• Korean Journal of Microbiology
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• v.28 no.4
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• pp.290-296
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• 1990

Putrescine, spermidine, and spermine were found to persent in Methylobacterium extorquens AM1 growing on methanol, succinate, glucose, or nutrient broth as an energy source. Spermidine was found to be a major polyamine in cells growing on methanol or succinate, while putrescine to be the one in nutrient broth-grown cells. The overall content of polyamines in cells growing on glucose was less than that in cells growing on other substrates. Spermine was the most abundant polyamine in glucose-grown cells. Accumulation of polyamines in M. extorquens AM1 was maximal at the mid-exponential or early stationary phase during growth on each substrate. The effect of polyamines added into the medium on the polyamine composition in M. extorquens AM1 was variable. Each polyamine added into the nutrient broth medium was found to increase the amount of the respective polyamine in the cell. Exogeneously added polyamines had no effect on the growth of M. extorquens AM1.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.363-368
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• 2017

Methylotrophy is able to use reduced one-carbon compound, such as methanol and methylamine, as a sole carbon source. Methylobacterium extorquens AM1 is the most extensively studied methylotroph utilizing serine-isocitrate lyase cycle. Because the Poly 3-hydroxybutyrate (PHB) synthesis pathway in M. extorquens AM1 is likely to interlink with EMCP (ethylmalonyl-CoA pathway), glyoxylate, and TCA cycles, regulation of PHB production is needed to produce EMCP-derived acid or TCA acids. To adjust carbon flux to PHB production, PhaR, which seems to have function of regulator of PHB synthesis and acetyl-CoA flux, was knocked out in M. extorquens AM1 by using markerless gene deletion methods. As a result, PHB granules were remarkably reduced in the knockout strain ${\Delta}phaR$ compared to parental strain. Although lag phase was extended for 12h, ${\Delta}phaR$ showed similar cell growth and methanol consumption rate compared to wild type.

• Korean Journal of Microbiology
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• v.29 no.6
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• pp.387-391
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• 1991

Methylobacterium extorquens AM1 growing on methanol as a sole source of carbon and energy was found to grow most rapidly (t$t_{d}$ =6h) at 30.deg.C in a mineral medium (pH 7.0) containing 0.5% (v/v) methanol which was agitated at 200 rpm (optimal cultivation condition). Cells grown under the optimal cultivation condition contained more spermidine, but less putrescine, than the cells grown on 2.5%(v/v) ( $t_{d}$ =8h ) or at 20.deg.C ( $t_{d}$ =8h ). Cells cultivated under the optimal condition was found to contain more spermidine than the cells grown at pH 6.0 (( $t_{d}$ =7h ) and pH 8.0 ($t_{d}$ =7.3h). the cells growing at the stationary phase under the optimal condition accumulated more spermine or putrescine than the cells growing at the same phase on 2.5%(v/v) methanol or at pH 6.0 and pH 8.0, respectively. M. extorquens AM1 grown in a medium agitated at 100 rpm ( $t_{d}$ =8.8h ) contained less spermidine and spermine than the cells grown under the optimal cultivation condition.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.1
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• pp.46-53
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• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf, stem, grain, root and rhizosphere soil sainples of four rice cultivars collected from three regions of Korea. Thirty five pigmented and five non-pigmented isolates showing characteristic growth on methanul were obtained. When phylotypes were defined by performing numerical analysis of 42 characteristics, four distinct clusters were formed. While two clusters, I and IV diverged on the basis of nitrate and nitrite reduction, other two clusters, comprising only pink pigmented colonies, diverged on the basis of cellulase activity. Out of the two reference strains used in the analysis, Methyhbacterium extorquens AM1 diverged from all the clusters and M. fujisawaense KACC 10744 grouped under cluster III. All the isolates were positive for urease, oxidase, catalase and pectinase activity and negative for indole production, MR and VP test, $H_2S$ production, starch, and casein hydrolysis. No clusters were found to possess thermotolerant isolates, as no growth of the isolates was observed at $45^{\circ}C$. Two strains in cluster I were found to possess gelatin hydrolysis and methane utilizing properties respectively. Most of the isolates in all the four clusters utilized monosaccliarides, disaccharide and polyols as carbon source. Six isolates showed considerable nitrogenase activity ranging from 86.2 to $809.9nmol\;C_2H_4\;h^{-1}\;mg^{-1}$ protein.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.235-244
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• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf samples of 19 rice cultivars collected from three regions of Korea. Nineteen pink pigmented isolates showing characteristic growth on methanol were obtained. Physiological and biochemical characters of each isolate were examined according to methods described in Bergey's Manual of Systematic Bacteriology. When phylotypes were defined by performing numerical analysis of 37 characteristics, four distinct clusters were formed. The two reference strains, Methylobacterium extorquens AM1 and Methylobacterium fujisawaense KACC10744 were found to group under cluster IV and cluster III respectively. Cluster I diverged on the basis of nitrate reduction and four isolates showed tolerance upto 0.5 M NaCl concentrations. Two strains in cluster I and III were found to possess methane utilizing properties. Most of the isolates in all the four clusters utilized monosaccharides, disaccharide and polyols as carbon source. When the isolates were subjected for indole-3-acetic acid (IAA) analysis in the presence of L-tryptophan, only 8 isolates exhibited IAA production. In addition, the nitrogen source in the medium was found to influence the IAA production. Addition of $(NH_4)_2SO_4$ in the medium led to a 2 to 30 fold increase in the indole synthesis. However, $KNO_3$, $NH_4NO_3$ and $NH_4Cl$ substitution did not significantly stimulate the synthesis of IAA in the growth medium. Result of gnotobiotic root elongation assay significantly increased roots and shoots lengths, and number of lateral roots, which is mediated by IAA production in the culture medium. The rice seedlings primary roots from seeds treated with methylotrophic isolates were on average 27 to 56% longer than the roots from seeds treated with the uninoculated seeds. In addition, application of different high concentrations of authentic IAA ($400g\;mL^{-1}$) to roots of rice seedlings inhibited root growth. However, the IAA concentration from 10 to $200g\;mL^{-1}$, IAA promoted root growth of rice seedlings. These results suggest that bacterial IAA plays a major role in the development of the host plant root system.