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Jun-ru Cui - One of the best experts on this subject based on the ideXlab platform.
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efficient immobilization of whole cells of Methylomonas sp strain gyj3 by sol gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Efficient immobilization of whole cells of Methylomonas sp. strain GYJ3 by sol–gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Epoxypropane biosynthesis by Methylomonas sp. GYJ3: batch and continuous studies
World Journal of Microbiology and Biotechnology, 2002Co-Authors: Jia-ying Xin, Jianbo Chen, Jun-ru Cui, Li-min Zhu, Chun-gu XiaAbstract:Methylomonas sp. GYJ3 is a methanotrophic bacterium containing methane monooxygenase (MMO), which catalyses the epoxidation of propene to epoxypropane. In this study, the cell suspension of Methylomonas sp. GYJ3 has been used for epoxypropane biosynthesis from propene. When propene is epoxidized, the product epoxypropane is not further metabolized and accumulates extracellularly. Unfortunately, continuous production of epoxypropane is usually difficult due to exhaustion of reductant and the accumulation of toxic products. Hence, in order to address these problems, batch experiments were performed to explore the possibility of producing epoxypropane by a co-oxidation process. Methane was chosen as the most suitable electron-donating co-substrate since it did not result in molecular toxicity and provided abundant reductant for epoxidation. It was found that the maximum production of epoxypropane occurred in an atmosphere of 30% methane. Batch experiments also indicated that continuous removal of product was necessary to overcome the inhibition of epoxypropane. In continuous experiments, optimum mixed gaseous substrates were continuously circulated through the stirred tank bioreactor to remove product from the cell suspension. Initial epoxypropane productivity was 268 μmol/day. The bioreactor has been allowed to operate continuously for 12 days without obvious loss of epoxypropane productivity, and more than 96% of initial MMO activity was retained.
Mary E. Lidstrom - One of the best experts on this subject based on the ideXlab platform.
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Real-time detection of actively metabolizing microbes by redox sensing as applied to methylotroph populations in Lake Washington
The ISME Journal, 2008Co-Authors: Marina G. Kalyuzhnaya, Mary E. Lidstrom, Ludmila ChistoserdovaAbstract:Redox sensor green (RSG), a novel fluorescent dye from Invitrogen was employed as a tool for real-time detection of microbes metabolically active in situ , in combination with flow cytometry and cell sorting. Lake Washington sediment, an environment known for high rates of methane oxidation, was used as a model, and methylotrophs were targeted as a functional group. We first tested and optimized the performance of the dye with pure methylotroph cultures. Most cells in actively growing cultures were positive for staining, whereas in starved cultures, few cells fluoresced. However, starved cells could be activated by addition of substrate. High numbers of fluorescing cells were observed in a Lake Washington sediment sample, and activation of subpopulations of cells was demonstrated in response to methane, methanol, methylamine and formaldehyde. The fraction of the population activated by methane was investigated in more detail, by phylogenetic profiling. This approach showed that the major responding species were the Methylomonas species, previously isolated from the site, and Methylobacter species that have not yet been cultivated from Lake Washington. In addition, from the methane-stimulated fraction, uncultivated bacterial sequences were obtained that belonged to unclassified Deltaproteobacteria, unclassified Verrucomicrobiles and unclassified Acidobacteria, suggesting that these microbes may also be involved in methane metabolism. The approach was further tested for its utility in facilitating enrichment for functional types that possess specific metabolic activities but resist cultivation. It was demonstrated that in enrichment cultures inoculated with cells that were sorted after stimulation with methane, Methylobacter sequences could be detected, whereas in enrichment cultures inoculated by randomly sorted cells, Methylomonas species quickly outcompeted all other types.
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Analysis of sMMO-containing type I methanotrophs in Lake Washington sediment.
