Facultative anaerobic pathogens such as Escherichia coli thrive in environments depleted from oxygen thank to a versatile anaerobic respiration system. This means that they can use the so-called alternative electron acceptors (AEAs) such as nitrate, fumarate, and others, to replace oxygen in the respiratory electron transport chain. This adaptive physiological feature enables the colonization of primarily anaerobic niches in the environment as well as within a host (e.g. the gut) [1]. This is the case of enterotoxigenic E. coli (ETEC), a pernicious, globally-spread pathogen that colonizes the human intestinal tract, causing diarrhea.

Recent evidence suggest a pivotal role of anaerobic physiology in host colonization and virulence regulation in pathogenic E. coli, including ETEC [1-2]. One of such virulence factors is ETEC attachment to the intestinal tract epithelium and biofilm formation [3]. We have shown that certain AEAs modulate biofilm development in ETEC. Therefore, the goal of this project will be to explore the transcriptional and protein expression changes induced by AEA supplementation in ETEC biofilms, and to probe the role of respiration in bacterial adhesion to intestinal cells. The student will have the chance to learn and use a number of techniques:

-Molecular genetics: mutant preparation using lamba-red recombineering, molecular cloning.
-Transcriptional analyses: RNA isolation, qPCR, RNA-seq.
-Protein expression analyses: SDS-PAGE, Western Blot, proteomics.
-Basic bioinformatic analyses (upon RNA-seq data delivery).
-Cell culture and infection, including microscopy.
-Anaerobic tests involving work under an anaerobic chamber.

The project will be based at the Sjöling group, Center for Translational Microbiome Research, and will benefit from the facilities and expertise available at the Center.

References:

[1] González-Siles and Sjöling. The different ecological niches of enterotoxigenic Escherichia coli. Environ Microbiol. 2016; 18(3):741-51.
[2] Martín-Rodríguez, Melican, Rhen and Richter-Dahlfors. Nitrate metabolism modulates the biosynthesis of biofilm components in uropathogenic Escherichia coli and is a fitness factor during experimental urinary tract infection. mBio (under review).
[3] Rossi, Cimdins, Lüthje, Baruner, Sjöling, Landini and Römling. "It's a gut feeling" - Escherichia coli biofilm formation in the gastrointestinal tract environment. Crit Rev Microbiol. 2018; 44(1):1-30