The combination of distance-based and sequence-based methods applied to 238 genomes showed that the Lactobacillus genus was polyphyletic, intermixed with other genera and characterized by a complex evolutionary history, confirming also previous findings on limited sets of data. The data irrefutably indicate that the extraordinarily diverse genus Lactobacillus should be sub-divided into more homogeneous genera whose members share similar evolutionary events, characterised by uniform patterns of presence/absence of specific sets of genes.
The full analysis of the mechanisms of action are required by EFSA for the approval of probiotic claims and clinical use of probiotics. We investigated the presence of the gene coding for an immunomodulatory protein the soluble p40 protein in all lactobacilli and we found out that 24 Lactobacillus genomes harbour the gene of interest and seven of them are able to produce the protein and release it in the supernatants.
Besides health-promoting traits, we also improved the knowledge about the antibiotic resistance (AR) genes in the Lactobacillus genus, by determining the antibiotic susceptibility patterns of 196 strains from the phenotypic and genotypic point of view. As for the phenotypic analysis, lactobacilli MIC of 16 antibiotics have been determined with vet-MIC plates; on the second hand, the comparative genomics analysis mainly consisted in BLAST searches against CARD database and the investigation of the genetic organization of the putative AR genes and their associated resistance mechanisms. This study, carried out in collaboration with Teagasc Food Research Centre (Fermoy, Ireland) and University of Verona, is expected to be used as a new guideline for the use of lactobacilli as starter cultures, food preservatives or probiotic bacteria by food and probiotic stakeholders and legislative bodies.
During the secondment in Chr. Hansen A/S, data obtained within the first part of GENOLACT contributed to the whole genome sequence strain typing process in the Strain Supply Chain and to develope a new Multilocus Sequence Typing Scheme. Further, activities in Chr. Hansen included thorough safety assessment of a potential Lactobacillus probiotic strain through MIC determination as requested by EFSA along with a comparative genomic study of 30 closely related strains of three different Lactobacillus species.
In the whole, I published 2 peer-reviewed papers and 6 posters, I participated to 5 conferences, I gave 4 oral presentations, I contributed as a volunteer to 7 activities related to public engagement, and I attended 9 sessions organised by UCC regarding research management and complementary skills development. Furthermore, I participated to other 3 training courses (in Sweden, Germany and UK) on technology transfer, intellectual property management and regulatory affairs in Europe.