Osmotic Response of Lactic Bacteria grown at different water activities

TYMCZYSZYN E.; BAEZ D.; DISALVO A.

Bariloche - Argentina

Congreso; XIII Reunión Anual de la Sociedad Argentina de Biofísica; 2003

The preservation of lactic bacteria for biotechnological purposes by freezing or desiccation, produces a severe dehydration o0f the cells causing irreversible damages at membrane level. The damage affect the water and ionic permeability. As rehydration involves a reincorporation of water to the cell, increasing their volume, the permeability properties of the membrane can be measure by means of the osmotic response of the bacteria. In this work we have measure the osmotic response of bacteria grown in different water activities and correlated its response with the changes in the lipid composition and the probable presence of specific transport molecules. The water permeability measured by changes in light scattering was determined in a stopped-flow spectrometry. The results indicate that bacteria grown at low water activities are less permeable to water due to the increase in saturated fatty acids. In addition, it was observed that part of the water flux may be taking place though specific transport systems that are inhibit by HgCl2