1
|
Decembrino D, Cannella D. The thin line between monooxygenases and peroxygenases. P450s, UPOs, MMOs, and LPMOs: A brick to bridge fields of expertise. Biotechnol Adv 2024; 72:108321. [PMID: 38336187 DOI: 10.1016/j.biotechadv.2024.108321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/04/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Many scientific fields, although driven by similar purposes and dealing with similar technologies, often appear so isolated and far from each other that even the vocabularies to describe the very same phenomenon might differ. Concerning the vast field of biocatalysis, a special role is played by those redox enzymes that employ oxygen-based chemistry to unlock transformations otherwise possible only with metal-based catalysts. As such, greener chemical synthesis methods and environmentally-driven biotechnological approaches were enabled over the last decades by the use of several enzymes and ultimately resulted in the first industrial applications. Among what can be called today the environmental biorefinery sector, biomass transformation, greenhouse gas reduction, bio-gas/fuels production, bioremediation, as well as bulk or fine chemicals and even pharmaceuticals manufacturing are all examples of fields in which successful prototypes have been demonstrated employing redox enzymes. In this review we decided to focus on the most prominent enzymes (MMOs, LPMO, P450 and UPO) capable of overcoming the ∼100 kcal mol-1 barrier of inactivated CH bonds for the oxyfunctionalization of organic compounds. Harnessing the enormous potential that lies within these enzymes is of extreme value to develop sustainable industrial schemes and it is still deeply coveted by many within the aforementioned fields of application. Hence, the ambitious scope of this account is to bridge the current cutting-edge knowledge gathered upon each enzyme. By creating a broad comparison, scientists belonging to the different fields may find inspiration and might overcome obstacles already solved by the others. This work is organised in three major parts: a first section will be serving as an introduction to each one of the enzymes regarding their structural and activity diversity, whereas a second one will be encompassing the mechanistic aspects of their catalysis. In this regard, the machineries that lead to analogous catalytic outcomes are depicted, highlighting the major differences and similarities. Finally, a third section will be focusing on the elements that allow the oxyfunctionalization chemistry to occur by delivering redox equivalents to the enzyme by the action of diverse redox partners. Redox partners are often overlooked in comparison to the catalytic counterparts, yet they represent fundamental elements to better understand and further develop practical applications based on mono- and peroxygenases.
Collapse
Affiliation(s)
- Davide Decembrino
- Photobiocatalysis Unit - Crop Production and Biostimulation Lab (CPBL), and Biomass Transformation Lab (BTL), École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium.
| | - David Cannella
- Photobiocatalysis Unit - Crop Production and Biostimulation Lab (CPBL), and Biomass Transformation Lab (BTL), École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium.
| |
Collapse
|
2
|
Cantera S, Rodríguez E, Santaella Vecchini N, López JC, García-Encina PA, Sousa DZ, Muñoz R. Resilience and robustness of alphaproteobacterial methanotrophs upon methane feast-famine scenarios. ENVIRONMENTAL RESEARCH 2023; 239:117376. [PMID: 37832766 DOI: 10.1016/j.envres.2023.117376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/27/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Most of methane (CH4) emissions contain low CH4 concentrations and typically occur at irregular intervals, which hinders the implementation and performance of methane abatement processes. This study aimed at understanding the metabolic mechanisms that allow methane oxidizing bacteria (MOB) to survive for long periods of time under methane starvation. To this aim, we used an omics-approach and studied the diversity and metabolism of MOB and non-MOB in bioreactors exposed to low CH4 concentrations under feast-famine cycles of 5 days and supplied with nutrient-rich broth. The 16S rRNA and the pmoA transcripts revealed that the most abundant and active MOB during feast and famine conditions belonged to the alphaproteobacterial genus Methylocystis (91-65%). The closest Methylocystis species were M. parvus and M. echinoides. Nitrifiers and denitrifiers were the most representative non-MOB communities, which likely acted as detoxifiers of the system. During starvation periods, the induced activity of CH4 oxidation was not lost, with the particulate methane monooxygenase of alphaproteobacterial MOB playing a key role in energy production. The polyhydroxyalkanoate and nitrification metabolisms of MOB had also an important role during feast-famine cycles, maintaining cell viability when CH4 concentrations were negligible. This research shows that there is an emergence and resilience of conventional alphaproteobacterial MOB, being the genus Methylocystis a centrepiece in environments exposed to dilute and intermittent methane emissions. This knowledge can be applied to the operation of bioreactors subjected to the treatment of dilute and discontinuous emissions via controlled bioaugmentation.
