Bacterial Polysaccharides: An Overview

Abstract

Bacterial cell wall and membrane are associated with a variety of glycoconjugates and polysaccharides which aids in structural formation as well as performing various functions in the bacterial cell. In gram-negative bacteria, peptidoglycan is majorly present in the periplasmic space and it provides mechanical strength as well as shape to the cell. In some cases, the periplasm contains membrane-derived oligosaccharides (MDOs), which are involved in osmoregulation. The outer membrane mainly contains lipopolysaccharides (LPSs) that bind to divalent cations or chelators for structure stabilization and to increase outer membrane permeability. This LPS contains lipid A, also known as endotoxin, which has shown a powerful biological effect in mammals such as fever, septic shock, multiple organ failure, and mortality. The mucoid (slime-producing) strains contain capsular polysaccharide which aids as virulence factor. The gram-positive bacteria lack an outer membrane and have a much thicker peptidoglycan layer along with a specialized polysaccharide known as teichoic acid. It provides cell wall integrity through complex formation with cations and also assists in cell growth regulation. The present report attempts to provide an overview of bacterial polysaccharide structure, occurrence, and their important functions, along with the biosynthesis and major inhibitors to block biosynthetic pathways.