical analyses of the bacterial community, environmental parameters, and secondary metabolite concentrations, we observed positive relationships between the occurrences of cyanobacterial groups and off-flavor compounds (2-methyisoborneol and β-ionone), suggesting a cyanobacterial origin. This study demonstrates the potential of 16S rRNA gene amplicon sequencing as a supporting tool in algal bloom monitoring or water-resource management.
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Affiliation(s)
- Shu Harn Te
- NUS Environmental Research Institute, National University of Singapore , 5A Engineering Drive 1, No. 02-01 T-Lab Building, Singapore 117411
| | - Boon Fei Tan
- Centre for Environmental Sensing and Modelling, Singapore-MIT Alliance for Research and Technology Centre , 1 CREATE Way, #09-03 CREATE Tower, Singapore 138602
| | - Janelle R Thompson
- Centre for Environmental Sensing and Modelling, Singapore-MIT Alliance for Research and Technology Centre , 1 CREATE Way, #09-03 CREATE Tower, Singapore 138602
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Karina Yew-Hoong Gin
- NUS Environmental Research Institute, National University of Singapore , 5A Engineering Drive 1, No. 02-01 T-Lab Building, Singapore 117411
- Department of Civil and Environmental Engineering, National University of Singapore , 1 Engineering Drive 2, E1A 07-03, Singapore 117576
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37
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Vekeman B, Speth D, Wille J, Cremers G, De Vos P, Op den Camp HJM, Heylen K. Genome Characteristics of Two Novel Type I Methanotrophs Enriched from North Sea Sediments Containing Exclusively a Lanthanide-Dependent XoxF5-Type Methanol Dehydrogenase. MICROBIAL ECOLOGY 2016; 72:503-509. [PMID: 27457652 DOI: 10.1007/s00248-016-0808-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/22/2016] [Indexed: 06/06/2023]
Abstract
Microbial methane oxidizers play a crucial role in the oxidation of methane in marine ecosystems, as such preventing the escape of excessive methane to the atmosphere. Despite the important role of methanotrophs in marine ecosystems, only a limited number of isolates are described, with only four genomes available. Here, we report on two genomes of gammaproteobacterial methanotroph cultures, affiliated with the deep-sea cluster 2, obtained from North Sea sediment. Initial enrichments using methane as sole source of carbon and energy and mimicking the in situ conditions followed by serial subcultivations and multiple extinction culturing events over a period of 3 years resulted in a highly enriched culture. The draft genomes of the methane oxidizer in both cultures showed the presence of genes typically found in type I methanotrophs, including genes encoding particulate methane monooxygenase (pmoCAB), genes for tetrahydromethanopterin (H4MPT)- and tetrahydrofolate (H4F)-dependent C1-transfer pathways, and genes of the ribulose monophosphate (RuMP) pathway. The most distinctive feature, when compared to other available gammaproteobacterial genomes, is the absence of a calcium-dependent methanol dehydrogenase. Both genomes reported here only have a xoxF gene encoding a lanthanide-dependent XoxF5-type methanol dehydrogenase. Thus, these genomes offer novel insight in the genomic landscape of uncultured diversity of marine methanotrophs.
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Affiliation(s)
- Bram Vekeman
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, 9000, Ghent, Belgium.
| | - Daan Speth
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Jasper Wille
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Geert Cremers
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Paul De Vos
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Huub J M Op den Camp
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Kim Heylen
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, 9000, Ghent, Belgium
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38
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Vekeman B, Kerckhof FM, Cremers G, de Vos P, Vandamme P, Boon N, Op den Camp HJM, Heylen K. New Methyloceanibacter diversity from North Sea sediments includes methanotroph containing solely the soluble methane monooxygenase. Environ Microbiol 2016; 18:4523-4536. [PMID: 27501305 DOI: 10.1111/1462-2920.13485] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/04/2016] [Indexed: 12/14/2022]
Abstract
Marine methylotrophs play a key role in the global carbon cycle by metabolizing reduced one-carbon compounds that are found in high concentrations in marine environments. Genome, physiology and diversity studies have been greatly facilitated by the numerous model organisms brought into culture. However, the availability of marine representatives remains poor. Here, we report the isolation of four novel species from North Sea sediment enrichments closely related to the Alphaproteobacterium Methyloceanibacter caenitepidi. Each of the newly isolated Methyloceanibacter species exhibited a clear genome sequence divergence which was reflected in physiological differences. Notably one strain R-67174 was capable of oxidizing methane as sole source of carbon and energy using solely a soluble methane monooxygenase and represents the first marine Alphaproteobacterial methanotroph brought into culture. Differences in maximum cell density of >1.5 orders of magnitude were observed. Furthermore, three strains were capable of producing nitrous oxide from nitrate. Together, these findings highlight the metabolic and physiologic variability within closely related Methyloceanibacter species and provide a new understanding of the physiological basis of marine methylotrophy.