Collapse
Affiliation(s)
- Sara Cantera
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708WE, Wageningen, the Netherlands.
| | - Elisa Rodríguez
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Nicolás Santaella Vecchini
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708WE, Wageningen, the Netherlands
| | - Juan Carlos López
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Pedro A García-Encina
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708WE, Wageningen, the Netherlands
| | - Raul Muñoz
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain.
| |
Collapse
|
3
|
Fenibo EO, Selvarajan R, Wang H, Wang Y, Abia ALK. Untapped talents: insight into the ecological significance of methanotrophs and its prospects. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166145. [PMID: 37579801 DOI: 10.1016/j.scitotenv.2023.166145] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/06/2023] [Accepted: 08/06/2023] [Indexed: 08/16/2023]
Abstract
The deep ocean is a rich reservoir of unique organisms with great potential for bioprospecting, ecosystem services, and the discovery of novel materials. These organisms thrive in harsh environments characterized by high hydrostatic pressure, low temperature, and limited nutrients. Hydrothermal vents and cold seeps, prominent features of the deep ocean, provide a habitat for microorganisms involved in the production and filtration of methane, a potent greenhouse gas. Methanotrophs, comprising archaea and bacteria, play a crucial role in these processes. This review examines the intricate relationship between the roles, responses, and niche specialization of methanotrophs in the deep ocean ecosystem. Our findings reveal that different types of methanotrophs dominate specific zones depending on prevailing conditions. Type I methanotrophs thrive in oxygen-rich zones, while Type II methanotrophs display adaptability to diverse conditions. Verrumicrobiota and NC10 flourish in hypoxic and extreme environments. In addition to their essential role in methane regulation, methanotrophs contribute to various ecosystem functions. They participate in the degradation of foreign compounds and play a crucial role in cycling biogeochemical elements like metals, sulfur, and nitrogen. Methanotrophs also serve as a significant energy source for the oceanic food chain and drive chemosynthesis in the deep ocean. Moreover, their presence offers promising prospects for biotechnological applications, including the production of valuable compounds such as polyhydroxyalkanoates, methanobactin, exopolysaccharides, ecotines, methanol, putrescine, and biofuels. In conclusion, this review highlights the multifaceted roles of methanotrophs in the deep ocean ecosystem, underscoring their ecological significance and their potential for advancements in biotechnology. A comprehensive understanding of their niche specialization and responses will contribute to harnessing their full potential in various domains.
Collapse
Affiliation(s)
- Emmanuel Oliver Fenibo
- World Bank Africa Centre of Excellence, Centre for Oilfield Chemical Research, University of Port Harcourt, Port Harcourt 500272, Nigeria
| | - Ramganesh Selvarajan
- Laboratory of Extraterrestrial Ocean Systems (LEOS), Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS), Sanya, China; Department of Environmental Science, University of South Africa, Florida Campus, 1710, South Africa
| | - Huiqi Wang
- Laboratory of Extraterrestrial Ocean Systems (LEOS), Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS), Sanya, China
| | - Yue Wang
- Laboratory of Extraterrestrial Ocean Systems (LEOS), Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS), Sanya, China
| | - Akebe Luther King Abia
- Environmental Research Foundation, Westville 3630, South Africa; Antimicrobial Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
| |
Collapse
|
4
|
Sahoo KK, Katari JK, Das D. Recent advances in methanol production from methanotrophs. World J Microbiol Biotechnol 2023; 39:360. [PMID: 37891430 DOI: 10.1007/s11274-023-03813-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023]
Abstract
Methanol, the simplest aliphatic molecule of the alcohol family, finds diverse range of applications as an industrial solvent, a precursor for producing other chemicals (e.g., dimethyl ether, acetic acid and formaldehyde), and a potential fuel. There are conventional chemical routes for methanol production such as, steam reforming of natural gas to form syngas, followed by catalytic conversion into methanol; direct catalytic oxidation of methane, or hydrogenation of carbon dioxide. However, these chemical routes are limited by the requirement for expensive catalysts and extreme process conditions, and plausible environmental implications. Alternatively, methanotrophic microorganisms are being explored as biological alternative for methanol production, under milder process conditions, bypassing the requirement for chemical catalysts, and without imposing any adverse environmental impact. Methanotrophs possess inherent metabolic pathways for methanol production via biological methane oxidation or carbon dioxide reduction, thus offering a surplus advantage pertaining to the sequestration of two major greenhouse gases. This review sheds light on the recent advances in methanotrophic methanol production including metabolic pathways, feedstocks, metabolic engineering, and bioprocess engineering approaches. Furthermore, various reactor configurations are discussed in view of the challenges associated with solubility and mass transfer limitations in methanotrophic gas fermentation systems.
Collapse
Affiliation(s)
- Krishna Kalyani Sahoo
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, 781039, Assam, India
| | - John Kiran Katari
- School of Energy Science & Engineering, Indian Institute of Technology, Guwahati, 781039, Assam, India
| | - Debasish Das
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, 781039, Assam, India.
