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Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL)

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

 Infection strategies of gut pathogens
Group leader: Prof. Dr. Thilo M. Fuchs

Prof. Fuchs moved to the Institut of Molecular Pathogenesis of the Friedrich-Loeffler-Institut in Jena by Jan 2017 

My research focus is on the molecular characterization of virulence properties and metabolic pathways by which the bacterial pathogens Salmonella typhimurium, Listeria monocytogenes and Yersinia enterocolitica successfully adapt to their intracellular and extracellular environment. The molecular analyses are performed by pangenomic approaches, genome comparison, multiple and genome-wide screens, genome libraries, luciferase-based reportering, fluorescence microscopy, expression profiling, phenotype microarrays, in frame-gene deletions, biochemical assays, host infection assays, imaging systems and 13C-isotopologue analysis (in cooperation with W. Eisenreich, Garching). Eukaryotic cell cultures, insects, insect larvae, Caenorhabditis elegans, amoeba and mice are used as host systems.


Insecticidal activity of Yersinia enterocolitica
Coworker: M.Sc. Katharina Brauer

Y. enterocolitica is a foodborne pathogen that causes gastroenteric disease in man. Recently, we could for the first time demonstrate the insecticidal activity of Y. enterocolitica. The so-called toxin-complex genes responsible for lethality towards insects are localised on a novel pathogenicity island, tc-PAIYe, which is also present in the genome of Y. pestis. A specific feature of these toxins, which are an alternative to the toxin of Bacillus thuringiensis-toxin, is their temperature-dependent expression. Using the luciferase reporter system, we could demonstrate that Y. enterocolitica expresses the Tc proteins at 10°C, but not at 37°C. Together with further data on temperature-dependent gene expression, this suggests the temperature-driven oscillation of Y. enterocolitica between two distinct pathogenicity phases that allow the infection of invertebrates at ambient temperatures and the infection of mammals at body temperature. A genome comparison between Y. enterocolitica und and the insect pathogen Photorhabdus shed further light on the evolution of yersiniae. In our genome-based studies, we are interested in the regulatory network underlying the temperature-dependent toxin expression, in the molecular mechanisms involved in toxin release, in the mechanism by which the insecticidal toxin damages eukaryotic cells, and in novel, yet uncharacterised genetic determinants contributing to pathogenicity of yersiniae.

Metabolism of Listeria monocytogenes: contributions to virulence 
Mitarbeiter: M. Sc. Jakob Schardt

The natural habitat of Listeria spp. is the surface layer of soil rich in decaying plant matter. Using contaminated food as a vehicle, the bacteria gain access to the human host via the oral route. The two pathogenic species L. monocytogenes and L. ivanovii are facultative intracellular parasites that are able to proliferate within macrophages and nonphagocytic cells such as epithelial cells and hepatocytes. Most virulence factors responsible for key steps in this life cycle have been identified and characterized during the last years. However, little is known about the metabolic capabilities of listeriae required for a successful infection. In close cooperation with W. Eisenreich (Garching), we recently applied isotopologue analysis to measure the metabolic fluxes of intra- and extracellularly growing L. monocytogenes. The isotopologue profiles derived from the utilization of labelled carbon and nitrogen sources allowed further conclusions about the compartment-specific metabolism of L. monocytogenes. Currently, we investigate which metabolic capacities enable listeriae to overcome the colonization resistance in the gut.





PhD student position by end of October 2017 Adaptation and Constraint in the Evolution of Overlapping Genes

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

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)

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)