Osmoprotectants and cryoprotectants for Listeria monocytogenes

Listeria monocytogenes is a foodborne pathogen that can grow in high osmoti c strength environments and at refrigeration temperatures. Glycine betaine, proline betaine, acetylcarnitine, carnitine, gamma-butyrobetaine and 3-dim ethylsulphoniopropionate all acted as osmoprotectants, as evidenced by an i ncrease in growth rate of L. monocytogenes 10403S and Scott A when provided with these compounds, while being stressed in defined medium containing 0. 7 M NaCl. These same compounds exhibited cryoprotective activity, as eviden ced by increasing the growth rate of L. monocytogenes at 5 degrees C. Ectoi ne, hydroxy ectoine, pipecolic acid and proline were ineffective as osmopro tectants or cryoprotectants under these conditions. The presence of osmopro tectants and cryoprotectants in foods map provide compounds assisting L. mo nocytogenes to overcome the barriers of high osmotic strength and low tempe rature that otherwise control microbial growth.