- School of Energy Science & Engineering, Indian Institute of Technology, Guwahati, 781039, Assam, India.
| |
Collapse
|
5
|
Mrudulakumari Vasudevan U, Mai DHA, Krishna S, Lee EY. Methanotrophs as a reservoir for bioactive secondary metabolites: Pitfalls, insights and promises. Biotechnol Adv 2023; 63:108097. [PMID: 36634856 DOI: 10.1016/j.biotechadv.2023.108097] [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: 10/03/2022] [Revised: 12/10/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023]
Abstract
Methanotrophs are potent natural producers of several bioactive secondary metabolites (SMs) including isoprenoids, polymers, peptides, and vitamins. Cryptic biosynthetic gene clusters identified from these microbes via genome mining hinted at the vast and hidden SM biosynthetic potential of these microbes. Central carbon metabolism in methanotrophs offers rare pathway intermediate pools that could be further diversified using advanced synthetic biology tools to produce valuable SMs; for example, plant polyketides, rare carotenoids, and fatty acid-derived SMs. Recent advances in pathway reconstruction and production of isoprenoids, squalene, ectoine, polyhydroxyalkanoate copolymer, cadaverine, indigo, and shinorine serve as proof-of-concept. This review provides theoretical guidance for developing methanotrophs as microbial chassis for high-value SMs. We summarize the distinct secondary metabolic potentials of type I and type II methanotrophs, with specific attention to products relevant to biomedical applications. This review also includes native and non-native SMs from methanotrophs, their therapeutic potential, strategies to induce silent biosynthetic gene clusters, and challenges.
Collapse
Affiliation(s)
- Ushasree Mrudulakumari Vasudevan
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Dung Hoang Anh Mai
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Shyam Krishna
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea.
| |
Collapse
|
6
|
Wang S, Sun P, Liu J, Xu Y, Dolfing J, Wu Y. Distribution of methanogenic and methanotrophic consortia at soil-water interfaces in rice paddies across climate zones. iScience 2022; 26:105851. [PMID: 36636345 PMCID: PMC9829807 DOI: 10.1016/j.isci.2022.105851] [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] [Received: 08/29/2022] [Revised: 11/15/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Periphytic biofilms (PB) at the soil-water interface contributes 7-38% of the methane emission from rice paddies, yet the biogeographical mechanism underlying and affecting the process remain elusive. In this study, rice fields along an edapho-vclimatic gradient were sampled, and the environmental drivers affecting distribution of methanogenic and methanotrophic communities were evaluated. The methanogenic and methanotrophic communities at soil-water interface showed less complex inter/intra-generic interactions than those in soil, and their relative abundances were weakly driven by spatial distance, soil organic carbon, soil total nitrogen and pH. The nutrient supply and buffering capacity of extracellular polymeric substance released by PB reduced their interaction and enhanced the resilience on edaphic environment changes. Climate affected soil metal content, extracellular polymeric substance content, and thus the methane-related communities, and caused geographical variation in the impacts of PB on methane emissions from rice paddies. This study facilitates our understanding of geographical differences in the contribution of PB to methane emission.
Collapse
Affiliation(s)
- Sichu Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China,Institute of Agricultural Resources and Environment, Jiangsu Academy of Agriculture Sciences (JAAS), 50 Zhongling Road, Nanjing 210014, China,Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People’s Republic of China, Shuitianba Zigui, Yichang 443605, China
| | - Pengfei Sun
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China,Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People’s Republic of China, Shuitianba Zigui, Yichang 443605, China
| | - Junzhuo Liu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China,Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People’s Republic of China, Shuitianba Zigui, Yichang 443605, China
| | - Ying Xu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China,Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People’s Republic of China, Shuitianba Zigui, Yichang 443605, China
| | - Jan Dolfing
- Faculty of Energy and Environment, Northumbria University, Newcastle upon Tyne NE1 8QH, UK
| | - Yonghong Wu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China,Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People’s Republic of China, Shuitianba Zigui, Yichang 443605, China,Corresponding author
| |
Collapse
|
7
|
Kulkarni PP, Chavan SB, Deshpande MS, Sagotra D, Kumbhar PS, Ghosalkar AR. Enrichment of Methylocystis dominant mixed culture from rice field for PHB production. J Biotechnol 2022; 343:62-70. [PMID: 34838616 DOI: 10.1016/j.jbiotec.2021.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 11/16/2022]
Abstract
Presence of methanotrophs in diverse environmental habitats helps to reduce emissions of greenhouse gas like methane. Isolation and culture of undiscovered wealth of methanotrophic organisms can help in exploitation of these organisms in value added products. The present study focuses on the enrichment of methanotroph dominated mixed microbial community by use of three stage strategy of revival, proliferation, and segregation. During the enrichment process amplicon sequencing of 16 s rRNA V3-V4 region showed relative abundance of mixed culture comprising single methanotrophic species of Methylocystis genus (88.92%) along with only three other species. Methylocystis dominant mixed culture (MMI-11) was observed to produce polyhydroxyalkanoates (PHA). During studies to identify favourable culture conditions, nitrate was found to be preferred nitrogen source for growth and PHA production. Cell growth ability to produce PHA was also evaluated at 14 L fermentor by supplying gas using continuous bubbling and through pressurization in the headspace. The mixed methanotrophic culture was found to accumulate maximum of 22.20% polyhydroxybutyrate (PHB) under nitrate limited condition. The molecular weight of PHB was found to be 2.221 × 105 g mol-1 with polydispersity of 1.82.
