Strategies for microbial growth at reduced water activities.

Microorganisms that are capable of growth at reduced water activities all rely on a common strategy for survival, i.e. the intracellular accumulation of a solute or solutes to balance the external water activity (aw), thus preventing the mass movement of water out of the cell. Understanding the physiological mechanisms that enable solutes to be accumulated and retained against strong concentration gradients, and the genetic controls on these processes may, in future, lead to the genetic manipulation of crop plants to increase their drought resistance.