Environmental Microbiology, 2002Co-Authors: Ann J Auman, Mary E. LidstromAbstract:Summary Methane-oxidizing bacteria (methanotrophs) containing soluble methane monooxygenase (sMMO) are of interest in natural environments due to the high co-metabolic activity of this enzyme with contaminants such as trichloroethylene. We have analysed sMMO-containing methanotrophs in sediment from a freshwater lake. Environmental clone banks for a gene encoding a diagnostic sMMO subunit (mmoX) were generated using DNA extracted from Lake Washington sediment and subjected to RFLP analysis. Representatives from the six RFLP groups were cloned and sequenced, and all were found to group with Type I Methylomonas mmoX, although a majority were divergent from known Methylomonas mmoX sequences. Direct hybridization of Lake Washington sediment DNA was carried out using a series of sMMO- and Methylomonas-specific probes to assess the significance of these sMMO-containing Methylomonas-like strains in the sediment. The total sMMO-containing population and the sMMO-containing Methylomonas-like population were estimated to be similar to previous estimates for total methanotrophs and Type I methanotrophs. These results suggest that the major methanotrophic population in Lake Washington sediment consists of sMMO-containing Methylomonas-like (Type I) methanotrophs. The whole-cell TCE degradation kinetics of such a strain, LW15, isolated from this environment, were determined and found to be similar to values reported for other sMMO-containing methanotrophs. The numerical significance of sMMO-containing Methylomonas-like methanotrophs in a mesotrophic lake environment suggests that these methanotrophs may play an important role in methanotroph-mediated transformations, including co-metabolism of halogenated solvents, in natural environments.
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Methanol oxidation genes in the marine methanotroph Methylomonas sp. strain A4.
Journal of bacteriology, 1993Co-Authors: Daryle Waechter-brulla, Alan A. Dispirito, Ludmila Chistoserdova, Mary E. LidstromAbstract:Methanol dehydrogenase has been purified from the type I marine methanotroph Methylomonas sp. strain A4 and found to be similar to other methanol dehydrogenase enzymes in subunit composition, molecular mass, and N-terminal sequence of the two subunits. A heterologous gene probe and a homologous oligonucleotide have been used to identify a DNA fragment from Methylomonas sp. strain A4 which contains moxF, the gene encoding the large subunit of methanol dehydrogenase. Protein expression experiments with Escherichia coli, immunoblotting of expression extracts, and partial DNA sequence determination have confirmed the presence of moxF on this DNA fragment. In addition, expression and immunoblot experiments have shown the presence of the genes for the small subunit of methanol dehydrogenase (moxI) and for the methanol dehydrogenase-specific cytochrome c (moxG). The moxG gene product has been shown to be cytochrome c552. The expression experiments have also shown that two other genes are present on this DNA fragment, and our evidence suggests that these are the homologs of moxJ and moxR, whose functions are unknown. Our data suggest that the order of these genes in Methylomonas sp. strain A4 is moxFJGIR, the same as in the facultative methylotrophs. The transcriptional start site for moxF was mapped. The sequence 5' to the transcriptional start does not resemble other promoter sequences, including the putative moxF promoter sequence of facultative methylotrophs. These results suggest that although the order of these genes and the N-terminal amino acid sequence of MoxF and MoxI are conserved between distantly related methylotrophs, the promoters for this gene cluster differ substantially.
Jianbo Chen - One of the best experts on this subject based on the ideXlab platform.
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efficient immobilization of whole cells of Methylomonas sp strain gyj3 by sol gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Efficient immobilization of whole cells of Methylomonas sp. strain GYJ3 by sol–gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Epoxypropane biosynthesis by Methylomonas sp. GYJ3: batch and continuous studies
World Journal of Microbiology and Biotechnology, 2002Co-Authors: Jia-ying Xin, Jianbo Chen, Jun-ru Cui, Li-min Zhu, Chun-gu XiaAbstract:Methylomonas sp. GYJ3 is a methanotrophic bacterium containing methane monooxygenase (MMO), which catalyses the epoxidation of propene to epoxypropane. In this study, the cell suspension of Methylomonas sp. GYJ3 has been used for epoxypropane biosynthesis from propene. When propene is epoxidized, the product epoxypropane is not further metabolized and accumulates extracellularly. Unfortunately, continuous production of epoxypropane is usually difficult due to exhaustion of reductant and the accumulation of toxic products. Hence, in order to address these problems, batch experiments were performed to explore the possibility of producing epoxypropane by a co-oxidation process. Methane was chosen as the most suitable electron-donating co-substrate since it did not result in molecular toxicity and provided abundant reductant for epoxidation. It was found that the maximum production of epoxypropane occurred in an atmosphere of 30% methane. Batch experiments also indicated that continuous removal of product was necessary to overcome the inhibition of epoxypropane. In continuous experiments, optimum mixed gaseous substrates were continuously circulated through the stirred tank bioreactor to remove product from the cell suspension. Initial epoxypropane productivity was 268 μmol/day. The bioreactor has been allowed to operate continuously for 12 days without obvious loss of epoxypropane productivity, and more than 96% of initial MMO activity was retained.
Eun Yeol Lee - One of the best experts on this subject based on the ideXlab platform.
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Metabolic engineering of the type I methanotroph Methylomonas sp. DH-1 for production of succinate from methane.