Collapse
Affiliation(s)
- Pranav P Kulkarni
- Department of Technology, Savitribai Phule Pune University, Pune, India; Praj Matrix - R&D Centre, division of Praj Industries Limited, Urawade, Pune, India
| | - Sambhaji B Chavan
- Praj Matrix - R&D Centre, division of Praj Industries Limited, Urawade, Pune, India
| | - Mandar S Deshpande
- Praj Matrix - R&D Centre, division of Praj Industries Limited, Urawade, Pune, India
| | - Dhanishta Sagotra
- Department of Technology, Savitribai Phule Pune University, Pune, India
| | - Pramod S Kumbhar
- Praj Matrix - R&D Centre, division of Praj Industries Limited, Urawade, Pune, India
| | - Anand R Ghosalkar
- Department of Technology, Savitribai Phule Pune University, Pune, India; Praj Matrix - R&D Centre, division of Praj Industries Limited, Urawade, Pune, India.
| |
Collapse
|
8
|
Gęsicka A, Oleskowicz-Popiel P, Łężyk M. Recent trends in methane to bioproduct conversion by methanotrophs. Biotechnol Adv 2021; 53:107861. [PMID: 34710553 DOI: 10.1016/j.biotechadv.2021.107861] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 10/11/2021] [Accepted: 10/20/2021] [Indexed: 12/26/2022]
Abstract
Methane is an abundant and low-cost gas with high global warming potential and its use as a feedstock can help mitigate climate change. Variety of valuable products can be produced from methane by methanotrophs in gas fermentation processes. By using methane as a sole carbon source, methanotrophic bacteria can produce bioplastics, biofuels, feed additives, ectoine and variety of other high-value chemical compounds. A lot of studies have been conducted through the years for natural methanotrophs and engineered strains as well as methanotrophic consortia. These have focused on increasing yields of native products as well as proof of concept for the synthesis of new range of chemicals by metabolic engineering. This review shows trends in the research on key methanotrophic bioproducts since 2015. Despite certain limitations of the known production strategies that makes commercialization of methane-based products challenging, there is currently much attention placed on the promising further development.
Collapse
Affiliation(s)
- Aleksandra Gęsicka
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Piotr Oleskowicz-Popiel
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland.
| | - Mateusz Łężyk
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland.
| |
Collapse
|
9
|
Sahoo KK, Goswami G, Das D. Biotransformation of Methane and Carbon Dioxide Into High-Value Products by Methanotrophs: Current State of Art and Future Prospects. Front Microbiol 2021; 12:636486. [PMID: 33776968 PMCID: PMC7987672 DOI: 10.3389/fmicb.2021.636486] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/22/2021] [Indexed: 01/16/2023] Open
Abstract
Conventional chemical methods to transform methane and carbon dioxide into useful chemicals are plagued by the requirement for extreme operating conditions and expensive catalysts. Exploitation of microorganisms as biocatalysts is an attractive alternative to sequester these C1 compounds and convert them into value-added chemicals through their inherent metabolic pathways. Microbial biocatalysts are advantageous over chemical processes as they require mild-operating conditions and do not release any toxic by-products. Methanotrophs are potential cell-factories for synthesizing a wide range of high-value products via utilizing methane as the sole source of carbon and energy, and hence, serve as excellent candidate for methane sequestration. Besides, methanotrophs are capable of capturing carbon dioxide and enzymatically hydrogenating it into methanol, and hence qualify to be suitable candidates for carbon dioxide sequestration. However, large-scale production of value-added products from methanotrophs still presents an overwhelming challenge, due to gas-liquid mass transfer limitations, low solubility of gases in liquid medium and low titer of products. This requires design and engineering of efficient reactors for scale-up of the process. The present review offers an overview of the metabolic architecture of methanotrophs and the range of product portfolio they can offer. Special emphasis is given on methanol biosynthesis as a potential biofuel molecule, through utilization of methane and alternate pathway of carbon dioxide sequestration. In view of the gas-liquid mass transfer and low solubility of gases, the key rate-limiting step in gas fermentation, emphasis is given toward reactor design consideration essential to achieve better process performance.
