Final Report sent to UEFISCDI

On the 31^st of October the project ended. A report presenting the activities performed in 2019 and a Summary of the three year project achievements were sent to UEFISCDI, the institution that financially supported SafeFood.

The mutant ΔLmo2229 was obtained

A mutant of L. monocytogenes EGDe strain was obtained. The mutant  lacks the Lmo2229 gene, which codifies for the penicillin-binding protein 1F. We are going to test this strain to high hydrostatic pressures to see how it reacts in comparison with the non-mutant strain.

Writing a book chapter

Our group started to write a chapter on Biofilms in Food and Food Processing Environments that incorporates some of the findings from this project. The Chapter will be part of the book Bacterial Biofilms that will be published by IntechOpen.

Continuing working on mutants

We restarted the process of obtaining mutants. This time our target was to eliminate the Lmo2229 gene from the genome of L. monocytogenes EGDe to be able to reveal one of the mechanisms that this bacterium is using to recover after HPP treatments.

HPP experiment repeated for gene sequencing.

The experiment of submitting two HPP resistant L. monocytogenes strains, RO15 and Scott A, to high pressure treatments and following their recovery was repeated and a new strain (S2542) was incorporated in the experiment, which aims to reveal the genes involved in the resistance mechanisms of L. monocytogenes to high pressure processing. Cropped cells were stabilized with RNAprotect^® and sent to the Finish partner for gene sequencing.

Inventory of the project’s results at the 3rd Annual Meeting of the SafeFood Consortium

An inventory of the project’s results was made and modalities to combine them for publication were discussed during the Annual Meeting of the SafeFood Consortium, which was held on the 7^th and 8^th of May 2019, in Porto, Portugal.

Discriminating between live and dead cells of L. monocytogenes

Our first attempts of using CLSM (Confocal Light Scanning Microscopy) for discriminating between live and dead cells of L. monocytogenes were performed in order to see how different HPP treatments have an impact on cells viability.

Manuscript published

We were announced that our manuscript "Characterization of the biofilm phenotype of a Listeria monocytogenes mutant deficient in agr peptide sensing" was accepted for publication in Microbiology Open.

Manuscript revised

Reviewers of the manuscript entitled "Characterization of the biofilm phenotype of a Listeria monocytogenes mutant deficient in agr peptide sensing", which was sent to Microbiology Open, asked for some supplementary tests to support our statements. After performing the requested tests, the manuscript was resubmitted.

List of genes for knock-outs/knock-downs in L. monocytogenes

Based on RNA sequencing, our Finish partners from the University of Helsinki provided a list of genes that they consider being good candidates for knock-outs/knock-downs in L. monocytogenes and the annotated peptidoglycan biosynthesis pathway for both L. monocytogenes strains that we are working on in the SafeFood project. This allows us to try obtaining new L. monocytogenes mutants.