Prof. Dr. Marc Erhardt

Molecular Microbiology Group

The incidence of foodborne outbreaks caused by Enterobacteriaceae, including Salmonella enterica, remains substantial and constitutes a significant socioeconomic burden in Europe and worldwide. This is evidenced by the inclusion of Salmonella in the list of priority pathogens, which was recently published by the World Health Organization (WHO) to highlight urgent public health needs.

Salmonella enterica are motile, intracellular pathogens that employ multiple virulence factors, including flagella and needle-like injectisome devices, to efficiently colonize the host. The flagellum and injectisome are complex self-assembling nanomachines and their function relies on protein export via a conserved type-III secretion system. However, the molecular details of protein secretion via the type-III export apparatus remains largely obscure. In addition, complex regulatory mechanisms control the biosynthesis of the flagellum and virulence-related injectisome and substantial transcriptional cross talk between the various virulence factors exists that is poorly understood.

The research of the Erhardt Lab concerning the molecular mechanisms of these fascinating nanomachines, in particular of the self-assembling bacterial flagellum, allows them to address fundamental research questions in microbiology and bacterial physiology, such as:

What are the molecular mechanisms of flagellum assembly and of the type-III protein secretion process?
What is the role of flagella and bacterial motility in the infection process?
How does Salmonella regulate its gene expression profile to adapt to diverse and hostile environments inside the host?

Elucidating the molecular mechanisms of the bacterial type-III protein secretion system and the life-style transition from the motile, planktonic state in the intestinal lumen to intracellular growth after invasion of the epithelium will be essential for a detailed understanding of the events required for the commitment of the bacteria to invasive diseases. Importantly, an in-depth knowledge of these mechanisms could be used to design rational strategies that counter the spread of gastrointestinal infections – urgently needed at a time when antibiotic resistance is increasing.

Bacterial genetics
Fluorescent microscopy
TIRF microscopy
STED superresolution microscopy
Microfluidics
Single cell analyses

Current position

2023 - present	Full professor of Molecular Microbiology at the Humboldt-Universität zu Berlin (DE)
2021 - present	Max Planck Fellow at the Max Planck Unit for the Science of Pathogens, Berlin (DE)

Positions held

2017 - 2023	Associate professor of Bacterial Physiology at the Humboldt-Universität zu Berlin (DE)
2013 - 2017	Principal Investigator of an independent present junior research group at the Helmholtz Centre for Infection Research, Braunschweig (DE)
2011 - 2012	Postdoctoral Researcher at the Université de Fribourg (CH)

Academic Education

2007 - 2011	Doctoral Degree in Microbiology at the Universität Konstanz (DE); Universität Heidelberg (DE); University of Utah (US); Université de Fribourg (CH)
2004 - 2006	Master’s Degree in Microbiology and Biochemistry at the Universität Konstanz (DE); University of Utah (US)
2002 - 2004	Bachelor’s Degree in Biology at the Universität Ulm (DE)

Honors/Awards/Fellowships

2020	ERC Consolidator Grant
2018	Forschungspreis der Vereinigung für Allgemeine und Angewandte Mikrobiologie (VAAM)
2013 - 2017	Helmholtz Young Investigator grant
2012 - 2013	Marie Curie International Incoming Fellowship
2012	Elisabeth-Gateff-Prize of the Gesellschaft für Genetik
2012	EMBO Long-Term Fellowship - declined
2007 - 2010	Boehringer Ingelheim Fonds Ph.D. fellowship
2010	DeLill Nasser Award of the Genetics Society of America
2005 - 2007	Studienstiftung des deutschen Volkes

DFG-funded projects

2016 - present	Research Grant - 'Quality management in assembly of bacterial type III secretion systems – a comparative analysis of the construction of flagella and injectisomes'
2016 - 2021	Research Grant - 'Function of the type-III secretion system ATPase complex in protein export of the bacterial flagellum'
2019	Major Research Instrumentation - 'Superresolution stimulated emission-depletion (STED) microscope'