Collapse
Affiliation(s)
- Krishna Kalyani Sahoo
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - Gargi Goswami
- Department of Biotechnology, Gandhi Institute of Technology and Management (GITAM) University, Visakhapatnam, India
| | - Debasish Das
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| |
Collapse
|
10
|
|
11
|
Hakobyan A, Zhu J, Glatter T, Paczia N, Liesack W. Hydrogen utilization by Methylocystis sp. strain SC2 expands the known metabolic versatility of type IIa methanotrophs. Metab Eng 2020; 61:181-196. [PMID: 32479801 DOI: 10.1016/j.ymben.2020.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 03/20/2020] [Accepted: 05/01/2020] [Indexed: 12/19/2022]
Abstract
Methane, a non-expensive natural substrate, is used by Methylocystis spp. as a sole source of carbon and energy. Here, we assessed whether Methylocystis sp. strain SC2 is able to also utilize hydrogen as an energy source. The addition of 2% H2 to the culture headspace had the most significant positive effect on the growth yield under CH4 (6%) and O2 (3%) limited conditions. The SC2 biomass yield doubled from 6.41 (±0.52) to 13.82 (±0.69) mg cell dry weight per mmol CH4, while CH4 consumption was significantly reduced. Regardless of H2 addition, CH4 utilization was increasingly redirected from respiration to fermentation-based pathways with decreasing O2/CH4 mixing ratios. Theoretical thermodynamic calculations confirmed that hydrogen utilization under oxygen-limited conditions doubles the maximum biomass yield compared to fully aerobic conditions without H2 addition. Hydrogen utilization was linked to significant changes in the SC2 proteome. In addition to hydrogenase accessory proteins, the production of Group 1d and Group 2b hydrogenases was significantly increased in both short- and long-term incubations. Both long-term incubation with H2 (37 d) and treatments with chemical inhibitors revealed that SC2 growth under hydrogen-utilizing conditions does not require the activity of complex I. Apparently, strain SC2 has the metabolic capacity to channel hydrogen-derived electrons into the quinone pool, which provides a link between hydrogen oxidation and energy production. In summary, H2 may be a promising alternative energy source in biotechnologically oriented methanotroph projects that aim to maximize biomass yield from CH4, such as the production of high-quality feed protein.
Collapse
Affiliation(s)
- Anna Hakobyan
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Jing Zhu
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; Institute of Environmental Science and Technology, Zhejiang University, Hangzhou, China
| | - Timo Glatter
- Core Facility for Mass Spectrometry and Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Nicole Paczia
- Core Facility for Metabolomics and Small Molecule Mass Spectrometry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Werner Liesack
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany.
| |
Collapse
|
12
|
|
13
|
Akberdin IR, Collins DA, Hamilton R, Oshchepkov DY, Shukla AK, Nicora CD, Nakayasu ES, Adkins JN, Kalyuzhnaya MG. Rare Earth Elements Alter Redox Balance in Methylomicrobium alcaliphilum 20Z R. Front Microbiol 2018; 9:2735. [PMID: 30542328 PMCID: PMC6277846 DOI: 10.3389/fmicb.2018.02735] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/25/2018] [Indexed: 12/25/2022] Open
Abstract
Background: Rare Earth Elements (REEs) control methanol utilization in both methane- and methanol-utilizing microbes. It has been established that the addition of REEs leads to the transcriptional repression of MxaFI-MeDH [a two-subunit methanol dehydrogenase (MeDH), calcium-dependent] and the activation of XoxF-MeDH (a one-subunit MeDH, lanthanum-dependent). Both enzymes are pyrroquinoline quinone-dependent alcohol dehydrogenases and show significant homology; however, they display different kinetic properties and substrate specificities. This study investigates the impact of the MxaFI to XoxF switch on the behavior of metabolic networks at a global scale. Results: In this study we investigated the steady-state growth of Methylomicrobium alcaliphilum 20ZR in media containing calcium (Ca) or lanthanum (La, a REE element). We found that cells supplemented with La show a higher growth rate compared to Ca-cultures; however, the efficiency of carbon conversion, estimated as biomass yield, is higher in cells grown with Ca. Three complementary global-omics approaches–RNA-seq transcriptomics, proteomics, and metabolomics–were applied to investigate the mechanisms of improved growth vs. carbon conversion. Cells grown with La showed the transcriptional activation of the xoxF gene, a homolog of the formaldehyde-activating enzyme (fae2), a putative transporter, genes for hemin-transport proteins, and nitrate reductase. In contrast, genes for mxaFI and associated cytochrome (mxaG) expression were downregulated. Proteomic profiling suggested additional adjustments of the metabolic network at the protein level, including carbon assimilation pathways, electron transport systems, and the tricarboxylic acid (TCA) cycle. Discord between gene expression and protein abundance changes points toward the possibility of post-transcriptional control of the related systems including key enzymes of the TCA cycle and a set of electron-transport carriers. Metabolomic data followed proteomics and showed the reduction of the ribulose-monophosphate (RuMP) pathway intermediates and the increase of the TCA cycle metabolites. Conclusion: Cells exposed to REEs display higher rates of growth but have lower carbon conversion efficiency compared to cells supplemented with Ca. The most plausible explanation for these physiological changes is an increased conversion of methanol into formate by XoxF-MeDH, which further stimulates methane oxidation but limits both the supply of reducing power and flux of formaldehyde into the RuMP pathway.
