Characterization and Methanol Biosynthesis of a Methane-Oxidizing Bacterium, Methylomonas sp. SM4, Isolated from Rice Paddy Field Soil
2017
Park, S.M., Chosun University, Gwangju, Republic of Korea | Lavanya Madhavaraj, Chosun University, Gwangju, Republic of Korea | Kim, S.W., Chosun University, Gwangju, Republic of Korea
A methane-oxidizing bacterium was isolated from rice paddy field soil around Jeollanam-do province, Korea, and characterized. The isolate was gram-negative, orange pigmented and short rod (1.1-1.2 x 1.6-1.9 micrometer). It was catalase and urease-negative but oxidase-positive. The strain utilized methane and methanol as sole carbon and energy sources. It had an ability to grow with an optimum pH 7.0 and an optimum growth temperature 30oC. The strain was resistant to antibiotic polymyxin B but sensitive to streptomycin, kanamycin, ampicillin, chloramphenicol and rifampicin. The isolate required copper for their growth with concentration range of 2-25 μM, with an optimum of 10 μM. Under optimal culture condition, specific cell growth rate and generation time were found to be 0.046 hr-1 and 15.13 hr, respectively. Phylogenetic analysis based on 16S rDNA sequences indicated that the strain formed a tight phylogenetic lineage with Methylomonas koyamae with a value of 99.4% gene sequence homology. So, we named the isolate as Methylomonas sp. SM4. 8.6 mM methanol was accumulated in the reaction mixture containing 70 mM sodium formate and 40 mM MgCl2 (MDH inhibitor) under atmosphere of methane:air (40:60) mixture for 24 hr at 30℃.
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