Bacterial Alginate Biosynthesis and Metabolism

Abstract

Alginate is a linear anionic heteropolysaccharide with a chemical structure consisting of 1,4-linked subunits of β-D-mannuronic acid (M) and its C-5 epimer α-L-guluronic acid (G). It is well known that the monomer composition and molecular weight of alginates affect their properties and influence their use in the food and pharmaceutical industries. Alginate is usually extracted from seaweed for commercial purposes, but can also be produced by bacteria as exopolysaccharide (EPS). Pseudomonas spp. and Azotobacter vinelandii are well-known alginate-producing microorganisms. Their biochemical machinery for alginate biosynthesis is influenced by changing culture conditions and manipulating genes/proteins, making it relatively easy to obtain customized EPS with different molecular weights, M/G compositions, and thus physicochemical properties. Although these two genera have very similar biosynthetic pathways and molecular mechanisms for alginate production, with most of the genes involved being virtually identical, their regulation has been shown to be somewhat different. In this chapter, we present the main steps of alginate biosynthesis in bacteria, including precursor synthesis, polymerization, periplasmic modifications, transport/secretion, and post-secretion modification.

Carbon source and surface type influence the early-stage biofilm formation by rhizosphere bacteriumPseudomonas donghuensisP482

“…The polysaccharide biosynthesis involves multiple energy-requiring processes and regulation (Flemming and Wingender, 2010;Flemming et al, 2023), when various carbohydrates (mannose, glucose, rhamnose, mannuronic acid, etc.) are incorporated into the polymeric chains (Ma et al, 2006;Vassoler Serrato, 2022) formation for all strains lacking the inactivated enzymes associated with matrix compounds biosynthesis in the presence of glycerol and citrate, when compared to wild-type, but the inability to develop biofilm structures was observed for all three carbon sources. It has been shown for P. aeruginosa that mutations in genes involved in the synthesis of exopolysaccharide alginate or LPS affect also the twitching motility (Whitchurch et al, 1996;Abeyrathne et al, 2005), impacting bacterial attachment to surfaces.…”