Polyphasic characterization of Bacillus coagulans strains, illustrating heterogeneity within this species, and emended description of the species

Abstract

Because of its food spoiling capacity on the one hand and its significant role in the production of industrially valuable products on the other, Bacillus coagulans is of economic concern. Several studies have revealed a great deal of diversity within the species and this has led to a number of taxonomic adjustments. The present study aims to clarify the diversity within Bacillus coagulans sensu stricto and determine the taxonomic status of the species. Therefore, a polyphasic study was performed on a set of B. coagulans strains from diverse habitats. Techniques as ARDRA, SDS-PAGE of whole cell proteins, FAME analysis, routine phenotypic tests and rep-PCR illustrate considerable intra-species heterogeneity, while 16S rDNA sequence comparison and DNA-DNA relatedness support the accommodation of these strains in one species. Although most techniques demonstrate appreciable heterogeneity among the Bacillus coagulans strains, the intraspecies groupings are not consistent throughout all the methods applied and are not supported by any economic, historic or practical traits. Therefore, a division in subspecies seems inappropriate. In attempt to achieve a better species delineation, an emended description of Bacillus coagulans is included.