Emended descriptions of Bacillus sporothermodurans and Bacillus oleronius with the inclusion of dairy farm isolates of both species

Bacillus sporothermodurans is an industrially important micro-organism because of its ability to produce endospores which resist ultra-high temperature (UHT) and industrial sterilization processes. It was described by Pettersson et al. (1996) [Pettersson, B., Lembke, F., Hammer, P., Stackebrandt, E. & Priest, F. G. (1996). Int J Syst Bacteriol 46, 759-764] based on seven genetically homogeneous isolates all from UHT milk. Bacillus oleronius, the closest phylogenetic neighbour of B. sporothermodurans, was described by Kuhnigk et al. (1995) [Kuhnigk, T., Borst, E.-M., Breunig, A., König, H., Collins, M. D., Hutson, R. A. & Kämpfer, P. (1995). Can J Microbiol 41, 699-706] based on a single strain, isolated from the hindgut of the termite Reticulitermes santonensis. A polyphasic study of a heterogeneous collection of B. sporothermodurans and B. oleronius strains isolated from various sources and geographical origins led to an emended description of both species. Additional data presented are the results of fatty acid, quinone and/or cell wall (polar lipid) analyses. DNA-DNA hybridization confirmed 3 subgroups of strains obtained after SDS-PAGE analysis of cellular proteins as B. sporothermodurans. One named B. sporothermodurans strain (R-7489) was reclassified as a Bacillus fordii strain. The phenotypic profiles of both species were rather heterogeneous, sometimes different from the original descriptions and did not differ in a large number of characteristics, although B. oleronius generally gave stronger reactions in its positive tests than did B. sporothermodurans; the variable and weak reactions for both organisms with some substrates blurred the distinction between the two. However, differences in polar lipid, SDS-PAGE and menaquinone profiles clearly allow distinction between the two species.