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Affiliation(s)
- Bram Vekeman
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, Gent, 9000, Belgium
| | - Frederiek-Maarten Kerckhof
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent, 9000, Belgium
| | - Geert Cremers
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, AJ Nijmegen, 6525, The Netherlands
| | - Paul de Vos
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, Gent, 9000, Belgium
| | - Peter Vandamme
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, Gent, 9000, Belgium.,BCCM/LMG Bacteria Collection, Ghent University, Karel Lodewijck Ledeganckstraat 35, Gent, 9000, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent, 9000, Belgium
| | - Huub J M Op den Camp
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, AJ Nijmegen, 6525, The Netherlands
| | - Kim Heylen
- Department of Biochemistry and Microbiology, Laboratory of Microbiology (LM-UGent), Ghent University, Karel Lodewijck Ledeganckstraat 35, Gent, 9000, Belgium
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39
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Ho A, Angel R, Veraart AJ, Daebeler A, Jia Z, Kim SY, Kerckhof FM, Boon N, Bodelier PLE. Biotic Interactions in Microbial Communities as Modulators of Biogeochemical Processes: Methanotrophy as a Model System. Front Microbiol 2016; 7:1285. [PMID: 27602021 PMCID: PMC4993757 DOI: 10.3389/fmicb.2016.01285] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/04/2016] [Indexed: 11/13/2022] Open
Abstract
Microbial interaction is an integral component of microbial ecology studies, yet the role, extent, and relevance of microbial interaction in community functioning remains unclear, particularly in the context of global biogeochemical cycles. While many studies have shed light on the physico-chemical cues affecting specific processes, (micro)biotic controls and interactions potentially steering microbial communities leading to altered functioning are less known. Yet, recent accumulating evidence suggests that the concerted actions of a community can be significantly different from the combined effects of individual microorganisms, giving rise to emergent properties. Here, we exemplify the importance of microbial interaction for ecosystem processes by analysis of a reasonably well-understood microbial guild, namely, aerobic methane-oxidizing bacteria (MOB). We reviewed the literature which provided compelling evidence for the relevance of microbial interaction in modulating methane oxidation. Support for microbial associations within methane-fed communities is sought by a re-analysis of literature data derived from stable isotope probing studies of various complex environmental settings. Putative positive interactions between active MOB and other microbes were assessed by a correlation network-based analysis with datasets covering diverse environments where closely interacting members of a consortium can potentially alter the methane oxidation activity. Although, methanotrophy is used as a model system, the fundamentals of our postulations may be applicable to other microbial guilds mediating other biogeochemical processes.
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Affiliation(s)
- Adrian Ho
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Roey Angel
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network Chemistry meets Microbiology, University of Vienna Vienna, Austria
| | - Annelies J Veraart
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Anne Daebeler
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network Chemistry meets Microbiology, University of Vienna Vienna, Austria
| | - Zhongjun Jia
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences Nanjing, China
| | - Sang Yoon Kim
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Frederiek-Maarten Kerckhof
- Center for Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University Ghent, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University Ghent, Belgium
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
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40
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Draft Genome Sequences of Eight Obligate Methane Oxidizers Occupying Distinct Niches Based on Their Nitrogen Metabolism. GENOME ANNOUNCEMENTS 2016; 4:4/4/e00421-16. [PMID: 27491982 PMCID: PMC4974303 DOI: 10.1128/genomea.00421-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The genome sequences of Methylomonas methanica (NCIMB 11130T, R-45363, and R-45371), Methylomonas koyamae (R-45378, R-45383, and R-49807), Methylomonas lenta (R-45370), and Methylosinus sp. (R-45379) were obtained. These aerobic methanotrophs were isolated from terrestrial ecosystems, and their distinct phenotypes related to nitrogen assimilation and dissimilation were previously reported.
