Xanthan: enzymatic degradation and novel perspectives of applications

Abstract

The extracellular heteropolysaccharide xanthan, synthesized by bacteria of the genus Xanthomonas, is widely used as a thickening and stabilizing agent across the food, cosmetic, and pharmaceutical sectors. Expanding the scope of its application, current efforts target the use of xanthan to develop innovative functional materials and products, such as edible films, eco-friendly oil surfactants, and biocompatible composites for tissue engineering. Xanthan-derived oligosaccharides are useful as nutritional supplements and plant defense elicitors. Development and processing of such new functional materials and products often necessitate tuning of xanthan properties through targeted structural modification. This task can be effectively carried out with the help of xanthan-specific enzymes. However, the complex molecular structure and intricate conformational behavior of xanthan create problems with its enzymatic hydrolysis or modification. This review summarizes and analyzes data concerning xanthan-degrading enzymes originating from microorganisms and microbial consortia, with a particular focus on the dependence of enzymatic activity on the structure and conformation of xanthan. Through a comparative study of xanthan-degrading pathways found within various bacterial classes, different microbial enzyme systems for xanthan utilization have been identified. The characterization of these new enzymes opens new perspectives for modifying xanthan structure and developing innovative xanthan-based applications. Key points • The structure and conformation of xanthan affect enzymatic degradation. • Microorganisms use diverse multienzyme systems for xanthan degradation. • Xanthan-specific enzymes can be used to develop xanthan variants for novel applications.

Identification of a novel xanthan-binding module of a multi-modular Cohnella sp. xanthanase

“…Xanthan is a natural bacterial polysaccharide secreted by Xanthomonas species such as the plant pathogenic Xanthomonas campestris ( Rogovin et al, 1961 ; Petri, 2015 ). It has a β-1,4-linked glucan backbone with mannosyl-glucuronosyl-mannosyl side chains attached to the C-3 position of every second glucose residue ( Jansson et al, 1975 ; Berezina et al, 2024 ). Depending on the production conditions, the inner mannosyl residues of the side chains are often acetylated while the terminal mannosyl residues are pyruvylated ( Tait et al, 1986 ; García-Ochoa et al, 2000 ).…”

“…Typically, xanthan degradation and utilization by bacteria involves extracellular xanthan lyase, which cleaves off the terminal, usually pyruvylated mannosyl residues of the side chains, and an extracellular backbone-cleaving xanthanase, as well as intracellular enzymes for deacetylation and breakdown of internalized xanthanderived oligosaccharides (Hashimoto et al, 1998(Hashimoto et al, , 1999Nankai et al, 1999Nankai et al, , 2002. The bacterial extracellular enzymes involved in the initial steps of xanthan breakdown can also be used for xanthan modification and for the production of xanthan oligosaccharides (Berezina et al, 2024). Enzymatic side chain modification of xanthan can be accomplished by xanthan lyases (Hashimoto et al, 2003;Yang et al, 2014).…”