Vljudno vabljeni na predavanje “Social interactions in complex microbial communities – Survival of the fittest or the friendliest?” predavatelja prof.  Søren J. Sørensen (Section of Microbiology, Department of Biology, University of Copenhagen)

Predavanje bo v četrtek, 19.9. 2013 ob 13:00 v predavalnici B5, Biološko središče, Večna pot 111.

POVZETEK PREDAVANJA:

Multispecies biofilms are predominant in almost all natural environments, setting the scene for various competitive and cooperative interactions that affect overall functionality and fitness of the individual strains and the community.

We have developed a model defining synergism, antagonism and neutrality within multispecies biofilms, based on the proportion of the species that are present and their ability to form monospecies biofilm. The model was validated experimentally in control systems of isogenic strains differing only in their ability of biofilm formation as single species. We applied this model to characterize the interactions in multispecies biofilm formation of bacterial consortia isolated from a variety of natural habitats.

Furthermore we have developed a simple assay for screening of antagonistic interactions among bacterial isolates. This approach was used to investigate the number of antagonistic interactions among bacteria co-isolated from the same environmental sample in comparison to interactions between isolates from different environments.

Recent research has revealed that bacterial plasmids and biofilm formation are interconnected in many ways. Horizontal transfer rates are typically higher in biofilm communities compared with those in planktonic states. Biofilms, furthermore, promote plasmid stability and may enhance the host range of mobile genetic elements that are transferred horizontally. Plasmids, on the other hand, are very well suited to promote the evolution of social traits such as biofilm formation. This, essentially, transpires because plasmids are independent replicons that enhance their own success by promoting inter-bacterial interactions. They typically also carry genes that heighten their hosts’ direct fitness. I present a couple of examples from our most recent research of how plasmids can promote biofilm formation in natural environments and reveal some of the molecular mechanisms behind this phenomenon.

In conclusion, we present results indicating ubiquity of synergism in multispecies biofilm formation in complex bacterial communities.