Selected activities

2023 - present	Managing director of the Institute of Biology, Humboldt-Universität zu Berlin (DE)
2022 - present	Instructor of the Advanced Bacterial Genetics (ABG) Course at Cold Spring Harbor Laboratory (USA)
2021 - present	Elected member of the steering committee of the Institute of Biology, Humboldt-Universität zu Berlin (DE)
2021 - present	Member of the review committee of the Faculty of Life Sciences for special merit awards, Humboldt-Universität zu Berlin (DE)
2022	Organizer of the 4th VAAM discussion meeting 'Microbial Cell Biology', Berlin (DE)
2022 - 2023	Deputy director of the Institute of Biology, Humboldt-Universität zu Berlin (DE)
2022 - 2023	Head of the examination committee of the Institute of Biology, Humboldt-Universität zu Berlin (DE)
2017 - 2020	Scientific Advisory Board member, T3S Technologies, Inc., 36 S. Wasatch Drive, SMBB Box 3, Salt Lake City, Utah 84112, USA

Selected publications

Goldlust K, Ducret A, Halte M, Dedieu-Berne A, Erhardt M, Lesterlin C. The F pilus serves as a conduit for the DNA during conjugation between physically distant bacteria. Proc Natl Acad Sci U S A. 2023 Nov 21;120(47):e2310842120. doi: 10.1073/pnas.2310842120.
Saleh DO, Horstmann JA, Giralt-Zúñiga M, Weber W, Kaganovitch E, Durairaj AC, Klotzsch E, Strowig T, Erhardt M. SPI-1 virulence gene expression modulates motility of Salmonella Typhimurium in a proton motive force- and adhesins-dependent manner. PLoS Pathog. 2023 Jun 14;19(6):e1011451. doi: 10.1371/journal.ppat.1011451.
Hu H, Popp PF, Santiveri M, Roa-Eguiara A, Yan Y, Martin FJO, Liu Z, Wadhwa N, Wang Y, Erhardt M, Taylor NMI. Ion selectivity and rotor coupling of the Vibrio flagellar sodium-driven stator unit. Nat Commun. 2023 Jul 27;14(1):4411. doi: 10.1038/s41467-023-39899-z.
Guse A, Halte M, Hüsing S, Erhardt M. Hook-basal-body assembly state dictates substrate specificity of the flagellar type-III secretion system. Mol Microbiol. 2021 Oct;116(4):1189-1200. doi: 10.1111/mmi.14805.
Hüsing S, Halte M, van Look U, Guse A, Gálvez EJC, Charpentier E, Blair DF, Erhardt M, Renault TT. Control of membrane barrier during bacterial type-III protein secretion. Nat Commun. 2021 Jun 28;12:3999. doi: 10.1038/s41467-021-24226-1.
Santiveri M, Roa-Eguiara A, Kühne C, Wadhwa N, Hu H, Berg HC, Erhardt M, Taylor NMI. Structure and Function of Stator Units of the Bacterial Flagellar Motor. Cell. 2020 Oct 1;183(1):244-257.e16. doi: 10.1016/j.cell.2020.08.016.
Horstmann JA, Lunelli M, Cazzola H, Heidemann J, Kühne C, Steffen P, Szefs S, Rossi C, Lokareddy RK, Wang C, Lemaire L, Hughes KT, Uetrecht C, Schlüter H, Grassl GA, Stradal TEB, Rossez Y, Kolbe M, Erhardt M. Methylation of Salmonella Typhimurium flagella promotes bacterial adhesion and host cell invasion. Nat Commun. 2020 Apr 24;11(1):2013. doi: 10.1038/s41467-020-15738-3.
Spöring I, Martinez VA, Hotz C, Schwarz-Linek J, Grady KL, Nava-Sedeño JM, Vissers T, Singer HM, Rohde M, Bourquin C, Hatzikirou H, Poon WCK, Dufour YS, Erhardt M. Hook length of the bacterial flagellum is optimized for maximal stability of the flagellar bundle. PLoS Biol. 2018 Sep 6;16(9):e2006989. doi: 10.1371/journal.pbio.2006989.
Renault TT, Abraham AO, Bergmiller T, Paradis G, Rainville S, Charpentier E, Guet CC, Tu Y, Namba K, Keener JP, Minamino T, Erhardt M. Bacterial flagella grow through an injection-diffusion mechanism. Elife. 2017 Mar 6;6:e23136. doi: 10.7554/eLife.23136.
Fabiani FD, Renault TT, Peters B, Dietsche T, Gálvez EJC, Guse A, Freier K, Charpentier E, Strowig T, Franz-Wachtel M, Macek B, Wagner S, Hensel M, Erhardt M. A flagellum-specific chaperone facilitates assembly of the core type III export apparatus of the bacterial flagellum. PLoS Biol. 2017 Aug 3;15(8):e2002267. doi: 10.1371/journal.pbio.2002267.