Prof. Dr. Marc Erhardt

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:

1. What are the molecular mechanisms of flagellum assembly and of the type-III protein secretion process?
2. What is the role of flagella and bacterial motility in the infection process?
3. 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.