1
|
Zhu Y, Koo CW, Cassidy CK, Spink MC, Ni T, Zanetti-Domingues LC, Bateman B, Martin-Fernandez ML, Shen J, Sheng Y, Song Y, Yang Z, Rosenzweig AC, Zhang P. Structure and activity of particulate methane monooxygenase arrays in methanotrophs. Nat Commun 2022; 13:5221. [PMID: 36064719 PMCID: PMC9445010 DOI: 10.1038/s41467-022-32752-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/16/2022] [Indexed: 01/29/2023] Open
Abstract
Methane-oxidizing bacteria play a central role in greenhouse gas mitigation and have potential applications in biomanufacturing. Their primary metabolic enzyme, particulate methane monooxygenase (pMMO), is housed in copper-induced intracytoplasmic membranes (ICMs), of which the function and biogenesis are not known. We show by serial cryo-focused ion beam (cryoFIB) milling/scanning electron microscope (SEM) volume imaging and lamellae-based cellular cryo-electron tomography (cryoET) that these ICMs are derived from the inner cell membrane. The pMMO trimer, resolved by cryoET and subtomogram averaging to 4.8 Å in the ICM, forms higher-order hexagonal arrays in intact cells. Array formation correlates with increased enzymatic activity, highlighting the importance of studying the enzyme in its native environment. These findings also demonstrate the power of cryoET to structurally characterize native membrane enzymes in the cellular context.
Collapse
Affiliation(s)
- Yanan Zhu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Christopher W Koo
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Matthew C Spink
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Tao Ni
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Benji Bateman
- Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Juan Shen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Yuewen Sheng
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Yun Song
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Zhengyi Yang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- Imaging Centre, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA.
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK.
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK.
| |
Collapse
|
2
|
Wang S, Liu Q, Li J, Wang Z. Methane in wastewater treatment plants: status, characteristics, and bioconversion feasibility by methane oxidizing bacteria for high value-added chemicals production and wastewater treatment. WATER RESEARCH 2021; 198:117122. [PMID: 33865027 DOI: 10.1016/j.watres.2021.117122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/23/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Methane is a type of renewable fuel that can generate many types of high value-added chemicals, however, besides heat and power production, there is little methane utilization in most of the wastewater treatment plants (WWTPs) all round the world currently. In this review, the status of methane production performance from WWTPs was firstly investigated. Subsequently, based on the identification and classification of methane oxidizing bacteria (MOB), the key enzymes and metabolic pathway of MOB were presented in depth. Then the production, extraction and purification process of high value-added chemicals, including methanol, ectoine, biofuel, bioplastic, methane protein and extracellular polysaccharides, were introduced in detail, which was conducive to understand the bioconversion process of methane. Finally, the use of methane in wastewater treatment process, including nitrogen removal, emerging contaminants removal as well as resource recovery was extensively explored. These findings could provide guidance in the development of sustainable economy and environment, and facilitate biological methane conversion by using MOB in further attempts.
Collapse
Affiliation(s)
- Shuo Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Wuxi 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou 215009, China
| | - Qixin Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Wuxi 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou 215009, China.
| | - Zhiwu Wang
- Department of Civil and Environmental Engineering, Virginia Tech, Manassas, VA 20110, USA.
| |
Collapse
|
3
|
Tsapekos P, Zhu X, Pallis E, Angelidaki I. Proteinaceous methanotrophs for feed additive using biowaste as carbon and nutrients source. BIORESOURCE TECHNOLOGY 2020; 313:123646. [PMID: 32535520 DOI: 10.1016/j.biortech.2020.123646] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
To achieve a sustainable production of food and feed production, inexpensive carbon and nutrient sources are needed. In the present study, biologically upgraded biogas is coupled with electrochemically extracted nitrogen from digested biowaste to cultivate mixed methanotrophs as protein source. Results showed that an increase from less than 5 μgCu2+/L to 100 μgCu2+/L increased the biomass production by 41%. Microbial analysis revealed that the dominated Methylomonas spp. followed by Methylophilus spp. created a specialized community for high CH4 assimilation. Moreover, duplicate semi-continuous fermenters run for 120 days validating the efficiency of alternative carbon and nitrogen feedstocks at long-term operation. As for dry cell weight (DCW) production, more than 2.5 g-DCW/L were produced using biologically upgraded biogas and electrochemically extracted nitrogen. Furthermore, the protein content and amino acid profile (>50% of DCW) demonstrated that the microbial biomass pose the characteristics to be used as animal feed additive.
