A novel restricted facultatively methylotrophic marine strain, MP T , possessing the ribulose monophosphate pathway of C 1 -carbon compound assimilation was isolated from a seawater sample obtained from Mokpo, South Korea. The novel isolate is aerobic, Gram-negative, asporogenous and a non-motile short rod. It grows well on methanol, methylated amines, dimethylsulfide and DMSO. Optimal growth occurs with 3 % NaCl at 30 6C and pH 7.0. Fructose is utilized as a multicarbon source. Growth factors are not required and vitamin B 12 does not stimulate growth. The cellular fatty acid profile of the novel strain consists primarily of straight-chain saturated C 16 : 0 and unsaturated C 16 : 1 acids. The major ubiquinone is Q-8. The dominant phospholipids are phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content is 44.9 mol% (T m ). Based on 16S rRNA gene sequence analysis and DNA-DNA relatedness (25-41 %) with the type strains of marine methylotrophs belonging to the genus Methylophaga, it is suggested that isolate MP T represents a novel species, Methylophaga aminisulfidivorans sp. nov. (type strain MP T 5KCTC 12909 T 5VKM B-2441 T 5JCM 14647 T ).Bacteria belonging to the genus Methylophaga are a unique group of aerobic, halophilic, non-methane-utilizing methylotrophs. These organisms have been isolated from various marine sediments and soda lakes. They use the ribulose monophosphate (RuMP) pathway of C 1 -carbon compound assimilation and some grow on a single multicarbon compound, fructose. Three neutrophilic species, Methylophaga marina, Methylophaga thalassica and Methylophaga sulfidovorans, have been described (Janvier et al., 1985;De Zwart et al., 1996). More recently, Methylophaga alcalica and 'Methylophaga natronica' -moderately haloalcalophilic obligately and restricted facultatively methylotrophic bacteria were described by Doronina et al. (2003a, b). Species of the genus Methylophaga are distinguished from methylobacteria of the other RuMP pathway by their requirement for Na + , Mg 2+ and vitamin B 12 , tolerance of NaCl and the low G+C content (38.0-49.0 mol%) of their DNA. On the other hand, two strains, Methylophaga marina KM3 and KM5, isolated recently from Red Sea algae were not found to require vitamin B 12 (Li et al., 2007).Here, we report the taxonomic characterization of a neutrophilic, moderately halophilic, vitamin B 12 -independent, RuMP pathway restricted facultative methylotroph belonging to the genus Methylophaga. The name Methylophaga aminisulfidivorans sp. nov. is proposed for this new isolate.The novel strain was isolated from a seawater sample collected from Mokpo, South Korea. A 1 ml sample was used to inoculate a 500 ml flask containing 50 ml mineral salts medium [MSM; 2 g KH 2 PO 4 l 21 ; 2 g (NH 4 ) 2 SO 4 l 21 ; 0.2 g MgSO 4 . 7H 2 O l 21 ; 30 g NaCl l 21 ; 0.002 g FeSO 4 . 7H 2 O l 21 ; pH 7.0] supplemented with 1 % methanol (v/v) and the flask was then incubated at 150 r.p.m. for 2 days at 30 u C. An aliquot of 0.5 ml of the turbid suspension was then transferred to ...

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Methylosinus trichosporium OB3b oxidized methane to methanol in the presence of a high concentration of Cu2+. Further oxidation of methanol to formaldehyde was prevented by adding 200 mM NaCl which acted as a methanol dehydrogenase H inhibitor. The bacterium, 0.6 mg dry cell ml(-1), in methane/air (1:4, v/v) at 25 degrees C in 12.9 mM phosphate buffer (pH 7) containing 20 mM sodium formate and 200 mM NaCl accumulated 7.7 mM methanol over 36 h.

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