Collapse
Affiliation(s)
- Ilya R Akberdin
- Biology Department, Viral Information Institute, San Diego State University, San Diego, CA, United States.,Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia.,Novosibirsk State University, Novosibirsk, Russia
| | - David A Collins
- Biology Department, Viral Information Institute, San Diego State University, San Diego, CA, United States
| | - Richard Hamilton
- Biology Department, Viral Information Institute, San Diego State University, San Diego, CA, United States
| | | | - Anil K Shukla
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Carrie D Nicora
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Ernesto S Nakayasu
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Joshua N Adkins
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Marina G Kalyuzhnaya
- Biology Department, Viral Information Institute, San Diego State University, San Diego, CA, United States
| |
Collapse
|
14
|
Hakobyan A, Liesack W, Glatter T. Crude-MS Strategy for in-Depth Proteome Analysis of the Methane-Oxidizing Methylocystis sp. strain SC2. J Proteome Res 2018; 17:3086-3103. [DOI: 10.1021/acs.jproteome.8b00216] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Werner Liesack
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Karl-von-Frisch-Str. 16, D-35043 Marburg, Germany
| | | |
Collapse
|
15
|
Xing Z, Zhao T, Zhang L, Gao Y, Liu S, Yang X. Effects of copper on expression of methane monooxygenases, trichloroethylene degradation, and community structure in methanotrophic consortia. Eng Life Sci 2018; 18:236-243. [PMID: 32624902 DOI: 10.1002/elsc.201700153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/12/2017] [Accepted: 12/29/2017] [Indexed: 11/08/2022] Open
Abstract
Copper plays a key role in regulating the expression of enzymes that promote biodegradation of contaminants in methanotrophic consortia (MC). Here, we utilized MC isolated from landfill cover to investigate cometabolic degradation of trichloroethylene (TCE) at nine different copper (Cu2+) concentrations. The results demonstrated that an increase in Cu2+ concentration from 0 to 15 μM altered the specific first-order rate constant k 1,TCE, the expression levels of methane monooxygenase (pmoA and mmoX) genes, and the specific activity of soluble methane monooxygenase (sMMO). High efficiency TCE degradation (95%) and the expression levels of methane monooxygenase (MMO) were detected at a Cu2+ concentration of 0.03 μM. Notably, sMMO-specific activity ranged from 74.41 nmol/(mgcell h) in 15 μM Cu2+ to 654.99 nmol/(mgcell h) in 0.03 μM Cu2+, which contrasts with cultures of pure methanotrophs in which sMMO activity is depressed at high Cu2+ concentrations, indicating a special regulatory role for Cu2+ in MC. The results of MiSeq pyrosequencing indicated that higher Cu2+ concentrations stimulated the growth of methanotrophic microorganisms in MC. These findings have important implications for the elucidation of copper-mediated regulatory mechanisms in MC.
Collapse
Affiliation(s)
- Zhilin Xing
- Faculty of Urban Construction and Environment Engineering Chongqing University Chongqing P. R. China.,School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| | - Tiantao Zhao
- Faculty of Urban Construction and Environment Engineering Chongqing University Chongqing P. R. China.,School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| | - Lijie Zhang
- School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| | - Yanhui Gao
- Faculty of Urban Construction and Environment Engineering Chongqing University Chongqing P. R. China.,School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| | - Shuai Liu
- School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| | - Xu Yang
- School of Chemistry and Chemical Engineering Chongqing University of Technology Chongqing P. R. China
| |
Collapse
|
16
|
Stone KA, Hilliard MV, He QP, Wang J. A mini review on bioreactor configurations and gas transfer enhancements for biochemical methane conversion. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2017.09.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
17
|
Chidambarampadmavathy K, Karthikeyan OP, Huerlimann R, Maes GE, Heimann K. Responses of mixed methanotrophic consortia to variable Cu 2+/Fe 2+ ratios. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2017; 197:159-166. [PMID: 28365562 DOI: 10.1016/j.jenvman.2017.03.063] [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: 10/22/2016] [Revised: 03/14/2017] [Accepted: 03/21/2017] [Indexed: 05/22/2023]
Abstract
