Effect of pre-acclimation medium on cell viability, membrane integrity and malolactic fermentation of lactobacillus plantarum inoculated in synthetic wine

BRAVO-FERRADA B; GOMEZ ZAVAGLIA, A.; SEMORILE L; TYMCZYSZYN E,

Tucuman

Simposio; IV Simposio Internacional de Bacterias Lácticas (SIBAL). Alimentos, Salud y Aplicaciones; 2013

CERELA

Lactobacillus plantarum has been described as one of the LAB species responsible for malolactic fermentation in winemaking. Due the stress factors present in wine (low pH, high ethanol concentration, etc.), starter cultures shall be previously acclimated. The aim of this work was to evaluate the effect of acclimation on the viability, membrane integrity and technological properties of three oenological strains of Lact. plantarum exposed to wine conditions. Cultures in the exponential phase were inoculated in an acclimation medium containing 0, 6 and 10% v/v ethanol and incubated 48 h at 28 °C. After incubation, cells were harvested by centrifugation and inoculated in a synthetic wine, containing 14% v/v ethanol and pH 3.5. The membrane integrity and viability were measured by flow cytometry using two fluorescent dyes: propidium iodide (PI) and carboxyfluorescein diacetate (cFDA). Strains previously acclimated were inoculated in synthetic wine and incubated at 28 ºC without shaking. Cultivability and L-malic acid consumption were monitored during 15 days. In non-acclimated strains, the damage of bacterial membranes produced a rapid increase of PI uptake. At the same time, a noticeable decrease of microbial viability was observed. Acclimation in both 6% and 10% v/v ethanol, noticeable increased the microbial viability of all strains in synthetic wine, and contributed to maintain the membrane integrity. The evolution of viability and malolactic fermentation of acclimated strains, grown 15 days in synthetic wine, showed the high effectiveness of pre-acclimation at 10% v/v ethanol. Acclimation of oenological strains in media containing ethanol prior to inoculation of wines significantly improves the viability and decreases the membrane damage in the harsh wine conditions. These results represent a contribution for the development of LAB starter cultures for winery.