Analysis of the effects of osmoprotectants on the high osmolality-dependent induction of increased thermotolerance in Salmonella typhimurium

Challenge of Salmonella typhimurium with high osmolality enhances ifs therm otolerance, manifested as faster growth rate at non-lethal high temperature s and enhanced resistance to killing at lethal high temperatures. Previousl y, it has been shown that She potent osmoprotectant glycine betaine blocks the latter response, in this work, we tested the effects of ten other osmop rotectants on She induction of thermotolerance by high osmolality. The high osmolality-dependent growth stimulation at 45 degreesC was decreased parti ally by gamma -aminobutyrate betaine, 3,4-dehydroproline betaine, and block ed completely by pipecolate betaine and homarine. Osmotic enhancement of su rvival at 53 degreesC was greatly impaired by dehydroproline betaine, pipec olate betaine, and proline betaine. Our observations point to the need for further research to discover additional betaine analogs, which might act as even more potent antagonists of the induction of thermotolerance, for poss ible use in food products to enhance the susceptibility of Salmonella to th ermal injury or killing (C) 2001 Academic Press.