Effect of protective agents and previous acclimation on ethanol resistance of frozen and freeze-dried lactobacillus plantarum strains

BÁRBARA MERCEDES BRAVO-FERRADA1; NATALIA BRIZUELA; ESTEBAN GERBINO; ANDREA GOMEZ-ZAVAGLIA; LILIANA SEMORILE; E. ELIZABETH TYMCZYSZYN

CRYOBIOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2015 vol. 71 p. 522 - 528

0011-2240

The aim of this work was to study theprotective effect of sucrose, trehalose and glutamate during freezing andfreeze-drying of three oenological L.plantarum strains previously acclimated in the presence of ethanol. Theefficiency of protective agents was assessed by analyses of membrane integrityand bacterial cultivability in a synthetic wine after the preservationprocesses. No significant differences in the cultivability, with respect to thecontrols cells, were observed after freezing at -80 ºC and -20 ºC, andpre-acclimated cells were more resistant to freeze-drying than non-acclimatedones. The results of multiparametric flow cytometry showed a significant levelof membrane damage after freeze-drying in two of the three strains. The cultivability was determined after incubation in wine-like medium containing 13or 14% v/v ethanol at 21 °C for 24 h and the results were interpreted usingprincipal component analysis (PCA). Acclimation was the most important factorfor preservation, increasing the bacterial resistance to ethanol after freezingand freeze-drying. Freeze-drying was the most drastic method of preservation,followed by freezing at -20 °C. The increase of ethanol concentration from 6 to10% v/v in the acclimation medium improved the recovery of two of the threestrains. In turn, the increase of ethanol content in the synthetic wine led toa dramatic decrease of viable cells in the three strains investigated. Theresults of this study indicate that a successful inoculation of dehydrated L. plantarum in wine depends not only onthe use of protective agents, but also on the cell acclimation process prior topreservation, and on the ethanol content of wine.