|Rooney, Alejandro - Alex|
Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2009
Publication Date: 4/15/2009
Citation: Vaishampayan, P., Miyashita, M., Ohnishi, A., Satomi, M., Rooney, A.P., Duc, M.T., Venkateswaran, K. 2009. Description of Rummeliibacillus stabekisii gen. nov., sp. nov. and Reclassification of Bacillus pycnus Nakamura et al. 2002 as Rummeliibacillus pycnus comb. nov. International Journal of Systematic and Evolutionary Microbiology. 59(Pt 5):1094-1099. Interpretive Summary: This manuscript describes work on the taxonomy of bacteria species related to the genus Bacillus. A new genus, Rumeliibacillus, was discovered and is described in this paper. In addition, a previously described species, Bacillus pycnus, was found to belong to this new genus and therefore was subsequently reclassified as a species of Rumeliibacillus. These findings will facilitate current and future research efforts by scientists working to identify novel strains of Bacillus and Rumeliibacillus for various agricultural or biotechnological purposes.
Technical Abstract: Strains of aerobic, Gram-positive rods, and round spore-forming bacteria were isolated from a variety of geographic locations, and a subsequent polyphasic study was undertaken to clarify the taxonomic position of the round spore-forming isolates: strain KSC-SF6gT, strain M32, and strain NBRC 12622. Ribosomal gene (16S rRNA) sequence similarities demonstrated that these strains were most closely affiliated with Bacillus pycnus NRS-1691T (98%), with species of Kurthia (96%) and Viridibacillus (94 to 96%) as the next nearest relatives. However, while DNA-DNA hybridization studies showed about 70% reassociation among strains KSC-SF6gT, M32, and NBRC 12622, DNA-DNA hybridization values between these strains and B. pycnus NRRL NRS-1691T never exceeded 13%. Differences in the molecular structure of cell-wall peptidoglycan could not sufficiently differentiate these strains from other closely related genera (Viridibacillus and Kurthia). However, Lys–Asp was present in strains KSC-SF6gT, M32, and NBRC 12622, whereas L-Lys–D-Glu was reported in B. pycnus NRRL NRS-1691T. The menaquinone MK-7 was dominant in strains KSC-SF6gT, M32, and NBRC 12622 and members of the Kurthia genus, whereas MK-8 was abundant in Viridibacillus species. Strains KSC-SF6gT, M32, NBRC 12622 exhibited fatty acid profiles consisting of major amounts of ai-C15:0 (approximately 50%) and i-C15:0 (approximately 25%) and moderate amounts of ai-C17:0 (approximately 7%), which discriminated them from closely related B. pycnus NRRL NRS-1691T and species of Viridibacillus (i-C15:0; approximately 46 to 74%). The authors propose that strains KSC-SF6gT, M32, NBRC 12622 and B. pycnus NRRL NRS-1691T be reclassified into a separate genus, based on a) clear-cut differences in discriminative taxonomic markers, and b) the distant placement of B. pyncnus and the novel strains described herein from other species of this clade according to current 16S rRNA gene sequence-based relatedness (approximately 4% difference in sequence). We propose the placement of these isolates into the novel genus Rummeliibacillus gen. nov. For this new taxon, comprising strains KSC-SF6gT, M32, and NBRC 12622, we propose the name Rummeliibacillus stabekisii gen. nov., sp. nov. (the type species of Rummeliibacillus), represented by the type strain Rummeliibacillus stabekisii KSC-SF6gT (=NRRL B-51320T =NBRC 104870T). In addition, a B. pycnus strain bearing distinct traits from other round-spore-forming species (i.e., absence of growth at high NaCl (7%), positive reaction for gelatin liquefaction) were reclassified as Rummeliibacillus pycnus comb. nov. based on phylogenetic affiliations and phenotypic characterizations.