Bacillus weihenstephanensischaracteristics are present inBacillus cereusandBacillus mycoidesstrains

Abstract

The Bacillus cereus group comprises seven bacterial species: Bacillus cereus, Bacillus anthracis, Bacillus thuringiensis, Bacillus mycoides, Bacillus pseudomycoides, Bacillus cytotoxicus, and Bacillus weihenstephanensis. Bacillus weihenstephanensis is distinguished based on its capability to grow at 7 °C but not at 43 °C, and the presence of specific signature sequences in the 16S rRNA and cspA genes and in several housekeeping genes: glpF, gmK, purH, and tpi. Bacillus weihenstephanensis-specific signature sequences were found in some B. cereus and B. mycoides strains suggesting psychrotolerance. This was confirmed by growth at 7 °C but not at 43 °C. The other B. cereus and B. mycoides strains and all B. anthracis, B. thuringiensis, and B. pseudomycoides harbored the mesophilic signature sequences. The strains tested grew at 43 °C but did not grow at 7 °C. A maximum-likelihood phylogenetic tree was inferred from comparisons of the concatenated nucleotide sequences. Three groups and one branch were revealed. Group I, II, and III comprised the mesophilic B. cereus, some mesophilic B. mycoides, and all B. anthracis and B. thuringiensis strains; the psychrotolerant B. cereus and B. mycoides, and all B. weihenstephanensis strains; and some mesophilic B. mycoides and all B. pseudomycoides strains, respectively. The branch corresponds to the single B. cytotoxicus strain. Based on psychrotolerance and multilocus sequence analysis, further confirmed by comparisons of amino acid sequences, we show that some B. cereus and B. mycoides strains should be reclassified as B. weihenstephanensis.

Switching of the rotational direction of rhizoidal colonies in a newly isolated <i>Bacillus mycoides</i> strain Ko01

“…1). We further analyzed the small region of cspA, glpF, gmk, purH, and tpi genes with a known SNP that are unique to each subgroup of B. cereus group strains (Lechner et al, 1998;Soufiane and Cote, 2013). All of the SNP sequences of Ko01 were identical to the consensus sequences of the group II strains (Table 2), supporting our notion that the Ko01 strain belongs to the group II B. cereus group.…”

“…Among seven rhizoidal colony forming strains, five distinctive patterns of how colony rotation changes in response to the variations in agar concentration were observed (Table 3). So far, the classification of B. mycoides has been mainly restricted to sequence-based phylogeny and growth temperature studies (Lechner et al, 1998;Soufiane and Cote, 2013). We propose that colony chirality patterns can be used as an additional tool to distinguish B. mycoides strains.…”

“…Phylogenetically, they belong to the Bacillus cereus group, comprising B. mycoides, B. cereus, B. thuringiensis, B. pseudomycoides, B. weihenstephanensis, B. anthracis, and B. cytotoxicus (Soufiane and Cote, 2013). B. cereus group is further classified into subgroups I, II and III.…”

“…By contrast, strains belonging to group I and III are mesophilic. Signature sequences of housekeeping genes such as 16S rRNA, cspA and glpF can also be used to differentiate these subgroups (Pruss et al, 1999;Soufiane and Cote, 2013).…”

“…Despite B. mycoides strains sharing a common phenotypic trait of forming rhizoidal colonies, B. mycoides strains are not clustered into a single phylogenetic lineage (Soufiane and Cote, 2013). For example, B. mycoides strains BGSC 6A14, BGSC 6A68, and BGSC 6A19, are classified into subgroups I, II and III of B. cereus group, respectively.…”