Collapse
Affiliation(s)
- Panagiotis Tsapekos
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
| | - Xinyu Zhu
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | - Evangelos Pallis
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| |
Collapse
|
4
|
Wang S, An Z, Wang ZW. Bioconversion of methane to chemicals and fuels by methane-oxidizing bacteria. ADVANCES IN BIOENERGY 2020. [DOI: 10.1016/bs.aibe.2020.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
5
|
DiSpirito AA, Semrau JD, Murrell JC, Gallagher WH, Dennison C, Vuilleumier S. Methanobactin and the Link between Copper and Bacterial Methane Oxidation. Microbiol Mol Biol Rev 2016; 80:387-409. [PMID: 26984926 PMCID: PMC4867365 DOI: 10.1128/mmbr.00058-15] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Methanobactins (mbs) are low-molecular-mass (<1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu(2+) to Cu(1+). In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs.
Collapse
Affiliation(s)
- Alan A DiSpirito
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Jeremy D Semrau
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - J Colin Murrell
- Earth and Life Systems Alliance, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
| | - Warren H Gallagher
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin, USA
| | - Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Stéphane Vuilleumier
- Department of Microbiology, Genomics and the Environment, UMR 7156 UNISTRA-CNRS, Université de Strasbourg, Strasbourg, France
| |
Collapse
|
6
|
Gilman A, Laurens LM, Puri AW, Chu F, Pienkos PT, Lidstrom ME. Bioreactor performance parameters for an industrially-promising methanotroph Methylomicrobium buryatense 5GB1. Microb Cell Fact 2015; 14:182. [PMID: 26572866 PMCID: PMC4647623 DOI: 10.1186/s12934-015-0372-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/29/2015] [Indexed: 11/22/2022] Open
Abstract
Background Methane is a feedstock of interest for the future, both from natural gas and from renewable biogas sources. Methanotrophic bacteria have the potential to enable commercial methane bioconversion to value-added products such as fuels and chemicals. A strain of interest for such applications is Methylomicrobium buryatense 5GB1, due to its robust growth characteristics. However, to take advantage of the potential of this methanotroph, it is important to generate comprehensive bioreactor-based datasets for different growth conditions to compare bioprocess parameters. Results Datasets of growth parameters, gas utilization rates, and products (total biomass, extracted fatty acids, glycogen, excreted acids) were obtained for cultures of M. buryatense 5GB1 grown in continuous culture under methane limitation and O2 limitation conditions. Additionally, experiments were performed involving unrestricted batch growth conditions with both methane and methanol as substrate. All four growth conditions show significant differences. The most notable changes are the high glycogen content and high formate excretion for cells grown on methanol (batch), and high O2:CH4 utilization ratio for cells grown under methane limitation. Conclusions The results presented here represent the most comprehensive published bioreactor datasets for a gamma-proteobacterial methanotroph. This information shows that metabolism by M. buryatense 5GB1 differs significantly for each of the four conditions tested. O2 limitation resulted in the lowest relative O2 demand and fed-batch growth on methane the highest. Future studies are needed to understand the metabolic basis of these differences. However, these results suggest that both batch and continuous culture conditions have specific advantages, depending on the product of interest. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0372-8) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Alexey Gilman
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Lieve M Laurens
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - Aaron W Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Frances Chu
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Philip T Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA. .,Department of Microbiology, University of Washington, Seattle, WA, 98195, USA.
| |
Collapse
|
7
|
Abstract
Methanotrophs, cells that consume methane (CH(4)) as their sole source of carbon and energy, play key roles in the global carbon cycle, including controlling anthropogenic and natural emissions of CH(4), the second-most important greenhouse gas after carbon dioxide. These cells have also been widely used for bioremediation of chlorinated solvents, and help sustain diverse microbial communities as well as higher organisms through the conversion of CH(4) to complex organic compounds (e.g. in deep ocean and subterranean environments with substantial CH(4) fluxes). It has been well-known for over 30 years that copper (Cu) plays a key role in the physiology and activity of methanotrophs, but it is only recently that we have begun to understand how these cells collect Cu, the role Cu plays in CH(4) oxidation by the particulate CH(4) monooxygenase, the effect of Cu on the proteome, and how Cu affects the ability of methanotrophs to oxidize different substrates. Here we summarize the current state of knowledge of the phylogeny, environmental distribution, and potential applications of methanotrophs for regional and global issues, as well as the role of Cu in regulating gene expression and proteome in these cells, its effects on enzymatic and whole-cell activity, and the novel Cu uptake system used by methanotrophs.
