Compatible solutes – the mycological dimension and their role as physiological buffering agents

Abstract

Glycerol, mannitol and proline, compatible solutes produced by fungi in response to salt or water stress, can be involved in futile or substrate cycles. It is argued, on the basis of chemostat cultures with both bacteria and fungi, that substrate cycles which dissipate energy are necessary processes when fungi are subjected to osmotic or water stress. Whether or not the three compounds are also involved in overflow metabolism remains to be established. It is argued that substrate cycles may have more general importance when a fungus is growing under types of stress other than that caused by high concentrations of salt or low availability of water. The arguments put forward strengthen the case for considering the three compounds as part of a general class of physiological buffering agents. A modified version of the mannitol cycle is proposed. Copyright © 1990, Wiley Blackwell. All rights reserved