New Insights into the Anti-pathogenic Potential ofLactococcus garvieaeagainstStaphylococcus aureusBased on RNA Sequencing Profiling.
The bio-preservation potential ofLactococcus garvieaelies in its capacity to inhibit the growth ofstaphylococci, especiallyStaphylococcus aureus, in dairy products andin vitro.In vitro, inhibition is modulated by the level of aeration, owing to hydrogen peroxide (H2O2) production byL. garvieaeunder aeration. TheS. aureusresponse to this inhibition has already been studied. However, the molecular mechanisms ofL. garvieaeunderlying the antagonism againstS. aureushave never been explored. This study provides evidence of the presence of another extracellular inhibition effectorin vitro. This effector was neither a protein, nor a lipid, nor a polysaccharide, nor related to an L-threonine deficiency. To better understand the H2O2-related inhibition mechanism at the transcriptome level and to identify other mechanisms potentially involved, we used RNA sequencing to determine the transcriptome response ofL. garvieaeto different aeration levels and to the presence or absence ofS. aureus. TheL. garvieaetranscriptome differed radically between different aeration levels mainly in biological processes related to fundamental functions and nutritional adaptation. The transcriptomic response ofL. garvieaeto aeration level differed according to the presence or absence ofS. aureus. The higher concentration of H2O2with high aeration was not associated with a higher expression ofL. garvieaeH2O2-synthesis genes (pox,sodA, andspxA1) but rather with a repression ofL. garvieaeH2O2-degradation genes (trxB1,ahpC,ahpF, andgpx). We showed thatL. garvieaedisplayed an original, previously undiscovered, H2O2production regulation mechanism among bacteria. In addition to the key factor H2O2, the involvement of another extracellular effector in the antagonism againstS. aureuswas shown. Future studies should explore the relation between H2O2-metabolism, H2O2-producing LAB and the pathogen they inhibit. The nature of the other extracellular effector should also be determined.
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Pierre
P
Delpech
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Etienne
E
Rifa
John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University Nottingham, UK.
Graham
G
Ball
Montpellier GenomiX, Institut de Génomique Fonctionnelle Montpellier, France.
Sabine
S
Nidelet
Montpellier GenomiX, Institut de Génomique Fonctionnelle Montpellier, France.
Emeric
E
Dubois
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Geneviève
G
Gagne
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Marie-Christine
MC
Montel
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Céline
C
Delbès
Université Clermont Auvergne, INRA, UMRF Aurillac, France.
Stéphanie
S
Bornes
Lactococcus garvieae; Staphylococcus aureus; anti-pathogenic interactions; growth inhibition; hydrogen peroxide; transcriptome