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Bhat EH, Henard JM, Lee SA, McHalffey D, Ravulapati MS, Rogers EV, Yu L, Skiles D, Henard CA. Construction of a broad-host-range Anderson promoter series and particulate methane monooxygenase promoter variants expand the methanotroph genetic toolbox. Synth Syst Biotechnol 2024; 9:250-258. [PMID: 38435708 PMCID: PMC10909576 DOI: 10.1016/j.synbio.2024.02.003] [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: 01/06/2024] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 03/05/2024] Open
Abstract
Methanotrophic bacteria are currently used industrially for the bioconversion of methane-rich natural gas and anaerobic digestion-derived biogas to valuable products. These bacteria may also serve to mitigate the negative effects of climate change by capturing atmospheric greenhouse gases. Several genetic tools have previously been developed for genetic and metabolic engineering of methanotrophs. However, the available tools for use in methanotrophs are significantly underdeveloped compared to many other industrially relevant bacteria, which hinders genetic and metabolic engineering of these biocatalysts. As such, expansion of the methanotroph genetic toolbox is needed to further our understanding of methanotrophy and develop biotechnologies that leverage these unique microbes for mitigation and conversion of methane to valuable products. Here, we determined the copy number of three broad-host-range plasmids in Methylococcus capsulatus Bath and Methylosinus trichosporium OB3b, representing phylogenetically diverse Gammaproteobacterial and Alphaproteobacterial methanotrophs, respectively. Further, we show that the commonly used synthetic Anderson series promoters are functional and exhibit similar relative activity in M. capsulatus and M. trichosporium OB3b, but the synthetic series had limited range. Thus, we mutagenized the native M. capsulatus particulate methane monooxygenase promoter and identified variants with activity that expand the activity range of synthetic, constitutive promoters functional not only in M. capsulatus, but also in Escherichia coli. Collectively, the tools developed here advance the methanotroph genetic engineering toolbox and represent additional synthetic genetic parts that may have broad applicability in Pseudomonadota bacteria.
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Affiliation(s)
| | | | | | - Dustin McHalffey
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Mahith S. Ravulapati
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Elle V. Rogers
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Logan Yu
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - David Skiles
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Calvin A. Henard
- Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, USA
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Corrêa PS, Fernandes MA, Jimenez CR, Mendes LW, Lima PDMT, Abdalla AL, Louvandini H. Interaction between methanotrophy and gastrointestinal nematodes infection on the rumen microbiome of lambs. FEMS Microbiol Ecol 2024; 100:fiae083. [PMID: 38821514 PMCID: PMC11165275 DOI: 10.1093/femsec/fiae083] [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: 07/28/2023] [Revised: 03/21/2024] [Accepted: 05/29/2024] [Indexed: 06/02/2024] Open
Abstract
Complex cross-talk occurs between gastrointestinal nematodes and gut symbiotic microbiota, with consequences for animal metabolism. To investigate the connection between methane production and endoparasites, this study evaluated the effect of mixed infection with Haemonchus contortus and Trichostrongylus colubriformis on methanogenic and methanotrophic community in rumen microbiota of lambs using shotgun metagenomic and real-time quantitative PCR (qPCR). The rumen content was collected from six Santa Inês lambs, (7 months old) before and after 42 days infection by esophageal tube. The metagenomic analysis showed that the infection affected the microbial community structure leading to decreased abundance of methanotrophs bacteria, i.e. α-proteobacteria and β-proteobacteria, anaerobic methanotrophic archaea (ANME), protozoa, sulfate-reducing bacteria, syntrophic bacteria with methanogens, geobacter, and genes related to pyruvate, fatty acid, nitrogen, and sulfur metabolisms, ribulose monophosphate cycle, and Entner-Doudoroff Pathway. Additionally, the abundance of methanogenic archaea and the mcrA gene did not change. The co-occurrence networks enabled us to identify the interactions between each taxon in microbial communities and to determine the reshaping of rumen microbiome associations by gastrointestinal nematode infection. Besides, the correlation between ANMEs was lower in the animal's postinfection. Our findings suggest that gastrointestinal parasites potentially lead to decreased methanotrophic metabolism-related microorganisms and genes.
