Temperature Dependence of the Proteome Profile of the Psychrotolerant Pathogenic Food Spoiler Bacillus weihenstephanensis Type Strain WSBC 10204

Abstract

Bacillus weihenstephanensis is a subspecies of the Bacillus cereus sensu lato group of spore-forming bacteria known to cause food spoilage or food poisoning. The key distinguishing phenotype of B. weihenstephanensis is its ability to grow below 7 °C or, from a food safety perspective, to grow and potentially produce toxins in a refrigerated environment. Comparison of the proteome profile of B. weihenstephanensis upon its exposure to different culturing conditions can reveal clues to the mechanistic basis of its psychrotolerant phenotype as well as elucidate relevant aspects of its toxigenic profile. To this end, the genome of the type strain B. weihenstephanensis WSBC 10204 was sequenced and annotated. Subsequently, the proteome profiles of cells grown at either 6 or 30 °C were compared, which revealed considerable differences and indicated several hundred (uncharacterized) proteins as being subproteome- and/or temperature-specific. In this manner, several processes were newly indicated to be dependent on growth temperature, such as varying carbon flux routes and a different role for the urea cycle. Furthermore, a possible post-translational regulatory function for acetylation was suggested. Toxin production was determined to be largely independent of growth temperature.

Bacillus cereus Group-Type Strain-Specific Diagnostic Peptides

“…We may have lost candidate diagnostic peptides because we did not grow the cultures at low temperatures and thus did not exploit a temperature-specific protein expression profile of this psychrotolerant species. 25 Instead, we chose comparable culturing conditions for all type strains to facilitate the development of a simple assay to differentiate isolates from the B. cereus group. It is worth mentioning that cells which have transformed from the vegetative to the sporulative state would introduce additional signals into the mass spectral protein and peptide profiles.…”

“…The categories cell envelope, cellular processes, energy metabolism, unclassified, and unknown function are covered by at least four of the seven type strains investigated. The variation of the number of verified diagnostic peptides per type strain may be explained by (I) the very high genetic relatedness of distinct B. cereus group strains combined with their different genome sizes; for example, B. cytotoxicus comprises ∼3840 proteins, which is ∼ 1 / 4 less than the other type strains, (II) the number of sequenced genomes available per B. cereus species, (III) not exploiting specific phenotypic characteristics during strain cultivation, that is, psychrotolerance ( B. weihenstephanensis ), rhizoidal growth ( B. mycoides and B. pseudomycoides ), thermotolerance ( B. cytotoxicus ), which could result in a differential protein expression profile, and (IV) probable incorrect affiliation of individual strains deposited on UniProt. Rarely, more than one diagnostic peptide is found within the same protein.…”

“…Only one diagnostic peptide was identified for B. weihenstephanensis (Table S-3). We may have lost candidate diagnostic peptides because we did not grow the cultures at low temperatures and thus did not exploit a temperature-specific protein expression profile of this psychrotolerant species . Instead, we chose comparable culturing conditions for all type strains to facilitate the development of a simple assay to differentiate isolates from the B. cereus group.…”

“…Accordingly, this microorganism has industrial application as a biological pesticide and its molecular genetics served as a basis for the bioengineering of transgenic plants and for plant-associated bacteria such as Pseudomonas fluorescens . , However, certain B. thuringiensis isolates have also been linked to human cutaneous infections , and occasionally encodes the emetic toxin cereulide. , The combination of these two characteristics may pose a problem from a food safety perspective. The remaining B. cereus group species, that is, B. mycoides , B. pseudomycoides , and B. toyonensis , are considered to be nonpathogenic organisms. ,, Bacillus mycoides and B. pseudomycoides are easily recognized by their rhizoidal colonial growth, , whereas they differ from each other in their fatty acid profiles …”

Transcriptome and Proteome of Fish-Pathogenic Streptococcus agalactiae Are Modulated by Temperature

“…All microorganisms respond to temperature variation through increased expression of heat shock or cold shock proteins, which act as activators or repressors of several other proteins (Ehira et al, 2009 ). Evaluation of the temperature-induced transcriptome using microarray technology has been reported in Yersinia pestis (Han et al, 2004 ), Escherichia coli (Gadgil et al, 2005 ), Streptococcus pyogenes (Smoot et al, 2001 ), and GBS (Mereghetti et al, 2008 ), whereas shotgun proteomics analysis has been used to evaluate differential protein abundance induced by temperature in E. coli (Kocharunchitt et al, 2012 ), Ochrobactrum anthropi (Varano et al, 2016 ), and Bacillus weihenstephanensis (Stelder et al, 2015 ).…”