Emended descriptions of Geobacillus thermoleovorans and Geobacillus thermocatenulatus

Abstract

Nineteen thermophilic, aerobic, endospore-forming bacterial strains were subjected to 16S rRNA gene sequence analysis. Eight of these strains had been received as cultures of Geobacillus kaustophilus, G. lituanicus, G. stearothermophilus, ‘G. thermoleovorans subsp. stromboliensis’, G. vulcani, ‘Bacillus caldolyticus’, ‘B. caldotenax’ and ‘B. caldovelox’, but they showed close relationships with the type strain of G. thermoleovorans, as did two other strains received as G. thermoleovorans. All strains underwent further taxonomic analysis by API and other phenotypic tests and fatty acid methyl ester analysis, and selected strains were analysed for their polar lipids and for DNA relatedness. The 11 strains that formed the G. thermoleovorans 16S rRNA cluster also showed some phenotypic similarities, and DNA relatedness data support the reassignment of the strains received as G. kaustophilus, G. lituanicus, ‘G. thermoleovorans subsp. stromboliensis’, G. vulcani, ‘B. caldolyticus’, ‘B. caldotenax’ and ‘B. caldovelox’, and one of the G. stearothermophilus strains, as members of the species G. thermoleovorans. Four other strains received as G. kaustophilus were misnamed; two were identified as G. stearothermophilus and two appeared to be closely related to Anoxybacillus rupiensis. One strain received as G. stearothermophilus remained unidentified. On the basis of a single strain, Geobacillus thermocatenulatus was shown to represent a distinct species, but study of the type strain of Geobacillus gargensis showed this species to be a later heterotypic synonym of Geobacillus thermocatenulatus. Emended descriptions of Geobacillus thermoleovorans and Geobacillus thermocatenulatus are therefore presented.

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

“…DNA extraction and 16S rRNA gene sequencing was carried out as described by Coorevits et al (2011). All sequences were aligned using the integrated aligner of ARB (Ludwig et al, 2004) and manual refinement.…”

“…Reliability of clusters was assessed by calculating bootstrap values based on 1000 replications. DNA-DNA hybridization experiments and determination of DNA G+C content were performed as described by Dinsdale et al (2011).…”

“…For fatty acid methyl ester analysis, the method of Vauterin et al (1991) was followed, including standardization of incubation temperature (52 uC), incubation time (24 h) and physiological age (overlap area of the second and third quadrant from a quadrant streak); profiles were identified and clustered using the Microbial Identification System software and MIDI TSBA database version 5.0. Polar lipids were extracted and separated as described by Dinsdale et al (2011) after growth on TSA (Oxoid) at 52 uC for 24 h.…”

“…nov. is proposed. Dinsdale et al (2011) reported that strains R-32636 and R-32637, isolated from near Lake Taupo, New Zealand and received as Geobacillus kaustophilus, most probably belonged to Anoxybacillus rupiensis. DNA relatedness values confirmed this (Table 3), and phenotypic data for these two strains for characters that were not included in the original description of this species are given in Table S2.…”

Characterization and evaluation of tandem repeats for the identification of Geobacillus

“…Taxonomy of thermophilic, endospore-forming bacteria has evoked a great interest over the past few years [1][2][3][4][5]. Thermophilic endospore-formers constitute an excellent resource of biotechnologically important products and can be used as the producers of these proteins [6][7][8][9][10].…”