The first step was to understand whether epibionts are host specific. Using extensive field data, we demonstrated that the bacterial communities associated to rotifers, cladocerans, copepods, sediments, stones, and in water at different depths in a lake were coherently similar within and significantly different between substrates.
Then, we explored the degree of association between the microbiota and the hosts: we found that for cladocerans, copepods, and cyanobacteria such association is present, whereas no association was found for rotifers. We highlighted unexpected differences in the host-epibiont relationships.
After the descriptive part to explore the degree of association, we moved to more functional analyses, analysing potential processes driving the presence of bacteria on biofilms and the role they have in the potential spread of pathogens and/or antibiotic resistance genes. We used different models systems, including bacteria associated to zooplankton, in biofilms associated to living organisms (e.g. rotifers, crustaceans, corals, etc.), in biofilms on microplastics, etc. We discovered that:
- cladocerans can act as a refuge for antibiotic resistance genes selected under anthropogenic pressure;
- biofilms on microplastics increase the potential for the spread of antibiotic resistance;
- anthropogenic pollution and ecological factors interact in driving the persistence of antibiotic resistance genes in freshwater environments and in host-associated biofilms;
- microbial associations interfere with the recruitment of coral colonies;
- species coexistence and predation may promote microbial diversity;
- antibiotic disturbance affects aquatic microbial community composition and phenotypic distribution of cells but not diversity and stability of the communities
For each of the main results we obtained we prepared scientific manuscripts for submission. Some of them are already accepted, and others are still under review. Most of the results were also presented at international conferences to allow a broad range of researchers getting in contact with us. Moreover, we presented some of the results during local events and conferences to the public at our host institute in Verbania Pallanza, Italy. All the genetic information produced during the project was deposited or will be deposited in online repositories, e.g. GenBank.