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Affiliation(s)
- Patricia Spoto Corrêa
- Laboratory of Animal Nutrition, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
| | - Murilo Antonio Fernandes
- Laboratory of Animal Nutrition, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
| | - Carolina Rodriguez Jimenez
- Laboratory of Animal Nutrition, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
| | - Lucas William Mendes
- Laboratory of Molecular Cell Biology, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
| | - Paulo de Mello Tavares Lima
- Department of Animal Science, University of Wyoming, 1000 East University Avenue, Laramie, WY 82071, United States
| | - Adibe Luiz Abdalla
- Laboratory of Animal Nutrition, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
| | - Helder Louvandini
- Laboratory of Animal Nutrition, Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenario Avenue, Piracicaba, SP 13416-000, Brazil
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Wutkowska M, Tláskal V, Bordel S, Stein LY, Nweze JA, Daebeler A. Leveraging genome-scale metabolic models to understand aerobic methanotrophs. THE ISME JOURNAL 2024; 18:wrae102. [PMID: 38861460 PMCID: PMC11195481 DOI: 10.1093/ismejo/wrae102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 05/20/2024] [Accepted: 06/10/2024] [Indexed: 06/13/2024]
Abstract
Genome-scale metabolic models (GEMs) are valuable tools serving systems biology and metabolic engineering. However, GEMs are still an underestimated tool in informing microbial ecology. Since their first application for aerobic gammaproteobacterial methane oxidizers less than a decade ago, GEMs have substantially increased our understanding of the metabolism of methanotrophs, a microbial guild of high relevance for the natural and biotechnological mitigation of methane efflux to the atmosphere. Particularly, GEMs helped to elucidate critical metabolic and regulatory pathways of several methanotrophic strains, predicted microbial responses to environmental perturbations, and were used to model metabolic interactions in cocultures. Here, we conducted a systematic review of GEMs exploring aerobic methanotrophy, summarizing recent advances, pointing out weaknesses, and drawing out probable future uses of GEMs to improve our understanding of the ecology of methane oxidizers. We also focus on their potential to unravel causes and consequences when studying interactions of methane-oxidizing bacteria with other methanotrophs or members of microbial communities in general. This review aims to bridge the gap between applied sciences and microbial ecology research on methane oxidizers as model organisms and to provide an outlook for future studies.
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Affiliation(s)
- Magdalena Wutkowska
- Institute of Soil Biology and Biogeochemistry, Biology Centre CAS, 370 05 České Budějovice, Czech Republic
| | - Vojtěch Tláskal
- Institute of Soil Biology and Biogeochemistry, Biology Centre CAS, 370 05 České Budějovice, Czech Republic
| | - Sergio Bordel
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Valladolid 47011, Spain
- Institute of Sustainable Processes, Valladolid 47011, Spain
| | - Lisa Y Stein
- Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Justus Amuche Nweze
- Institute of Soil Biology and Biogeochemistry, Biology Centre CAS, 370 05 České Budějovice, Czech Republic
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
- Department of Science Laboratory Technology, Faculty of Physical Sciences, University of Nigeria, Nsukka 410001, Nigeria
| | - Anne Daebeler
- Institute of Soil Biology and Biogeochemistry, Biology Centre CAS, 370 05 České Budějovice, Czech Republic
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Xie X, Deng X, Chen J, Chen L, Yuan J, Chen H, Wei C, Liu X, Qiu G. Two new clades recovered at high temperatures provide novel phylogenetic and genomic insights into Candidatus Accumulibacter. ISME COMMUNICATIONS 2024; 4:ycae049. [PMID: 38808122 PMCID: PMC11131965 DOI: 10.1093/ismeco/ycae049] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 05/30/2024]
Abstract
