At the Chair of Microbiology we share interests in bacterial physiology and molecular mechanisms that drive bacterial interactions. Capitalizing on diversity of our research backgrounds we complement classical microbiology methods with molecular microbiology, single cell and 3D imaging, quantitative image analysis, biochemistry, biophysics tools, mathematical modelling or comparative genomics.

We study microbial ecosystems at several levels of organization from single cells and their responses to local environments, up to cell-cell interactions within clonal populations (Sretanovic et al., 2017; Spacapan et al., 2018; Dogsa et al., 2021), interactions between different strains of one species (Oslizlo et al., 2015; Stefanic et al., 2015; Lyons et al., 2016; Stefanic et al., 2021; Kreigher et al., 2021), as well as in multispecies communities, where the ‘good’ bacteria are challenged against pathogens (Erega et al., 2021). We also ask how bacterial physiology or ecology can be shaped by phages (Dragos et al., 2020; Dragos et al., 2021).

We work with microbes of biotechnological relevance such as Bacillus subtilis, Campylobacter jejuni, Salmonella enterica serovar Typhimurium, under ecologically-relevant experimental setups, for instance multilayer assemblies called biofilms. We are trying to understand the initial attachment of biofilm founders to surfaces, control of biofilm growth and development and temporal changes in its viscoelastic properties (Horvat et al., 2019; Spacapan et al., 2019; Simunič et al., 2020; Terlep et al., 2021). We have also established a model system to study bacterial self-recognition, a process known as kin discrimination, using soft-surface swarming model (Stefanic et al., 2015; Lyons et al., 2016). Next to molecular mechanisms behind this process, we are interested how kin discrimination impacts behaviors in heterogenous groups, special segregation of genotypes, horizontal gene transfers or production and sharing of secreted molecules (enzymes, polysaccharides or toxins/antibiotics) (Stefanic et al., 2021; Kreigher et al., 2021).

While motivated by basic scientific questions, we actively seek for applications for our discoveries in different fields of biotechnology, e.g. food industry (patent), wastewater technology (Kreigher & Mandic-Mulec, 2020) or biomedicine.

Figure 1: Kin discrimination in the Bacillus subtilis and its potential applications.

Figure 2: On the right: The mixture of two fluorescently labeled B. subtilis strains was inoculated into the liquid growth medium. The pellicle formed after 16h shows segregation of the two strains into purple and blue clusters. On the left: A microfluidic device designed to capture growing B. subtilis cells. The elongated bacterial chains occupied the available space.

Figure 3: Interactions between B. subtilis (red) and Salmonella enterica serovar Typhimurium (green) on TSB solid medium. The figure shows the interactions after 48 h of cultivation, where we see the invasion of B. subtilis into the colony of S. Typhimurium - we assume that B. subtilis synthesizes antimicrobial compounds that cause lysis of S. Typhimurium cells