ROLE OF GLYCINE BETAINE AND RELATED OSMOLYTES IN OSMOTIC-STRESS ADAPTATION IN YERSINIA-ENTEROCOLITICA ATCC-9610

Yersinia enterocolitica is a gram-negative, food-borne pathogen that c an grow in 5% NaCl and at refrigerator temperatures, In this report, t he compatible solutes (osmolytes) which accumulate intracellularly and confer the observed osmotic tolerance to this pathogen were identifie d. In minimal medium, glutamate was the only detectable osmolyte that accumulated in osmotically stressed cells, However, when the growth me dium was supplemented with glycine betaine, dimethylglycine, or carnit ine, the respective osmolyte accumulated intracellularly to high level s and the growth rates of the osmotically stressed cultures improved f rom 2.4- to 3.5-fold, Chill stress also stimulated the intracellular a ccumulation of glycine betaine, but the growth rate was only slightly improved by this osmolyte, Both osmotic upshock and temperature downsh ock stimulated the rate of uptake of [C-14]glycine betaine by more tha n 30-fold, consistent with other data indicating that the osmolytes ar e accumulated from the growth medium via transport.