Candidatus Accumulibacter, a key genus of polyphosphate-accumulating organisms, plays key roles in lab- and full-scale enhanced biological phosphorus removal (EBPR) systems. A total of 10 high-quality Ca. Accumulibacter genomes were recovered from EBPR systems operated at high temperatures, providing significantly updated phylogenetic and genomic insights into the Ca. Accumulibacter lineage. Among these genomes, clade IIF members SCELSE-3, SCELSE-4, and SCELSE-6 represent the to-date known genomes encoding a complete denitrification pathway, suggesting that Ca. Accumulibacter alone could achieve complete denitrification. Clade IIC members SSA1, SCUT-1, SCELCE-2, and SCELSE-8 lack the entire set of denitrifying genes, representing to-date known non-denitrifying Ca. Accumulibacter. A pan-genomic analysis with other Ca. Accumulibacter members suggested that all Ca. Accumulibacter likely has the potential to use dicarboxylic amino acids. Ca. Accumulibacter aalborgensis AALB and Ca. Accumulibacter affinis BAT3C720 seemed to be the only two members capable of using glucose for EBPR. A heat shock protein Hsp20 encoding gene was found exclusively in genomes recovered at high temperatures, which was absent in clades IA, IC, IG, IIA, IIB, IID, IIG, and II-I members. High transcription of this gene in clade IIC members SCUT-2 and SCUT-3 suggested its role in surviving high temperatures for Ca. Accumulibacter. Ambiguous clade identity was observed for newly recovered genomes (SCELSE-9 and SCELSE-10). Five machine learning models were developed using orthogroups as input features. Prediction results suggested that they belong to a new clade (IIK). The phylogeny of Ca. Accumulibacter was re-evaluated based on the laterally derived polyphosphokinase 2 gene, showing improved resolution in differentiating different clades.
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Affiliation(s)
- Xiaojing Xie
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xuhan Deng
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Jinling Chen
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Liping Chen
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Jing Yuan
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Hang Chen
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Chaohai Wei
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou 510006, China
| | - Xianghui Liu
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore
| | - Guanglei Qiu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou 510006, China
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China
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Zhang H, Hu W, Liu R, Bartlam M, Wang Y. Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes. Environ Microbiol 2023; 25:3703-3718. [PMID: 37964717 DOI: 10.1111/1462-2920.16539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023]
Abstract
Planktonic bacteria can be grouped into 'high nucleic acid content (HNA) bacteria' and 'low nucleic acid content (LNA) bacteria.' Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell-1 ) than the continuous-treated LNA (0.00014, 0.00014 ng cell-1 ), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.
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Affiliation(s)
- Hui Zhang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Wei Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Ruidan Liu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Mark Bartlam
- College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Yingying Wang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
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6
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Thi Quynh Le H, Yeol Lee E. Methanotrophs: Metabolic versatility from utilization of methane to multi-carbon sources and perspectives on current and future applications. BIORESOURCE TECHNOLOGY 2023:129296. [PMID: 37302766 DOI: 10.1016/j.biortech.2023.129296] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/29/2023] [Accepted: 06/07/2023] [Indexed: 06/13/2023]
Abstract
The development of biorefineries for a sustainable bioeconomy has been driven by the concept of utilizing environmentally friendly and cost-effective renewable energy sources. Methanotrophic bacteria with a unique capacity to utilize methane as a carbon and energy source can serve as outstanding biocatalysts to develop C1 bioconversion technology. By establishing the utilization of diverse multi-carbon sources, integrated biorefinery platforms can be created for the concept of the circular bioeconomy. An understanding of physiology and metabolism could help to overcome challenges for biomanufacturing. This review summaries fundamental gaps for methane oxidation and the capability to utilize multi-carbon sources in methanotrophic bacteria. Subsequently, breakthroughs and challenges in harnessing methanotrophs as robust microbial chassis for industrial biotechnology were compiled and overviewed. Finally, capabilities to exploit the inherent advantages of methanotrophs to synthesize various target products in higher titers are proposed.
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Affiliation(s)
- Hoa Thi Quynh Le
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, Republic of Korea.
