• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.717-724
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• 2016

Methane (CH₄) is the most abundant component in natural gas. To reduce its harmful environmental effect as a greenhouse gas, CH₄ can be utilized as a low-cost feed for the synthesis of methanol by methanotrophs. In this study, several methanotrophs were examined for their ability to produce methanol from CH₄; including Methylocella silvestris, Methylocystis bryophila, Methyloferula stellata, and Methylomonas methanica. Among these methanotrophs, M. bryophila exhibited the highest methanol production. The optimum process parameters aided in significant enhancement of methanol production up to 4.63 mM. Maximum methanol production was observed at pH 6.8, 30℃, 175 rpm, 100 mM phosphate buffer, 50 mM MgCl₂ as a methanol dehydrogenase inhibitor, 50% CH₄ concentration, 24 h of incubation, and 9 mg of dry cell mass ml^-1 inoculum load, respectively. Optimization of the process parameters, screening of methanol dehydrogenase inhibitors, and supplementation with formate resulted in significant improvements in methanol production using M. bryophila. This report suggests, for the first time, the potential of using M. bryophila for industrial methanol production from CH₄.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.993-998
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• 1999

The concurrent production of methanol and dimethyl ether from carbon dioxide hydrogenation has been studied under various reaction conditions. First, the methanol synthesis was compared with the concurrent production method. For the methanol synthesis, the ternary mixed oxide catalyst (CuO/ZnO/Al2O3) was used and for the coproduction of methanol and dimethyl ether, silica-alumina was mixed with the methanol synthesis catalyst to be a hybrid catalyst. The results show that the co-production provides much higher per-pass yield than methanol synthesis even at very short contact time. The effects of temperature, contact time, pressure and catalyst hybrid ratio on the product yields and selectivities were also determined in the co-production.

• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1234-1241
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• 2016

Methanol is a versatile compound that can be biologically synthesized from methane (CH₄) by methanotrophs using a low energy-consuming and environment-friendly process. Methylocella tundrae is a type II methanotroph that can utilize CH₄ as a carbon and energy source. Methanol is produced in the first step of the metabolic pathway of methanotrophs and is further oxidized into formaldehyde. Several parameters must be optimized to achieve high methanol production. In this study, we optimized the production conditions and process parameters for methanol production. The optimum incubation time, substrate, pH, agitation rate, temperature, phosphate buffer and sodium formate concentration, and cell concentration were determined to be 24 h, 50% CH₄, pH 7, 150 rpm, 30℃, 100 mM and 50 mM, and 18 mg/ml, respectively. The optimization of these parameters significantly improved methanol production from 0.66 to 5.18 mM. The use of alginate-encapsulated cells resulted in enhanced methanol production stability and reusability of cells after five cycles of reuse under batch culture conditions.

• KSBB Journal
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• v.11 no.6
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• pp.642-648
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• 1996

The effects of EDTA(Ethylene diamine tetraacetic acid), Cu, temperature, and gas(methane and oxygen) composition on methanol production from methane with Methylosinus trichosporium were investigated. In this experiment EDTA was found to be a potential methanol dehydrogenase inhibitor since it causes methanol accumulation and 6mM was found to be optimum concentration of EDTA for methanol production. When Cu was added in culture media, the produced methanol concentration level was increased. Hence it is believed that Cu enhanced the particulate methane monooxygenase formation and consequently the addition of Cu could increase the methanol production from methane. In this experiment the optimum concentration of Cu was found to be 1mM for methanol production. When temperature was shifted down from $30^{\circ}C to 25^{\circ}C$, the methanol production level was enhanced by 50%. When the ratio of methane to oxygen in gas phase was increased to 2.3 from 1, produced methanol concentration was also enhanced by 100%.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.376-379
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• 2000

The methylotrophic yeast Pichia pastoris is one of the best host for the production of foreign proteins because of the presence of the strong AOX1 promoter induced by methanol. Methanol feeding induces the protein production and provides energy sources for the host cells. However, excess methanol inhibits the growth of host cells, while an insufficient methanol lead to poor growth and protein production. We have used various controled methanol feeding strategies to obtain the maximum proteins.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2145-2149
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• 2018

The formation of methanol directly from methane and steam was observed over Cu ion-exchanged mordenite. Furthermore, the continuous production of methanol was achieved by co-feeding methane and steam over Cumordenite. The methanol production rate was comparable to that reported in the stepwise process in which activation, methane reaction, and extraction of methanol were carried out separately.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.273-278
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• 1991

Methanol assimilating bacterium, Pseudomonas sp. ILS-003 was used to investigate the optimum conditions for the production of $poly-{\beta}-hydroxybutyric$ acid from methanol. For PHB production, the optimum initial pH was 6.4 and the optimum temperature was $30^{\circ}C$. Also the optimum methanol concentration was found to be 1.0%(v/v). In the PHB production, $(NH_4)_2SO_4$ was the most effective nitrogen source and the optimum concentration was 0.8 g/l, which was eqivalent to 17.4 in C/N ratio. Also, deficiency of the 2 valence metal ions in the medium had stimulating effect on PHB accumulation. Under the optimum substrate concentration, successive feeding of 0.25%(v/v) methanol was the most effective on PHB production. Under the optimum conditions, 1.94 g/l of PHB and 2.78 g/l of dry biomass were produced in 96 hours, and the yield was 69.8%(w/w).

