Für Studenten
Diagnostik und Industrieberatung
FTIR Spektrenbibliotheken

Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL)

Abteilung Mikrobiologie
Technische Universität München
Weihenstephaner Berg 3
D-85350 Freising

BMC Evol Biol. 2015 Nov 10;15:246. doi: 10.1186/s12862-015-0529-4.

Massive horizontal gene transfer, strictly vertical inheritance and ancient duplications differentially shape the evolution of Bacillus cereus enterotoxin operons hbl, cytK and nhe.

Böhm ME1, Huptas C2, Krey VM3,4, Scherer S5.



Bacillus cereus sensu lato comprises eight closely related species including the human pathogens Bacillus anthracis and Bacillus cereus. Within B. cereus sensu lato, chromosomally and plasmid-encoded toxins exist. While plasmid-mediated horizontal gene transfer of the emetic toxin, anthrax and insecticidal toxins is known, evolution of enterotoxin genes within the group has not been studied.


We report draft genome assemblies of 25 strains, a phylogenetic network of 142 strains based on ANI derived from genome sequences and a phylogeny based on whole-genome SNP analysis. The data clearly support subdivision of B. cereus sensu lato into seven phylogenetic groups. While group I, V and VII represent B. pseudomycoides, B. toyonensis and B. cytotoxicus, which are distinguishable at species level (ANI border ≥ 96 %), strains ascribed to the other five species do not match phylogenic groups. The chromosomal enterotoxin operons nheABC and hblCDAB are abundant within B. cereus both isolated from infections and from the environment. While the duplicated hbl variant hbl a is present in 22 % of all strains investigated, duplication of nheABC is extremely rare (0.02 %) and appears to be phylogenetically unstable. Distribution of toxin genes was matched to a master tree based on seven concatenated housekeeping genes, which depicts species relationships in B. cereus sensu lato as accurately as whole-genome comparisons. Comparison to the phylogeny of enterotoxin genes uncovered ample evidence for horizontal transfer of hbl, cytK and plcR, as well as frequent deletion of both toxins and duplication of hbl. No evidence for nhe deletion was found and stable horizontal transfer of nhe is rare. Therefore, evolution of B. cereus enterotoxin operons is shaped unexpectedly different for yet unknown reasons.


Frequent exchange of the pathogenicity factors hbl, cytK and plcR in B. cereus sensu lato appears to be an important mechanism of B. cereus virulence evolution, including so-called probiotic or non-pathogenic species, which might have consequences for risk assessment procedures. In contrast, exclusively vertical inheritance of nhe was observed, and since nhe-negative strains appear to be extremely rare, we suggest that fitness loss may be associated with deletion or horizontal transfer of the nhe operon


Stellenausschreibung Doktorandenstelle
Doktorand/in in molekularer Mikrobiologie zum Thema Funktion und Evolution überlappender Gene in Bakterien

Innovationspreis für Siegfried Scherer

Otto-von-Guericke Forschungspreis für Siegfried Scherer

Denkvoraussetzungen und weltanschauliche Überzeugungen in der Biologie (2017)

Differentiation of ncRNAs from small mRNAs in Escherichia coli O157:H7 EDL933 (EHEC) by combined RNAseq and RIBOseq-ryhB encodes the regulatory RNA Ryhb and a Peptide, RyhP. (2017)

Complete circular genome sequence and temperature independent adaptation to Anaerobiosis of Listeria weihenstephanensis DSM 24698 (2017)

Discovery of numerous novel small genes in the intergenic regions of the Escherichia coli O157:H7 Sakai Genome (2017)

High binding affinity of repressor IolR avoids costs of untimely induction of myo-inositol utilization by Salmonella Typhimurium (2017)

Genetic characterization of the Galactitol utilization pathway of Salmonella enterica serovar Typhimurium. (2017)

Heat stability of indigenous milk plasmin and peptidases from Pseudomonas: a challenge in the production of ultra-high temperature milk products (2016)

Spoilage of Microfiltered and Pasteurized Extended Shelf Life Milk Is Mainly Induced by Psychrotolerant Spore-Forming Bacteria that often Originate from Recontamination (2017)

Bakterieller Stoffwechsel als Pathogenitätsfaktor (2016)

Transcriptional and translational regulation by RNA thermometers, riboswitches and the sRNA DsrA in Escherichia coli O157:H7 Sakai under combined cold and osmotic stress adaptation. (2016)

Hysteresis in myo-inositol utilization by Salmonella Typhimurium (2016)

Probiotic Enterococcus faecalis Symbioflor® down regulates virulence genes of EHEC in vitro and decrease pathogenicity in a Caenorhabditis elegans model (2017)

Draft Genome Sequence of Lysinibacillus xylanilyticus SR-86 (Nov. 2016)

Permanent colonization of creek sediments, creek water and limnic water plants by four Listeria species in low population densities (November 2016)

Draft Genome Sequence of the Xanthan Producer Xanthomonas campestris LMG 8031 (Oktober 2016)

Comparative Bioinformatics and Experimental Analysis of the Intergenic Regulatory Regions of Bacillus cereus hbl and nhe Enterotoxin Operons and the Impact of CodY on Virulence Heterogeneity (Mai 2016)

Regulation of fucose and 1,2-propanediol utilization by Salmonella enterica serovar Typhimurium (März 2016)

Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method (März 2016)

Berufung Expertenrat
Prof. Dr. Siegfried Scherer wurde in den Expertenrat für Lebensmittelsicherheit des Bayerischen Staatsministeriums für Umwelt und Verbraucherschutz berufen.

Translatomics combined with transcriptomics and proteomics reveals novel functional, recently evolved orphan genes in Escherichia coli O157:H7 (EHEC)

A sensitive and robust method for direct determination of lipolytic activity in natural milk environment (März 2016, online first)

Evidence for the recent origin of a bacterial protein-coding, overlapping orphan gene by evolutionary overprinting (Dez. 2015).

Massive horizontal gene transfer, strictly vertical inheritance and ancient duplications differentially shape the evolution of Bacillus cereus enterotoxin operons hbl, cytK and nhe (Nov. 2015)

Chemodiversity of cereulide, the emetic Toxin of Bacillus cereus (2015)