# Tea-Residue-Derived Klebsiella pneumoniae CGMCC 31459: Genomic Insights and Antioxidant Activity of Its Exopolysaccharides

## TL;DR

This study explores a non-hypervirulent strain of Klebsiella pneumoniae and its exopolysaccharides, which show antioxidant and anti-aging properties.

## Contribution

The study provides genomic and biochemical insights into a non-hypervirulent Klebsiella pneumoniae strain and its functional exopolysaccharides.

## Key findings

- The genome of Klebsiella pneumoniae CGMCC 31459 lacks hypervirulence loci and has genes related to EPS biosynthesis.
- EPS-KP is a branched heteropolysaccharide with significant antioxidant activity and anti-aging effects in C. elegans.

## Abstract

Exopolysaccharides (EPSs) are important extracellular metabolites secreted by microorganisms. Klebsiella pneumoniae is an opportunistic pathogen widely distributed in the environment, host mucosal and intestinal surfaces, and EPS from Klebsiella pneumoniae are of significant interest. Conventional studies have mainly focused on hypervirulent strains, whereas comprehensive investigations of non-hypervirulent strains and their EPS functionalities remain limited. This study employed ST678-type Klebsiella pneumoniae CGMCC 31459 as the model to investigate genomic characteristics, EPS structural features, and biological activities. Its genome comprises one chromosome and four plasmids, functionally enriched in carbohydrate metabolism genes, including abundant glycoside hydrolases and glycosyltransferases essential for EPS biosynthesis. Virulence and antimicrobial resistance assessments confirmed the absence of typical hypervirulence loci, indicating genetic stability with low pathogenic and resistance potential. EPS-KP is a weakly acidic, branched heteropolysaccharide composed of glucose, galactose, mannose, and glucuronic acid. EPS-KP exhibited significant antioxidant and anti-aging activities, with a 77.47% (5 mg/mL) superoxide anion scavenging rate and a 30.9% (200 μg/mL) lifespan extension in Caenorhabditis elegans, accompanied by enhanced SOD/CAT enzyme activity and reduced lipofuscin accumulation. This integrated genomic and biochemical analysis provides new insights into the safe, non-hypervirulent Klebsiella pneumoniae strain and its functional EPS, highlighting its potential for biotechnological applications.