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

Autor: Bravo-Ferrada BM; Laboratory of Molecular Microbiology, Department of Science and Technology, Universidad Nacional de Quilmes, Bernal, Argentina., Brizuela N; Laboratory of Molecular Microbiology, Department of Science and Technology, Universidad Nacional de Quilmes, Bernal, Argentina., Gerbino E; Center for Research and Development in Food Cryotechnology (CIDCA) CCT- La Plata, RA-1900, Argentina., Gómez-Zavaglia A; Center for Research and Development in Food Cryotechnology (CIDCA) CCT- La Plata, RA-1900, Argentina., Semorile L; Laboratory of Molecular Microbiology, Department of Science and Technology, Universidad Nacional de Quilmes, Bernal, Argentina., Tymczyszyn EE; Laboratory of Molecular Microbiology, Department of Science and Technology, Universidad Nacional de Quilmes, Bernal, Argentina. Electronic address: elitym@yahoo.com.ar.
Jazyk: angličtina
Zdroj: Cryobiology [Cryobiology] 2015 Dec; Vol. 71 (3), pp. 522-8. Date of Electronic Publication: 2015 Nov 14.
DOI: 10.1016/j.cryobiol.2015.10.154
Abstrakt: The aim of this work was to study the protective effect of sucrose, trehalose and glutamate during freezing and freeze-drying of three oenological Lactobacillus plantarum strains previously acclimated in the presence of ethanol. The efficiency of protective agents was assessed by analyses of membrane integrity and bacterial cultivability in a synthetic wine after the preservation processes. No significant differences in the cultivability, with respect to the controls cells, were observed after freezing at -80 °C and -20 °C, and pre-acclimated cells were more resistant to freeze-drying than non-acclimated ones. The results of multiparametric flow cytometry showed a significant level of membrane damage after freeze-drying in two of the three strains. The cultivability was determined after incubation in wine-like medium containing 13 or 14% v/v ethanol at 21 °C for 24 h and the results were interpreted using principal component analysis (PCA). Acclimation was the most important factor for preservation, increasing the bacterial resistance to ethanol after freezing and freeze-drying. Freeze-drying was the most drastic method of preservation, followed by freezing at -20 °C. The increase of ethanol concentration from 6 to 10% v/v in the acclimation medium improved the recovery of two of the three strains. In turn, the increase of ethanol content in the synthetic wine led to a dramatic decrease of viable cells in the three strains investigated. The results of this study indicate that a successful inoculation of dehydrated L. plantarum in wine depends not only on the use of protective agents, but also on the cell acclimation process prior to preservation, and on the ethanol content of wine.
(Copyright © 2015 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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