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7
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Cre/ lox-Mediated CRISPRi Library Reveals Core Genome of a Type I Methanotroph Methylotuvimicrobium buryatense 5GB1C. Appl Environ Microbiol 2023; 89:e0188322. [PMID: 36622175 PMCID: PMC9888281 DOI: 10.1128/aem.01883-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Methanotrophs play key roles in global methane cycling and are promising platforms for methane bioconversion. However, major gaps existing in fundamental knowledge undermines understanding of these methane-consuming microorganisms. To associate genes with a phenotype at the genome-wide level, we developed a Cre/lox-mediated method for constructing a large-scale CRISPRi library in a model methanotroph Methylotuvimicrobium buryatense 5GB1C. The efficiency of this Cre mediated integration method was up to a level of 105 CFU/μg DNA. Targeting 4,100 predicted protein-coding genes, our CRISPRi pooled screening uncovered 788 core genes for the growth of strain 5GB1C using methane. The core genes are highly consistent with the gene knockout results, indicating the reliability of the CRISPRi screen. Insights from the core genes include that annotated isozymes generally exist in metabolic pathways and many core genes are hypothetical genes. This work not only provides functional genomic data for both fundamental research and metabolic engineering of methanotrophs, but also offers a method for CRISPRi library construction. IMPORTANCE Due to their key role in methane cycling and their industrial potential, methanotrophs have drawn increasing attention. Genome-wide experimental approaches for gene-phenotype mapping accelerate our understanding and engineering of a bacterium. However, these approaches are still unavailable in methanotrophs. This work has two significant implications. First, the core genes identified here provide functional genetic basics for complete reconstruction of the metabolic network and afford more clues for knowledge gaps. Second, the Cre-mediated knock-in method developed in this work enables large-scale DNA library construction in methanotrophs; the CRISPRi library can be used to screen the genes associated with special culture conditions.
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Le HTQ, Lee EY. Insights into C1 and C3 assimilation pathways in type I methanotrophic bacterium from co-production of 1,2-propanediol and lactate. BIORESOURCE TECHNOLOGY 2022; 365:128172. [PMID: 36279980 DOI: 10.1016/j.biortech.2022.128172] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Methanotrophic bacteria are attractive hosts for mining metabolic pathways of C1 assimilation to produce value-added products. Herein, the type I methanotroph Methylotuvimicrobium alcaliphilum 20Z was employed to explore the carbon flux from methane and methanol via the EMP pathway to produce 1,2-propanediol (1,2-PDO). The production of 1,2-PDO on methane was found to be mainly restricted by the lower carbon flux toward the EMP pathway. The co-utilization of C1 substrates and glycerol (C3) could contribute to enhance 1,2-PDO. Lactate was co-produced in much higher amounts than 1,2-PDO. This unexpected product was probably derived from lactaldehyde by inherent aldehyde dehydrogenases. The 1,2-PDO production without increased accumulation of lactate was observed via establishing the acetol-based pathway by propane utilization with the overexpression of pmoD. This is the first study to provide experimental insights into the operation of metabolic routes for 1,2-PDO and lactate co-production from C1 and C3 compounds in methanotrophs.
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Affiliation(s)
- Hoa Thi Quynh Le
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, Republic of Korea.
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Abstract
Microbes with the capacity to use methane (CH4) as a carbon source (methanotrophs) have significant potential for the bioconversion of CH4-containing natural gas and anaerobic digestion-derived biogas to high value products. These organisms also play a vital role in the biogeochemical cycling of atmospheric CH4 by serving as the only known biological sink of this gas in terrestrial and aquatic ecosystems. Much is known regarding the enzymes and central metabolic pathways mediating CH4 utilization in these bacteria. However, large fundamental knowledge gaps exist regarding methanotroph physiology and responses to environmental stimuli, primarily due to a lack of efficient molecular tools to probe gene-function relationships. In this chapter, we describe several recently developed genetic tools and optimized genome editing methods that can be used for methanotroph metabolic engineering and to probe metabolic and physiological governing mechanisms in these unique bacteria.
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Affiliation(s)
- Sreemoye Nath
- Department of Biological Sciences, University of North Texas, Denton, TX, USA
- BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Jessica M Henard
- BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Calvin A Henard
- Department of Biological Sciences, University of North Texas, Denton, TX, USA.
- BioDiscovery Institute, University of North Texas, Denton, TX, USA.