Methane mitigation in landfill top cover soils is mediated by methanotrophs whose optimal methane (CH4) oxidation capacity is governed by environmental and complex microbial community interactions. Optimization of CH4 remediating bio-filters need to take microbial responses into account. Divalent copper (Cu2+) and iron (Fe2+) are present in landfills at variable ratios and play a vital role in methane oxidation capacity and growth of methanotrophs. This study, as a first of its kind, therefore quantified effects of variable Cu2+ and Fe2+ (5:5, 5:25 and 5:50 μM) ratios on mixed methanotrophic communities enriched from landfill top cover (LB) and compost soils (CB). CH4 oxidation capacity, CH4 removal efficiencies, fatty acids content/profiles and polyhydroxybutyrate (PHB; a biopolymer) contents were also analysed to quantify performance and potential co-product development. Mixed methanotroph cultures were raised in 10 L continuous stirred tank reactors (CSTRs, Bioflo® & Celligen® 310 Fermentor/Bioreactor; John Morris Scientific, Chatswood, NSW, Australia). Community structure was determined by amplifying the V3-V4 region of 16s rRNA gene. Community structure and, consequently, fatty acid-profiles changed significantly with increasing Cu2+/Fe2+ ratios, and responses were different for LB and CB. Effects on methane oxidation capacities and PHB content were similar in the LB- and CB-CSTR, decreasing with increasing Cu2+/Fe2+ ratios, while biomass growth was unaffected. In general, high Fe2+ concentration favored growth of the type -II methanotroph Methylosinus in the CB-CSTR, but methanotroph abundances decreased in the LB-CSTR. Increase in Cu2+/Fe2+ ratio increased the growth of Sphingopyxis in both systems, while Azospirllum was co-dominant in the LB- but absent in the CB-CSTR. After 13 days, methane oxidation capacities and PHB content decreased by ∼50% and more in response to increasing Fe2+ concentrations. Although methanotroph abundance was ∼2% in the LB- (compared to >50% in CB-CSTR), methane oxidation capacities were comparable in the two systems, suggesting that methane oxidation capacity was maintained by the dominant Azospirllum and Sphingopyxis in the LB-CSTR. Despite similar methanotroph inoculum community composition and controlled environmental variables, increasing Cu2+/Fe2+ ratios resulted in significantly different microbial community structures in the LB- and CB-CSTR, indicative of complex microbial interactions. In summary, our results suggest that a detailed understanding of allelopathic interactions in mixed methanotrophic consortia is vital for constructing robust bio-filters for CH4 emission abatement.
Collapse
Affiliation(s)
- Karthigeyan Chidambarampadmavathy
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - Obulisamy Parthiba Karthikeyan
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Sino-Forest Applied Research Centre for Pearl River Delta Environment (ARCPE), Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Roger Huerlimann
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - Gregory E Maes
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - Kirsten Heimann
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Centre for Bio-discovery and Molecular Development of Therapeutics, James Cook University, Townsville 4811, Queensland, Australia.
| |
Collapse
|
18
|
Chidambarampadmavathy K, Karthikeyan OP, Huerlimann R, Maes GE, Heimann K. Response of mixed methanotrophic consortia to different methane to oxygen ratios. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 61:220-228. [PMID: 27876290 DOI: 10.1016/j.wasman.2016.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 08/31/2016] [Accepted: 11/04/2016] [Indexed: 05/22/2023]
Abstract
Methane (CH4) and oxygen (air) concentrations affect the CH4 oxidation capacity (MOC) and mixed methanotrophic community structures in compost (fresh) and landfill (age old) top cover soils. A change in the mixed methanotrophic community structure in response has implications for landfill CH4 bio-filter remediation and possible bio-product outcomes (i.e., fatty acid methyl esters (FAME) content and profiles and polyhydroxybutyrate (PHB) contents). Therefore the study aimed to evaluate the effect of variable CH4 to oxygen ratios (10-50% CH4 in air) on mixed methanotrophic community structures enriched from landfill top cover (LB) and compost soils (CB) and to quantify flow on impacts on MOC, total FAME contents and profiles, and PHB accumulation. A stable consortium developed achieving average MOCs of 3.0±0.12, 4.1±0.26, 6.9±0.7, 7.6±1.3 and 9.2±1.2mgCH4g-1DWbiomassh-1 in LB and 2.9±0.04, 5.05±0.32, 6.7±0.31, 7.9±0.61 and 8.6±0.48mgCH4g-1DWbiomassh-1 in CB for a 20day cultivation period at 10, 20, 30, 40 and 50% CH4, respectively. CB at 10% CH4 had a maximal FAME content of 40.5±0.8mgFAMEg-1DWbiomass, while maximal PHB contents (25mgg-1DWbiomass) was observed at 40% CH4 in LB. Despite variable CH4/O2 ratios, the mixed methanotrophic community structures in both LB and CB were relatively stable, dominated by Methylosarcina sp., and Chryseobacterium, suggesting that a resilient consortium had formed which can now be tested in bio-filter operations for CH4 mitigations in landfills.
