and LAY possessed only a soluble form of methane monooxygenase (sMMO) and lacked intracytoplasmic membranes. Growth occurred only on methane and methanol; the latter was the preferred growth substrate. mRNA transcripts of sMMO were detectable in cells when either methane or both methane and methanol were available. Carbon was assimilated via the serine and ribulose-bisphosphate (RuBP) pathways; nitrogen was fixed via an oxygen-sensitive nitrogenase. Strains AR4 T , SOP9 and LAY were moderately acidophilic, mesophilic organisms capable of growth between pH 3.5 and 7.2 (optimum pH 4.8-5.2) and at 4-33 6C (optimum 20-23 6C).The major cellular fatty acid was 18 : 1v7c and the quinone was Q-10. The DNA G+C content was 55.6-57.5 mol%. The isolates belonged to the family Beijerinckiaceae of the class Alphaproteobacteria and were most closely related to the sMMO-possessing methanotrophs of the genus Methylocella (96.4-97.0 % 16S rRNA gene sequence similarity), particulate MMO (pMMO)-possessing methanotrophs of the genus Methylocapsa (96.1-97.0 %), facultative methylotrophs of the genus Methylovirgula (96.1-96.3 %) and non-methanotrophic organotrophs of the genus Beijerinckia (96.5-97.0 %). Phenotypically, strains AR4 T , SOP9 and LAY were most similar to Methylocella species, but differed from members of this genus by cell morphology, greater tolerance of low pH, detectable activities of RuBP pathway enzymes and inability to grow on multicarbon compounds. Therefore, we propose a novel genus and species, Methyloferula stellata gen. nov., sp. nov., to accommodate strains AR4 The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences and partial mmoX gene sequences of strains AR4 T , SOP9 and LAY are FR686343-FR686345 (16S rRNA gene) and FR686346-FR686348 (mmoX), respectively, and those for the partial mxaF, nifH and rbcL sequences of strain AR4T are FR686349, FR686351 and FR686352, respectively.

Functional and genomic diversity of methylotrophic Rhodocyclaceae: description of Methyloversatilis discipulorum sp. nov.

No abstract

Eight strains of non-methane-utilizing aerobic methylotrophic bacteria able to grow on chloromethane as the carbon and energy source have been isolated. Based on their phenotypic and genomic characteristics the new isolates were classified as Hyphomicrobium spp. (strains CMl, CM2, CM9, CM29, CM35) and Methylobacterium spp. (strains CM4, CM30, CM34). All the strains possessed an inducible yet unknown enzyme that catalyzed conversion of chloromethane to HCI and formaldehyde. The latter was oxidized via formate to CO2 or assimilated through icl+ or icl-variants of the serine pathway.

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 ...