Metabolic engineering, 2019Co-Authors: Diep Thi Ngoc Nguyen, Susila Hadiyati, Min-sik Kim, Ok Kyung Lee, Azka Nur Affifah, Eun Yeol LeeAbstract:Methane-utilizing methanotrophs are fascinating systems for methane bioconversion. Methylomonas sp. DH-1, a novel type I methanotroph isolated from brewery sludge, has been evaluated as a promising candidate for an industrial bio-catalyst. Succinate has been considered one of the top building block chemicals for the agricultural, food, and pharmaceutical industries. In this study, Methylomonas sp. DH-1 was engineered to accumulate succinate as a desired product. The TCA cycle and enzymes diverting carbon flux to acetate or formate were modified or deleted to improve succinate productivity. By deleting succinate dehydrogenase (sdh) in the TCA cycle, succinate production increased dramatically ∼10 times compared to that of the wild type. In addition, the maximum succinate titer of ∼134 mg/L (DS-GL) was achieved by integrating glyoxylate shunt enzymes from the E. coli MG1655 strain. Pyruvate formate lyase (pfl) and acetate kinase-phosphotransacetylase (ack-pta) genes were disrupted to further concentrate carbon flux to the TCA cycle. However, these additional disruptions of competitive pathways did not affect cell growth or succinate production positively. The mutant strain DS-GL, which showed the best succinate production, was grown in a fed-batch bioreactor, and higher cell growth and succinate production (∼195 mg/L succinate with 0.0789 g-succinate/g-methane yield) were achieved. In this study, we demonstrated a novel platform for microbial conversion of methane to succinate using methanotroph.
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Functional Analysis of Methylomonas sp. DH-1 Genome as a Promising Biocatalyst for Bioconversion of Methane to Valuable Chemicals
Catalysts, 2018Co-Authors: Anh Dzung Nguyen, In Hwang, Ok Jae Lee, Dong Hur, Young Ho Jeon, Susila Hadiyati, Min-sik Kim, Sung Yoon, Haeyoung Jeong, Eun Yeol LeeAbstract:Methylomonas sp. DH-1, newly isolated from the activated sludge of a brewery plant, has been used as a promising biocatalytic platform for the conversion of methane to value-added chemicals. Methylomonas sp. DH-1 can efficiently convert methane and propane into methanol and acetone with a specific productivity of 4.31 and 0.14 mmol/g cell/h, the highest values ever reported, respectively. Here, we present the complete genome sequence of Methylomonas sp. DH-1 which consists of a 4.86 Mb chromosome and a 278 kb plasmid. The existence of a set of genes related to one-carbon metabolism and various secondary metabolite biosynthetic pathways including carotenoid pathways were identified. Interestingly, Methylomonas sp. DH-1 possesses not only the genes of the ribulose monophosphate cycle for type I methanotrophs but also the genes of the serine cycle for type II. Methylomonas sp. DH-1 accumulated 80 mM succinate from methane under aerobic conditions, because DH-1 has 2-oxoglutarate dehydrogenase activity and the ability to operate the full TCA cycle. Availability of the complete genome sequence of Methylomonas sp. DH-1 enables further investigations on the metabolic engineering of this strain for the production of value-added chemicals from methane.
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Selective bio-oxidation of propane to acetone using methane-oxidizing Methylomonas sp. DH-1.
Journal of industrial microbiology & biotechnology, 2017Co-Authors: Dong Hoon Hur, Thu Thi Nguyen, Donghyuk Kim, Eun Yeol LeeAbstract:Propane is the major component of liquefied petroleum gas (LPG). Nowadays, the use of LPG is decreasing, and thus utilization of propane as a chemical feedstock is in need of development. An efficient biological conversion of propane to acetone using a methanotrophic whole cell as the biocatalyst was proposed and investigated. A bio-oxidation pathway of propane to acetone in Methylomonas sp. DH-1 was analyzed by gene expression profiling via RNA sequencing. Propane was oxidized to 2-propanol by particulate methane monooxygenase and subsequently to acetone by methanol dehydrogenases. Methylomonas sp. DH-1 was deficient in acetone-converting enzymes and thus accumulated acetone in the absence of any enzyme inhibition. The maximum accumulation, average productivity and specific productivity of acetone were 16.62 mM, 0.678 mM/h and 0.141 mmol/g cell/h, respectively, under the optimized conditions. Our study demonstrates a novel method for the bioconversion of propane to acetone using methanotrophs under mild reaction condition.