• KSBB Journal
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• v.6 no.1
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• pp.35-43
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• 1991

The production of poly-$\beta$-hydroxybutyrate(PHB) from methanol by batch and fed-batch cultivations of Methylobacterium sp. GL-10 was studied. PHB accumulation was stimulated by the nutrients deficiency including, NH4+, SO42-, and K+. The nitrogen deficiency was the most critical factor for PHB accumulation. In batch cultivation, the maximum cell concentration and PHB content were 1.86g/l and 0.62g/l, respectively, with 1.0%(v/v) of methanol and 0.5g/1 of ammonium sulfate. The mass doubling time of Methylobacterum sp. GL-10 was in the range of 4-5 hrs. The cell growth and PHB accumulation were severely inhibited at the methanol concentration over than 2% (v/v). To overcome methanol Inhibition, constant feeding and intermittent feedillg fed-batch cultivations were adopted, using C/N molar ratio as a control factor. In constant feeding fed-batch process, cell concentration was increased up to 2.67g/1, and PHB yield was enhanced from 0.33 of batch culture to 0.53. The relatively low cell concentration was caused by methanol accumulated in culture broth at late growth phase. To prevent methanol accumulation and to maximize PHB production, DO-state intermittent fed-batch cultivation was attempted. The cell and PHB concentration was reached up to 4.55g/1 and 1.80g/1, respectively. It was possible to maintain methanol concentration low and also to feed nutrient of desired C/N molar ratio.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2098-2105
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• 2016

Massive reserves of methane ($CH_4$) remain unexplored as a feedstock for the production of liquid fuels and chemicals, mainly because of the lack of economically suitable and sustainable strategies for selective oxidation of $CH_4$ to methanol. The present study demonstrates the bioconversion of $CH_4$ to methanol mediated by Type I methanotrophs, such as Methylomicrobium album and Methylomicrobium alcaliphilum. Furthermore, immobilization of a Type II methanotroph, Methylosinus sporium, was carried out using different encapsulation methods, employing sodium-alginate (Na-alginate) and silica gel. The encapsulated cells demonstrated higher stability for methanol production. The optimal pH, temperature, and agitation rate were determined to be pH 7.0, $30^{\circ}C$, and 175 rpm, respectively, using inoculum (1.5 mg of dry cell mass/ml) and 20% of $CH_4$ as a feed. Under these conditions, maximum methanol production (3.43 and 3.73 mM) by the encapsulated cells was recorded. Even after six cycles of reuse, the Na-alginate and silica gel encapsulated cells retained 61.8% and 51.6% of their initial efficiency for methanol production, respectively, in comparison with the efficiency of 11.5% observed in the case of free cells. These results suggest that encapsulation of methanotrophs is a promising approach to improve the stability of methanol production.

• The Korea Journal of Herbology
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• v.25 no.3
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• pp.19-25
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• 2010

Objective : The aim of this study was to investigate anti-inflammatory activity of SD-01 methanol extract in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Methods : Cytotoxic activity of SD-01 methanol extract on RAW 264.7 cells was measured using 5-(3-caroboxymeth-oxyphenyl)-2H-tetra-zolium inner salt (MTS) assay. The nitric oxide (NO) production was measured by Griess reagent system. And proinflammatory cytokines and $PGE_2$ were measured by ELISA method. The levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), $I{\kappa}$-B-alpha and nuclear NF-${\kappa}$ B p65 expression were detected by western blot. Results : Our results indicated that methanol extract of SD-01 significantly inhibited the LPS-induced NO, $PGE_2$ production and iNOS, COX-2 expression accompanied by an attenuation of TNF-$\alpha$, IL-$1\beta$, IL-6 and MCP-1 production in RAW 264.7 cells. Moreover, methanol extract of SD-01 treatment also blocked LPS-induced NF-kB activation. Conclusion : These findings indicate that methanol extract of SD-01 inhibits the production of pro-inflammatory mediators and cytokines via suppression of NF-${\kappa}$ B activation. Take together, these results indicate that methanol extract of SD-01 has the potential for use as an agent of anti-chronic inflammatory diseases.