Extended genetic analysis of Brazilian isolates of Bacillus cereus and Bacillus thuringiensis

Abstract

Multiple locus sequence typing (MLST) was undertaken to extend the genetic characterization of 29 isolates of Bacillus cereus and Bacillus thuringiensis previously characterized in terms of presence/absence of sequences encoding virulence factors and via variable number tandem repeat (VNTR). Additional analysis involved polymerase chain reaction for the presence of sequences (be, cytK, inA, pag, lef, cya and cap), encoding putative virulence factors, not investigated in the earlier study. MLST analysis ascribed novel and unique sequence types to each of the isolates. A phylogenetic tree was constructed from a single sequence of 2,838 bp of concatenated loci sequences. The strains were not monophyletic by analysis of any specific housekeeping gene or virulence characteristic. No clear association in relation to source of isolation or to genotypic profile based on the presence or absence of putative virulence genes could be identified. Comparison of VNTR profiling with MLST data suggested a correlation between these two methods of genetic analysis. In common with the majority of previous studies, MLST was unable to provide clarification of the basis for pathogenicity among members of the B. cereus complex. Nevertheless, our application of MLST served to reinforce the notion that B. cereus and B. thuringiensis should be considered as the same species.

Phylogenetics and antibacterial properties of exopolysaccharides from marine bacteria isolated from Mauritius seawater

“…This applies particularly for species such as Bacillus cereus and its close relatives whereby classification is difficult given that high similarity was obvious even when whole genomes were compared (Schmidt et al 2011;Okinaka and Keim 2016). This led to the suggestion that they could be genetically classified as the same organism (Zahner et al 2013). However, even though DNA-DNA hybridisation values less than the 70% threshold indicated that they were indeed distinct organisms (Guinebretière et al 2013), the species of this subclade are often referred to as the Bacillus cereus group (Ceuppens et al 2013;Zahner et al 2013) but to avoid nomenclatural confusion, we label our isolate as an unidentified Bacillus species.…”

“…This led to the suggestion that they could be genetically classified as the same organism (Zahner et al 2013). However, even though DNA-DNA hybridisation values less than the 70% threshold indicated that they were indeed distinct organisms (Guinebretière et al 2013), the species of this subclade are often referred to as the Bacillus cereus group (Ceuppens et al 2013;Zahner et al 2013) but to avoid nomenclatural confusion, we label our isolate as an unidentified Bacillus species.…”

Biofilm mediated synergistic degradation of hexadecane by a naturally formed community comprising Aspergillus flavus complex and Bacillus cereus group

“…BLAST analysis of the nucleotide sequence of 16 s rRNA gene of the bacterium showed the maximum identity with B. cereus group bacteria, B. cereus , B. thuringiensis and B. anthracis , revealing that it is difficult to differentiate between them [28–31]. B. anthracis is non-motile.…”

Typing and evaluating heat resistance of Bacillus cereus sensu stricto isolated from the processing environment of powdered infant formula

“…Seven housekeeping genes, glpF (glycerol uptake facilitator protein), gmk (putative guanylate kinase), ilvD (dihydroxy-acid dehydratase), pta (phosphate acetyltransferase), pur (phosphoribosylamino-imidazolecarboxamide), pycA (pyruvate carboxylase), and tpi (triosephosphate isomerase), were chosen according to the B. cereus MLST database (http: / / pubmlst .org/ bcereus/ ). These 7 housekeeping genes are used to classify the B. cereus group because they are single copy, have high discriminatory power, and are not subject to lateral transfer or genetic recombination (Priest et al, 2004;Zahner et al, 2013;Liu et al, 2017). The PCR products were sequenced by SinoGenoMax Co. Ltd.…”