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41
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Walkiewicz A, Bulak P, Brzezińska M, Wnuk E, Bieganowski A. Methane oxidation in heavy metal contaminated Mollic Gleysol under oxic and hypoxic conditions. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 213:403-411. [PMID: 26946175 DOI: 10.1016/j.envpol.2016.02.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 02/23/2016] [Accepted: 02/24/2016] [Indexed: 05/26/2023]
Abstract
Soils are the largest terrestrial sink for methane (CH4). However, heavy metals may exert toxicity to soil microorganisms, including methanotrophic bacteria. We tested the effect of lead (Pb), zinc (Zn) and nickel (Ni) on CH4 oxidation (1% v/v) and dehydrogenase activity, an index of the activity of the total soil microbial community in Mollic Gleysol soil in oxic and hypoxic conditions (oxia and hypoxia, 20% and 10% v/v O2, respectively). Metals were added in doses corresponding to the amounts permitted of Pb, Zn, Ni in agricultural soils (60, 120, 35 mg kg(-1), respectively), and half and double of these doses. Relatively low metal contents and O2 status reflect the conditions of most agricultural soils of temperate regions. Methane consumption showed high tolerance to heavy metals. The effect of O2 status was stronger than that of metals. CH4 consumption was enhanced under hypoxia, where both the start and the completion of the control and contaminated treatment were faster than under oxic conditions. Dehydrogenase activity, showed higher sensitivity to the contamination (except for low Ni dose), with a stronger effect of heavy metals, than that of the O2 status.
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Affiliation(s)
- A Walkiewicz
- Institute of Agrophysics, Polish Academy of Sciences, Department of Natural Environment Biogeochemistry, Doświadczalna 4, 20-290, Lublin, Poland.
| | - P Bulak
- Institute of Agrophysics, Polish Academy of Sciences, Department of Natural Environment Biogeochemistry, Doświadczalna 4, 20-290, Lublin, Poland
| | - M Brzezińska
- Institute of Agrophysics, Polish Academy of Sciences, Department of Natural Environment Biogeochemistry, Doświadczalna 4, 20-290, Lublin, Poland
| | - E Wnuk
- Institute of Agrophysics, Polish Academy of Sciences, Department of Natural Environment Biogeochemistry, Doświadczalna 4, 20-290, Lublin, Poland
| | - A Bieganowski
- Institute of Agrophysics, Polish Academy of Sciences, Department of Natural Environment Biogeochemistry, Doświadczalna 4, 20-290, Lublin, Poland
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42
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Sun Y, De Vos P, Heylen K. Nitrous oxide emission by the non-denitrifying, nitrate ammonifier Bacillus licheniformis. BMC Genomics 2016; 17:68. [PMID: 26786044 PMCID: PMC4719734 DOI: 10.1186/s12864-016-2382-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/06/2016] [Indexed: 02/08/2023] Open
Abstract
Background Firmicutes have the capacity to remove excess nitrate from the environment via either denitrification, dissimilatory nitrate reduction to ammonium or both. The recent renewed interest in their nitrogen metabolism has revealed many interesting features, the most striking being their wide variety of dissimilatory nitrate reduction pathways. In the present study, nitrous oxide production from Bacillus licheniformis, a ubiquitous Gram-positive, spore-forming species with many industrial applications, is investigated. Results B. licheniformis has long been considered a denitrifier but physiological experiments on three different strains demonstrated that nitrous oxide is not produced from nitrate in stoichiometric amounts, rather ammonium is the most important end-product, produced during fermentation. Significant strain dependency in end-product ratios, attributed to nitrite and ammonium, and medium dependency in nitrous oxide production were also