Collapse
Affiliation(s)
- K Chidambarampadmavathy
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - O P Karthikeyan
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Sino-Forest Applied Research Centre for Pearl River Delta Environment (ARCPE), Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region
| | - R Huerlimann
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - G E Maes
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Center for Human Genetics, Genomics Core, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - K Heimann
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Centre for Bio-discovery and Molecular Development of Therapeutics, James Cook University, Townsville 4811, Queensland, Australia.
| |
Collapse
|
19
|
Strong PJ, Laycock B, Mahamud SNS, Jensen PD, Lant PA, Tyson G, Pratt S. The Opportunity for High-Performance Biomaterials from Methane. Microorganisms 2016; 4:E11. [PMID: 27681905 PMCID: PMC5029516 DOI: 10.3390/microorganisms4010011] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/15/2016] [Accepted: 01/22/2016] [Indexed: 01/18/2023] Open
Abstract
Polyhydroxyalkanoate (PHA) biopolymers are widely recognised as outstanding candidates to replace conventional petroleum-derived polymers. Their mechanical properties are good and can be tailored through copolymer composition, they are biodegradable, and unlike many alternatives, they do not rely on oil-based feedstocks. Further, they are the only commodity polymer that can be synthesised intracellularly, ensuring stereoregularity and high molecular weight. However, despite offering enormous potential for many years, they are still not making a significant impact. This is broadly because commercial uptake has been limited by variable performance (inconsistent polymer properties) and high production costs of the raw polymer. Additionally, the main type of PHA produced naturally is poly-3-hydroxybutyrate (PHB), which has limited scope due to its brittle nature and low thermal stability, as well as its tendency to embrittle over time. Production cost is strongly impacted by the type of the feedstock used. In this article we consider: the production of PHAs from methanotrophs using methane as a cost-effective substrate; the use of mixed cultures, as opposed to pure strains; and strategies to generate a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer (PHBV), which has more desirable qualities such as toughness and elasticity.
Collapse
Affiliation(s)
- Peter James Strong
- Centre for Solid Waste Bioprocessing, School of Civil Engineering and School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Bronwyn Laycock
- School of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
| | | | - Paul Douglas Jensen
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Paul Andrew Lant
- School of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
| | - Gene Tyson
- Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Steven Pratt
- School of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
| |
Collapse
|
20
|
Karthikeyan OP, Chidambarampadmavathy K, Nadarajan S, Lee PKH, Heimann K. Effect of CH4/O2 ratio on fatty acid profile and polyhydroxybutyrate content in a heterotrophic-methanotrophic consortium. CHEMOSPHERE 2015; 141:235-42. [PMID: 26247542 DOI: 10.1016/j.chemosphere.2015.07.054] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/14/2015] [Accepted: 07/19/2015] [Indexed: 05/22/2023]
Abstract
Understanding the role of heterotrophic-methanotrophic (H-Meth) communities is important for improvement of methane (CH4) oxidation capacities (MOC) particularly in conjunction with bio-product development in industrial bio-filters. Initially, a H-Meth consortium was established and enriched from marine sediments and characterized by next generation sequencing of the 16s rDNA gene. The enriched consortium was subjected to 10-50% CH4 (i.e., 0.20-1.6 CH4/O2 ratios) to study the effects on MOCs, biomass growth, fatty acid profiles and biopolymer (e.g. polyhydroxybutyrate; PHB) content. Methylocystis, Methylophaga and Pseudoxanthomonas dominated the H-Meth consortium. Culture enrichment of the H-Meth consortium resulted in 15-20-folds higher MOC compared to seed sediments. Increasing CH4 concentration (and decreased O2 levels) yielded higher MOCs, but did not improve total fatty acid contents. PHB contents varied between 2.5% and 8.5% independently of CH4/O2 ratios. The results suggest that H-Meth consortia could potentially be used in industrial bio-filters for production of biopolymer/biofuel precursors from CH4.
Collapse
Affiliation(s)
- Obulisamy P Karthikeyan
- College of Marine and Environmental Sciences, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia
| | - Karthigeyan Chidambarampadmavathy
- College of Marine and Environmental Sciences, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - Saravanan Nadarajan
- College of Marine and Environmental Sciences, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia
| | - Patrick K H Lee
- School of Energy and Environment, City University of Hong Kong, Hong Kong
| | - Kirsten Heimann
- College of Marine and Environmental Sciences, James Cook University, Townsville 4811, Queensland, Australia; Centre for Sustainable Fisheries and Aquaculture, James Cook University, Townsville 4811, Queensland, Australia; Comparative Genomics Centre, James Cook University, Townsville 4811, Queensland, Australia; Centre for Bio-discovery and Molecular Development of Therapeutics, James Cook University, Townsville 4811, Queensland, Australia.
| |
Collapse
|