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10
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Wilson EH, Groom JD, Sarfatis MC, Ford SM, Lidstrom ME, Beck DAC. A Computational Framework for Identifying Promoter Sequences in Nonmodel Organisms Using RNA-seq Data Sets. ACS Synth Biol 2021; 10:1394-1405. [PMID: 33988977 DOI: 10.1021/acssynbio.1c00017] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Engineering microorganisms into biological factories that convert renewable feedstocks into valuable materials is a major goal of synthetic biology; however, for many nonmodel organisms, we do not yet have the genetic tools, such as suites of strong promoters, necessary to effectively engineer them. In this work, we developed a computational framework that can leverage standard RNA-seq data sets to identify sets of constitutive, strongly expressed genes and predict strong promoter signals within their upstream regions. The framework was applied to a diverse collection of RNA-seq data measured for the methanotroph Methylotuvimicrobium buryatense 5GB1 and identified 25 genes that were constitutively, strongly expressed across 12 experimental conditions. For each gene, the framework predicted short (27-30 nucleotide) sequences as candidate promoters and derived -35 and -10 consensus promoter motifs (TTGACA and TATAAT, respectively) for strong expression in M. buryatense. This consensus closely matches the canonical E. coli sigma-70 motif and was found to be enriched in promoter regions of the genome. A subset of promoter predictions was experimentally validated in a XylE reporter assay, including the consensus promoter, which showed high expression. The pmoC, pqqA, and ssrA promoter predictions were additionally screened in an experiment that scrambled the -35 and -10 signal sequences, confirming that transcription initiation was disrupted when these specific regions of the predicted sequence were altered. These results indicate that the computational framework can make biologically meaningful promoter predictions and identify key pieces of regulatory systems that can serve as foundational tools for engineering diverse microorganisms for biomolecule production.
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Affiliation(s)
- Erin H. Wilson
- The Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Joseph D. Groom
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - M. Claire Sarfatis
- Department of Microbiology, University of Washington, Seattle, Washington 98195, United States
| | - Stephanie M. Ford
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Mary E. Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
- Department of Microbiology, University of Washington, Seattle, Washington 98195, United States
| | - David A. C. Beck
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
- eScience Institute, University of Washington, Seattle, Washington 98195, United States
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11
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Transcriptomic and Metabolomic Responses to Carbon and Nitrogen Sources in Methylomicrobium album BG8. Appl Environ Microbiol 2021; 87:e0038521. [PMID: 33893121 DOI: 10.1128/aem.00385-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methanotrophs use methane as their sole carbon and energy source and represent an attractive platform for converting single-carbon feedstocks into value-added compounds. Optimizing these species for biotechnological applications involves choosing an optimal growth substrate based on an understanding of cellular responses to different nutrients. Although many studies of methanotrophs have examined growth rate, yield, and central carbon flux in cultures grown with different carbon and nitrogen sources, few studies have examined more global cellular responses to different media. Here, we evaluated global transcriptomic and metabolomic profiles of Methylomicrobium album BG8 when grown with methane or methanol as the carbon source and nitrate or ammonium as the nitrogen source. We identified five key physiological changes during growth on methanol: M. album BG8 cultures upregulated transcripts for the Entner-Doudoroff and pentose phosphate pathways for sugar catabolism, produced more ribosomes, remodeled the phospholipid membrane, activated various stress response systems, and upregulated glutathione-dependent formaldehyde detoxification. When using ammonium, M. album BG8 upregulated hydroxylamine dehydrogenase (haoAB) and overall central metabolic activity, whereas when using nitrate, cultures upregulated genes for nitrate assimilation and conversion. Overall, we identified several nutrient source-specific responses that could provide a valuable basis for future research on the biotechnological optimization of these species. IMPORTANCE Methanotrophs are gaining increasing interest for their biotechnological potential to convert single-carbon compounds into value-added products such as industrial chemicals, fuels, and bioplastics. Optimizing these species for biotechnological applications requires a detailed understanding of how cellular activity and metabolism vary across different growth substrates. Although each of the two most commonly used carbon sources (methane or methanol) and nitrogen sources (ammonium or nitrate) in methanotroph growth media have well-described advantages and disadvantages in an industrial context, their effects on global cellular activity remain poorly characterized. Here, we comprehensively describe the transcriptomic and metabolomic changes that characterize the growth of an industrially promising methanotroph strain on multiple combinations of carbon and nitrogen sources. Our results represent a more holistic evaluation of cellular activity than previous studies of core metabolic pathways and provide a valuable basis for the future biotechnological optimization of these species.
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