Do Periplasmic Oligosaccharides Provide a Role in the Osmotic Adaptation of Gram-Negative Bacteria?

Abstract

A wide diversity of Gram-negative bacteria has been shown to strictly osmoregulate the biosynthesis of anionic periplasmic oligosaccharides. Specifically, the concentrations of these oligosaccharides and their counterions increase when cells are grown in media of low osmolarity. Based on the amounts of these oligosaccharides, their presence should substantially influence periplasmic osmotic strength and volume. In addition, the development of a Donnan potential across the outer membrane of Gram-negative bacteria should also derive largely from the concentrations of these anionic periplasmic oligosaccharides. This paper provides a review of several studies which indicate that the cell-envelope structure of Gram-negative bacteria is influenced greatly by the presence of periplasmic oligosaccharides. The possible role for these compounds in the osmotic adaptation of Gram-negative bacteria is also considered.