Methylocystis iwaonis sp. nov., a type II methane-oxidizing bacterium from surface soil of a rice paddy field in Japan, and emended description of the genus Methylocystis (ex Whittenbury et al. 1970) Bowman et al. 1993

Abstract

A novel methane-oxidizing bacterial strain SS37A-ReT was isolated from surface soil of a rice paddy field in Japan. Cells were Gram-stain-negative, motile rods with single polar flagellum and type II intracytoplasmic membrane arrangement. The strain grew on methane or methanol as the sole carbon and energy source. It grew at 15–37 °C (optimum 25–30 °C), pH 6.0–9.0 (optimum 7.0–8.0) and with 0–0.1 % (w/w) NaCl (no growth at 0.5 % or above). Cells formed cysts, but not exospores. The results of sequence analysis of the 16S rRNA gene indicated that SS37A-ReT represented a member of the family Methylocystaceae , with the highest similarity (98.9 %) to Methylocystis parva corrig. OBBPT. Phylogenetic analysis of pmoA and mxaF genes and core genes in the genome indicated that the strain was closely related to the members of the genus Methylocystis , while the analysis of the mmoX gene indicated the close relationships with the genus Methylosinus . The values of genome relatedness between SS37A-ReT and species of the genera Methylocystis and Methylosinus were 78.6–82.5% and 21.7–24.9 % estimated by the average nucleotide identity and digital DNA–DNA hybridisation, respectively, showing the highest values with Methylocystis echinoides LMG 27198T. The DNA G+C content was 63.2 mol% (genome). The major quinone and fatty acids were Q-8 and, C18 : 1 (C18 : 1ω8t and C18 : 1ω8c) and C18 : 2, respectively. On the basis of the phenotypic and phylogenetic features, the strain represents a novel species of the genus Methylocystis , for which the name Methylocystis iwaonis sp. nov. is proposed. The type strain is SS37A-ReT (=JCM 34278T =NBRC 114996T=KCTC 82710T).

Methylocystis suflitae sp. nov., a novel type II methanotrophic bacterium isolated from landfill cover soil

“…Fatty acid analysis indicates that strain NLS-7 T contains C 18:1 ω8c, C 18:1 ω7c as predominant fatty acids. C 18:1 ω8c is present in all classified members of the genus Methylocystis and C 18:1 ω7c is present in all species of Methylocystis except for M. iwaonis [12] as shown in Table 2. For strain NLS-7 T , C 18:1 ω8c and C 18:1 ω7c are present at the highest abundance at over 97 % of the entire fatty acid profile with all other fatty acids present only at trace amounts.…”

“…Although we did not grow all nine of the species in parallel, we used very similar growth conditions to grow our cells as were used for the other data. Specifically the data from the characterization of M. iwaonis which grew cells for fatty acid analysis in NMS medium at 30 °C [12].…”

“…Since then, six more isolates have been characterized within the genus. These include: M. rosea [7], M. hirsuta [8], M. heyeri [9], M. bryophila [10], M. silviterrae [11] and M. iwaonis [12]. The work done to characterize the M. iwaonis species presents the most recent emendation and description of the genus Methylocystis [12].…”

“…Numbers represent the relative percentage of the acid. The data for strain NLS-7 T were obtained in this study with the rest of the data obtained in the work describing the characterization of M. iwanois[12]. Trace fatty acids comprising <1 % of the total profile are not presented and shown as a dash…”