Collapse
Affiliation(s)
- Jeremy D Semrau
- Department of Civil and Environmental Engineering, The University of Michigan, Ann Arbor, MI, USA.
| | | | | |
Collapse
|
8
|
Kim HJ, Graham DW, DiSpirito AA, Alterman MA, Galeva N, Larive CK, Asunskis D, Sherwood PMA. Methanobactin, a copper-acquisition compound from methane-oxidizing bacteria. Science 2004; 305:1612-5. [PMID: 15361623 DOI: 10.1126/science.1098322] [Citation(s) in RCA: 218] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Siderophores are extracellular iron-binding compounds that mediate iron transport into many cells. We present evidence of analogous molecules for copper transport from methane-oxidizing bacteria, represented here by a small fluorescent chromopeptide (C45N12O14H62Cu, 1216 daltons) produced by Methylosinus trichosporium OB3b. The crystal structure of this compound, methanobactin, was resolved to 1.15 angstroms. It is composed of a tetrapeptide, a tripeptide, and several unusual moieties, including two 4-thionyl-5-hydroxy-imidazole chromophores that coordinate the copper, a pyrrolidine that confers a bend in the overall chain, and an amino-terminal isopropylester group. The copper coordination environment includes a dual nitrogen- and sulfur-donating system derived from the thionyl imidazolate moieties. Structural elucidation of this molecule has broad implications in terms of organo-copper chemistry, biological methane oxidation, and global carbon cycling.
Collapse
Affiliation(s)
- Hyung J Kim
- Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Choi DW, Kunz RC, Boyd ES, Semrau JD, Antholine WE, Han JI, Zahn JA, Boyd JM, de la Mora AM, DiSpirito AA. The membrane-associated methane monooxygenase (pMMO) and pMMO-NADH:quinone oxidoreductase complex from Methylococcus capsulatus Bath. J Bacteriol 2003; 185:5755-64. [PMID: 13129946 PMCID: PMC193963 DOI: 10.1128/jb.185.19.5755-5764.2003] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2003] [Accepted: 07/21/2003] [Indexed: 11/20/2022] Open
Abstract
Improvements in purification of membrane-associated methane monooxygenase (pMMO) have resulted in preparations of pMMO with activities more representative of physiological rates: i.e., >130 nmol.min(-1).mg of protein(-1). Altered culture and assay conditions, optimization of the detergent/protein ratio, and simplification of the purification procedure were responsible for the higher-activity preparations. Changes in the culture conditions focused on the rate of copper addition. To document the physiological events that occur during copper addition, cultures were initiated in medium with cells expressing soluble methane monooxygenase (sMMO) and then monitored for morphological changes, copper acquisition, fatty acid concentration, and pMMO and sMMO expression as the amended copper concentration was increased from 0 (approximately 0.3 microM) to 95 microM. The results demonstrate that copper not only regulates the metabolic switch between the two methane monooxygenases but also regulates the level of expression of the pMMO and the development of internal membranes. With respect to stabilization of cell-free pMMO activity, the highest cell-free pMMO activity was observed when copper addition exceeded maximal pMMO expression. Optimization of detergent/protein ratios and simplification of the purification procedure also contributed to the higher activity levels in purified pMMO preparations. Finally, the addition of the type 2 NADH:quinone oxidoreductase complex (NADH dehydrogenase [NDH]) from M. capsulatus Bath, along with NADH and duroquinol, to enzyme assays increased the activity of purified preparations. The NDH and NADH were added to maintain a high duroquinol/duroquinone ratio.
