# Extracellular Polymeric Substances Produced by Actinomycetes of the Genus Rhodococcus for Biomedical and Environmental Applications

## TL;DR

This review explores the diverse extracellular polymeric substances (EPSs) from Rhodococcus bacteria and their potential in biomedicine, bioremediation, and other industries.

## Contribution

The paper provides a comprehensive overview of the biochemical and functional diversity of Rhodococcus EPSs and highlights their underexplored potential.

## Key findings

- Rhodococcus EPSs have varied structures and properties, including emulsifying and flocculating abilities useful in bioremediation.
- EPSs show antiviral, anti-inflammatory, and antibiofilm activities, making them valuable for biomedical and food applications.
- Molecular regulation and biosynthetic pathways of Rhodococcus EPSs remain poorly understood, limiting their full exploitation.

## Abstract

Extracellular polymeric substances (EPSs) produced by actinomycetes of the genus Rhodococcus play crucial roles in their ecological success, metabolic versatility, and biotechnological value. This review summarizes existing studies of Rhodococcus EPSs, emphasizing the biochemical composition, functional attributes, and practical significance of EPSs, as well as their importance in biomedicine, bioremediation, and other applications (food industry, biomineralization) with respect to the EPS chemical composition and biological roles. Rhodococcus species synthesize complex EPSs composed primarily of polysaccharides, proteins and lipids that, like in other bacteria, support cell adhesion, aggregation, biofilm formation, and horizontal gene transfer (and can prevent exogenous DNA binding) and are highly important for resistance against toxicants and dissolution/assimilation of hydrophobic compounds. EPSs produced by different species of Rhodococcus exhibit diverse structures (soluble EPSs, loosely bound and tightly bound fractions, capsules, linear and branched chains, amorphous coils, rigid helices, mushroom-like structures, extracellular matrix, and a fibrillar structure with a sheet-like texture), leading to variations in their properties (rheological features, viscosity, flocculation, sorption abilities, compression, DNA binding, and interaction with hydrophobic substrates). Notably, the EPSs exhibit marked emulsifying and flocculating properties, contributing to their recognized role in bioremediation. Furthermore, EPSs possess antiviral, antibiofilm, anti-inflammatory, and anti-proliferating activities and high viscosity, which are valuable in terms of biomedical and food applications. Despite extensive industrial and environmental interest, the molecular regulation, biosynthetic pathways, and structural diversity of Rhodococcus EPSs remain insufficiently characterized. Advancing our understanding of these biopolymers could expand new applications in biomedicine, bioremediation, and biotechnology.