Reclassification of Saccharococcus caldoxylosilyticus as Geobacillus caldoxylosilyticus (Ahmad et al. 2000) comb. nov.

Abstract

A polyphasic study was performed on five thermophilic strains belonging to the genus Bacillus, isolated from soil of different geographical areas. 16S rRNA gene sequence analysis placed these isolates in RNA group 5, with Saccharococcus caldoxylosilyticus and [Bacillus] thermoglucosidasius being the closest phylogenetic neighbours. The type species of Saccharococcus, Saccharococcus thermophilus, was only moderately related to these two species and the novel isolates. DNA-DNA hybridization studies and comparison of morphological, chemotaxonomic and phenotypic features supported the close relationship between the novel isolates and Saccharococcus caldoxylosilyticus. These data justify the reclassification of Saccharococcus caldoxylosilyticus. Following the transfer of the validly described Bacillus species of group 5 into the genus Geobacillus, the reclassification of Saccharococcus caldoxylosilyticus as Geobacillus caldoxylosilyticus comb. nov. is proposed. This species can be distinguished genomically from Geobacillus thermoglucosidasius, Geobacillus stearothermophilus, Geobacillus thermodenitrificans and Saccharococcus thermophilus by a specific PCR-RFLP assay targeting the 16S rDNA.

The Geobacillus paradox: why is a thermophilic bacterial genus so prevalent on a mesophilic planet?

“…Strain descriptions of novel Geobacillus species rarely report spore size. But it is apparent, from both my unpublished observations and others' published micrographs, that most Geobacillus spores are slightly ovoid, with an average diameter close to the size required to fit into the scavenging gap (Fortina et al, 2001;Nazina et al, 2001). Further, Bacillus and Geobacillus endospores are notorious for their extreme resistance to UV light, temperature changes and desiccation (Driks, 2002;Nicholson et al, 2000;Setlow, 2006;Takamatsu & Watabe, 2002), the very environmental challenges faced by airborne bacteria (Griffin, 2007).…”

Taxonomic revision of the genus Geobacillus : emendation of Geobacillus , G. stearothermophilus , G. jurassicus , G. toebii , G. thermodenitrificans

“…Saccharococcus caldoxylosilyticus was described by Ahmad et al (2000) and transferred to Geobacillus by Fortina et al (2001). The type strain R-35639 T was the only strain available and had no near neighbours in the phenotypic analysis (Fig.…”

“…Nazina et al (2001) proposed that the six species of that lineage, namely B. stearothermophilus, B. kaustophilus, B. thermoglucosidasius, B. thermocatenulatus, B. thermoleovorans and B. thermodenitrificans, should be accommodated in a new genus, Geobacillus, along with two novel species, Geobacillus subterraneus and Geobacillus uzenensis. Subsequently, Bacillus pallidus (Scholz et al, 1987), Saccharococcus caldoxylosilyticus (Ahmad et al, 2000) and Bacillus vulcani (Caccamo et al, 2000) were transferred to Geobacillus (Fortina et al, 2001;Banat et al, 2004;Nazina et al, 2004) and then Miñana-Galbis et al (2010) proposed the further transfer of Geobacillus pallidus to the new genus Aeribacillus. Subsequently, six further species, Geobacillus toebii (Sung et al, 2002), G. gargensis (Nazina et al, 2004), G. debilis , G. lituanicus (Kuisiene et al, 2004), G. tepidamans (Schäffer et al, 2004) and G. jurassicus (Nazina et al, 2005) have been proposed and the names 'Geobacillus caldoproteolyticus' (Chen et al, 2004) and the subspecies 'G.…”

Planifilum fimeticola gen. nov., sp. nov. and Planifilum fulgidum sp. nov., novel members of the family ‘Thermoactinomycetaceae’ isolated from compost

“…Utilization of sugars was tested using the methods of Shirling & Gottlieb (1966) and Fortina et al (2001). No reproducible results were obtained because of the weak growth of the strains (data not shown).…”