Collapse
Affiliation(s)
- Dong-W Choi
- Department of Biochemistry, Biophysics, and Molecular Biology, and Graduate Program in Microbiology, Iowa State University, Ames, Iowa 50011-3211, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
DiSpirito AA, Zahn JA, Graham DW, Kim HJ, Larive CK, Derrick TS, Cox CD, Taylor A. Copper-binding compounds from Methylosinus trichosporium OB3b. J Bacteriol 1998; 180:3606-13. [PMID: 9658004 PMCID: PMC107329 DOI: 10.1128/jb.180.14.3606-3613.1998] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Two copper-binding compounds/cofactors (CBCs) were isolated from the spent media of both the wild type and a constitutive soluble methane monooxygenase (sMMOC) mutant, PP319 (P. A. Phelps et al., Appl. Environ. Microbiol. 58:3701-3708, 1992), of Methylosinus trichosporium OB3b. Both CBCs are small polypeptides with molecular masses of 1,218 and 779 Da for CBC-L1 and CBC-L2, respectively. The amino acid sequence of CBC-L1 is S?MYPGS?M, and that of CBC-L2 is SPMP?S. Copper-free CBCs showed absorption maxima at 204, 275, 333, and 356 with shoulders at 222 and 400 nm. Copper-containing CBCs showed a broad absorption maximum at 245 nm. The low-temperature electron paramagnetic resonance (EPR) spectra of copper-containing CBC-L1 showed the presence of a copper center with an EPR splitting constant between those of type 1 and type 2 copper centers (g = 2.087, g = 2.42 G, A = 128 G). The EPR spectrum of CBC-L2 was more complex and showed two spectrally distinct copper centers. One signal can be attributed to a type 2 Cu2+ center (g = 2.073, g = 2.324 G, A = 144 G) which could be saturated at higher powers, while the second shows a broad, nearly isotropic signal near g = 2.063. In wild-type strains, the concentrations of CBCs in the spent media were highest in cells expressing the pMMO and stressed for copper. In contrast to wild-type strains, high concentrations of CBCs were observed in the extracellular fraction of the sMMOC mutants PP319 and PP359 regardless of the copper concentration in the culture medium.
Collapse
Affiliation(s)
- A A DiSpirito
- Department of Microbiology, Immunology, and Preventive Medicine, Iowa State University, Ames, Iowa 50011, USA.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Lontoh S, Semrau JD. Methane and Trichloroethylene Degradation by
Methylosinus trichosporium
OB3b Expressing Particulate Methane Monooxygenase. Appl Environ Microbiol 1998; 64:1106-14. [PMID: 16349516 PMCID: PMC106375 DOI: 10.1128/aem.64.3.1106-1114.1998] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
Whole-cell assays of methane and trichloroethylene (TCE) consumption have been performed on
Methylosinus trichosporium
OB3b expressing particulate methane monooxygenase (pMMO). From these assays it is apparent that varying the growth concentration of copper causes a change in the kinetics of methane and TCE degradation. For
M. trichosporium
OB3b, increasing the copper growth concentration from 2.5 to 20 μM caused the maximal degradation rate of methane (
V
max
) to decrease from 300 to 82 nmol of methane/min/mg of protein. The methane concentration at half the maximal degradation rate (
K
s
) also decreased from 62 to 8.3 μM. The pseudo-first-order rate constant for methane,
V
max
/
K
s
, doubled from 4.9 × 10
−3
to 9.9 × 10
−3
liters/min/mg of protein, however, as the growth concentration of copper increased from 2.5 to 20 μM. TCE degradation by
M. trichosporium
OB3b was also examined with varying copper and formate concentrations.
M. trichosporium
OB3b grown with 2.5 μM copper was unable to degrade TCE in both the absence and presence of an exogenous source of reducing equivalents in the form of formate. Cells grown with 20 μM copper, however, were able to degrade TCE regardless of whether formate was provided. Without formate the
V
max
for TCE was 2.5 nmol/min/mg of protein, while providing formate increased the
V
max
to 4.1 nmol/min/mg of protein. The affinity for TCE also increased with increasing copper, as seen by a change in
K
s
from 36 to 7.9 μM.
V
max
/
K
s
for TCE degradation by pMMO also increased from 6.9 × 10
−5
to 5.2 × 10
−4
liters/min/mg of protein with the addition of formate. From these whole-cell studies it is apparent that the amount of copper available is critical in determining the oxidation of substrates in methanotrophs that are expressing only pMMO.
Collapse
Affiliation(s)
- S Lontoh
- Department of Civil and Environmental Engineering, The University of Michigan, Ann Arbor, Michigan 48109-2125
| | | |
Collapse
|