MEDIA PHOSPHATE CONTENT INFLUENCES STRESS TOLERANCE AND BIOFILM FORMATION OF Lactobacillus paraplantarum CRL 1905

VILLEGAS, J.M.; ARAOZ, M.; GRILLO-PUERTAS, M.; HEBERT, E. M.; RAPISARDA, V.

Congreso; LIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2017

Lactic acidbacteria (LAB) comprise a group of Gram positive microorganisms commonly usedin food fermentation industry. They are usually exposed to a range of stressfulenvironmental conditions in both natural and/or industrial habitats, such ashigh temperature, low pH, nutrient starvation, and oxidation. Previous studies showedthat media phosphate (Pi) content modulates polyphosphate (polyP) levels indifferent bacteria, affecting stress responses, stationary-phase survival, andbiofilm formation. The aim of this work was to investigate the effect of Piconcentrations on stress resistance and biofilm formation of L. paraplantarumCRL 1905. Intracellular polyP levels of the strain grown in chemically definedmedia (CDM) containing different Pi concentrations were determined. As control,CRL 1905 was grown in the routinely used rich medium MRS. It was observed thathigh polyP levels were maintained up to 120 h only when cells were grown in CDMsupplied with 60 mM Pi. The polyp accumulation under this condition wascorrelated with a long-term cell survival, when compared to cells grown in CDMmedium supplemented with sufficient Pi; loss of viability over time was evenmore pronounced in the rich medium. CRL 1905 stationary-phase cells grown in 60mM Pi were more tolerant to high temperatures than those grown in 2 mM Pi.However, there was no correlation between media Pi concentration and resistanceto acidic and oxidant conditions. The biofilm-forming capacity of L.paraplantarum under different culture conditions was characterized bymicrotiter plate biofilm assays. It was observed that a high Pi concentrationin the medium impaired biofilm formation; this phenotype could be related tothe maintenance of polyP in stationary phase. Taken together, this study contributesto a better understanding of alternative mechanisms by which beneficialbacteria can counteract several stress conditions and colonize differentniches.Keywords:Lactic acid bacteria; polyphosphate; stress tolerance; biofilm formation