observed. Genome analyses confirmed the lack of a nitrite reductase to nitric oxide, the key enzyme of denitrification. Based on the gene inventory and building on knowledge from other non-denitrifying nitrous oxide emitters, hypothetical pathways for nitrous oxide production, involving NarG, NirB, qNor and Hmp, are proposed. In addition, all publically available genomes of B. licheniformis demonstrated similar gene inventories, with specific duplications of the nar operon, narK and hmp genes as well as NarG phylogeny supporting the evolutionary separation of previously described distinct BALI1 and BALI2 lineages. Conclusions Using physiological and genomic data we have demonstrated that the common soil bacterium B. licheniformis does not denitrify but is capable of fermentative dissimilatory nitrate/nitrite reduction to ammonium (DNRA) with concomitant production of N2O. Considering its ubiquitous nature and non-fastidious growth in the lab, B. licheniformis is a suitable candidate for further exploration of the actual mechanism of N2O production in DNRA bacteria and its relevance in situ. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2382-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yihua Sun
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
| | - Paul De Vos
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium. .,BCCM/LMG Bacteria Collection, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
| | - Kim Heylen
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
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43
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Schmidt ML, White JD, Denef VJ. Phylogenetic conservation of freshwater lake habitat preference varies between abundant bacterioplankton phyla. Environ Microbiol 2016; 18:1212-26. [DOI: 10.1111/1462-2920.13143] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 12/01/2022]
Affiliation(s)
- Marian L. Schmidt
- Department of Ecology and Evolutionary Biology; University of Michigan; Ann Arbor MI 48109 USA
| | - Jeffrey D. White
- Department of Biology; Framingham State University; Framingham MA 01701 USA
| | - Vincent J. Denef
- Department of Ecology and Evolutionary Biology; University of Michigan; Ann Arbor MI 48109 USA
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44
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Myung J, Wang Z, Yuan T, Zhang P, Van Nostrand JD, Zhou J, Criddle CS. Production of Nitrous Oxide from Nitrite in Stable Type II Methanotrophic Enrichments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10969-10975. [PMID: 26301949 DOI: 10.1021/acs.est.5b03385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The coupled aerobic-anoxic nitrous decomposition operation is a new process for wastewater treatment that removes nitrogen from wastewater and recovers energy from the nitrogen in three steps: (1) NH4(+) oxidation to NO2(-), (2) NO2(-) reduction to N2O, and (3) N2O conversion to N2 with energy production. Here, we demonstrate that type II methanotrophic enrichments can mediate step two by coupling oxidation of poly(3-hydroxybutyrate) (P3HB) to NO2(-) reduction. Enrichments grown with NH4(+) and NO2(-) were subject to alternating 48-h aerobic and anoxic periods, in which CH4 and NO2(-) were added together in a "coupled" mode of operation or separately in a "decoupled mode". Community structure was stable in both modes and dominated by Methylocystis. In the coupled mode, production of P3HB and N2O was low. In the decoupled mode, significant P3HB was produced, and oxidation of P3HB drove reduction of NO2(-) to N2O with ∼ 70% conversion for >30 cycles (120 d). In batch tests of wasted cells from the decoupled mode, N2O production rates increased at low O2 or high NO2(-) levels. The results are significant for the development of engineered processes that remove nitrogen from wastewater and for understanding of conditions that favor environmental production of N2O.