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Highly efficient bioconversion of methane to methanol using a novel type I Methylomonas sp. DH-1 newly isolated from brewery waste sludge
Journal of Chemical Technology & Biotechnology, 2016Co-Authors: Dong Hoon Hur, Eun Yeol LeeAbstract:Background Methane is the major component of natural and shale gas. Methane can be converted into methanol via a bioprocess using methanotrophs, and methanol is a valuable chemical feedstock for the production of value-added chemicals. This work demonstrates highly effective bioconversion of methane to methanol using a newly isolated novel methanotroph, Methylomonas sp. DH-1. Results A novel methanotroph strain was isolated from activated sludge from a brewery plant and characterized using phylogenetic analysis, electron microscopy and chemotaxonomic analysis. This aerobic, Gram-negative, non-motile rod-shaped type I methanotroph was designated as Methylomonas sp. DH-1. The growth condition of Methylomonas sp. DH-1 and batch methane-to-methanol bioconversion conditions such as methane concentration, pH, biocatalyst loading, concentration of formate and MDH inhibitor were analyzed and optimized. Methanol was produced from methane with a 1.340 g L−1 titer, a 0.332 g L−1 h−1 volumetric conversion rate and a 0.0752 g g−1 cell h−1 specific methanol conversion rate. Conclusion It was demonstrated that isolation and application of a new methanotroph strain is a practical way of improving bioconversion efficiency in the conversion of methane to methanol. Moreover, one promising feature of Methylomonas sp. DH-1 for methanol production was its extremely high tolerance to methanol up to 7%(v/v), which is advantageous for high-titer methanol production. © 2016 Society of Chemical Industry
Jia-ying Xin - One of the best experts on this subject based on the ideXlab platform.
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efficient immobilization of whole cells of Methylomonas sp strain gyj3 by sol gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Efficient immobilization of whole cells of Methylomonas sp. strain GYJ3 by sol–gel entrapment
Journal of Molecular Catalysis B-enzymatic, 2004Co-Authors: Jianbo Chen, Jia-ying Xin, Chun-gu Xia, Jun-ru CuiAbstract:Abstract The whole cells of Methanotrophic bacteria Methylomonas sp. strain GYJ3 immobilized by the sol–gel technique was investigated in the present work. After the cells were immobilized by entrapment in sodium silicate sol–gel matrix, a higher activity for propylene epoxidation were observed at a common loading amount. In a batch reaction system, the immobilized cells can be repeatedly used for more than 25 times and no significant loss of the activity was found. The activity was well preserved when the immobilized cells were stored at 4 °C for 45 days. Determination of optimal reaction conditions showed that the immobilized cells took on increased activity at a higher pH and temperature. However, the cells entrapped in methyltrimethoxysilane (MTMS) gel matrix gave a lower activity as compared to that of the free cells. Our experimental results indicate that the sol–gel entrapment based on silica matrixes was a simple, efficient and cost-efficient method for the immobilization the whole cells of Methylomonas sp. strain GYJ3 cells.
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Epoxypropane biosynthesis by Methylomonas sp. GYJ3: batch and continuous studies
World Journal of Microbiology and Biotechnology, 2002Co-Authors: Jia-ying Xin, Jianbo Chen, Jun-ru Cui, Li-min Zhu, Chun-gu XiaAbstract:Methylomonas sp. GYJ3 is a methanotrophic bacterium containing methane monooxygenase (MMO), which catalyses the epoxidation of propene to epoxypropane. In this study, the cell suspension of Methylomonas sp. GYJ3 has been used for epoxypropane biosynthesis from propene. When propene is epoxidized, the product epoxypropane is not further metabolized and accumulates extracellularly. Unfortunately, continuous production of epoxypropane is usually difficult due to exhaustion of reductant and the accumulation of toxic products. Hence, in order to address these problems, batch experiments were performed to explore the possibility of producing epoxypropane by a co-oxidation process. Methane was chosen as the most suitable electron-donating co-substrate since it did not result in molecular toxicity and provided abundant reductant for epoxidation. It was found that the maximum production of epoxypropane occurred in an atmosphere of 30% methane. Batch experiments also indicated that continuous removal of product was necessary to overcome the inhibition of epoxypropane. In continuous experiments, optimum mixed gaseous substrates were continuously circulated through the stirred tank bioreactor to remove product from the cell suspension. Initial epoxypropane productivity was 268 μmol/day. The bioreactor has been allowed to operate continuously for 12 days without obvious loss of epoxypropane productivity, and more than 96% of initial MMO activity was retained.