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Affiliation(s)
- Jaewook Myung
- Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States
| | - Zhiyue Wang
- Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States
| | - Tong Yuan
- Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma , Norman, Oklahoma 73019, United States
| | - Ping Zhang
- Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma , Norman, Oklahoma 73019, United States
| | - Joy D Van Nostrand
- Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma , Norman, Oklahoma 73019, United States
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma , Norman, Oklahoma 73019, United States
| | - Craig S Criddle
- Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States
- Woods Institute for the Environment, Stanford, California 94305, United States
- William and Cloy Codiga Resource Recovery Center, Stanford, California 94305, United States
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45
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Kits KD, Klotz MG, Stein LY. Methane oxidation coupled to nitrate reduction under hypoxia by the Gammaproteobacterium Methylomonas denitrificans, sp. nov. type strain FJG1. Environ Microbiol 2015; 17:3219-32. [PMID: 25580993 DOI: 10.1111/1462-2920.12772] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/31/2014] [Indexed: 02/02/2023]
Abstract
Obligate methanotrophs belonging to the Phyla Proteobacteria and Verrucomicrobia require oxygen for respiration and methane oxidation; nevertheless, aerobic methanotrophs are abundant and active in low oxygen environments. While genomes of some aerobic methanotrophs encode putative nitrogen oxide reductases, it is not understood whether these metabolic modules are used for NOx detoxification, denitrification or other purposes. Here we demonstrate using microsensor measurements that a gammaproteobacterial methanotroph Methylomonas denitrificans sp. nov. strain FJG1(T) couples methane oxidation to nitrate reduction under oxygen limitation, releasing nitrous oxide as a terminal product. Illumina RNA-Seq data revealed differential expression of genes encoding a denitrification pathway previously unknown to methanotrophs as well as the pxmABC operon in M. denitrificans sp. nov. strain FJG1(T) in response to hypoxia. Physiological and transcriptome data indicate that genetic inventory encoding the denitrification pathway is upregulated only upon availability of nitrate under oxygen limitation. In addition, quantitation of ATP levels demonstrates that the denitrification pathway employs inventory such as nitrate reductase NarGH serving M. denitrificans sp. nov. strain FJG1(T) to conserve energy during oxygen limitation. This study unravelled an unexpected metabolic flexibility of aerobic methanotrophs, thereby assigning these bacteria a new role at the metabolic intersection of the carbon and nitrogen cycles.
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Affiliation(s)
- K Dimitri Kits
- Department of Biological Sciences, University of Alberta, CW405, Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
| | - Martin G Klotz
- Department of Biological Sciences, University of North Carolina, 9201 University City Boulevard, Charlotte, NC, 28223, USA.,Institute of Marine Microbes and Ecospheres and State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361005, China
| | - Lisa Y Stein
- Department of Biological Sciences, University of Alberta, CW405, Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
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46
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Shidhi PR, Suravajhala P, Nayeema A, Nair AS, Singh S, Dhar PK. Making novel proteins from pseudogenes. Bioinformatics 2015; 31:33-9. [PMID: 25236460 DOI: 10.1093/bioinformatics/btu615] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
MOTIVATION Recently, we made synthetic proteins from non-coding DNA of Escherichia coli. Encouraged by this, we asked: can we artificially express pseudogenes into novel and functional proteins? What kind of structures would be generated? Would these proteins be stable? How would the organism respond to the artificial reactivation of pseudogenes? RESULTS To answer these questions, we studied 16 full-length protein equivalents of pseudogenes. The sequence-based predictions indicated interesting molecular and cellular functional roles for pseudogene-derived proteins. Most of the proteins were predicted to be involved in the amino acid biosynthesis, energy metabolism, purines and pyrimidine biosynthesis, central intermediary metabolism, transport and binding. Interestingly, many of the pseudogene-derived proteins were predicted to be enzymes. Furthermore, proteins showed strong evidence of stable tertiary structures. The prediction scores for structure, function and stability were found to be favorable in most of the cases. IMPACT To our best knowledge, this is the first such report that predicts the possibility of making functional and stable proteins from pseudogenes. In future, it would be interesting to experimentally synthesize and validate these predictions.
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Affiliation(s)
- P R Shidhi
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
| | - Prashanth Suravajhala
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
| | - Aysha Nayeema
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
| | - Achuthsankar S Nair
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
| | - Shailja Singh
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
| | - Pawan K Dhar
- Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India Department of Computational Biology and Bioinformatics, University of Kerala, Kariyavattom, Trivandrum- 695 581, India, Bioinformatics.Org, 28 Pope Street, Hudson, MA 01749, USA, Bioclues.org, India, Bioclues.org, Denmark, National College, University of Kerala, Trivandrum- 695 009, Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh- 201 314, and Centre for Systems and Synthetic Biology, University of Kerala, Kariyavattom, Trivandrum- 695 581, India
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