Taxonomic, biochemical, and genome-guided characterization of Halomonas elongata N1T reveals its potential as a sustainable microbial cell factory for human lectin-binding exopolysaccharide production

Microbial exopolysaccharides (EPSs) have attracted considerable attention as sustainable biopolymers for applications in the food, pharmaceutical, cosmetic and environmental sectors. Halophilic bacteria of the genus Halomonas are emerging as attractive industrial production hosts because their ability to grow under saline conditions reduces contamination risks and may enable cost-effective, low-sterility bioprocesses. However, relatively few EPS-producing Halomonas strains have been comprehensively characterized by integrating physiological, genomic and structural analyses. In this study, an EPS-producing halophilic bacterium, designated Halomonas elongata N1T, was isolated from the hypersaline Salt Lake of Yerevan, Armenia, and evaluated as a potential microbial cell factory for sustainable EPS production. Phylogenomic analyses confirmed its affiliation with H. elongata , showing 98.9% average nucleotide identity and 90.9% digital DNA–DNA hybridization with the type strain DSM 2581 T . Genome analysis identified multiple carbohydrate-active enzymes together with three major polysaccharide biosynthetic gene clusters containing canonical ABC transporter-dependent export proteins and numerous glycosyltransferases, providing a genetic basis for EPS biosynthesis. Cultivation under buffered saline conditions markedly enhanced polymer production, yielding up to 517 mg L −1 crude exoproduct, while inexpensive sugarcane molasses supported comparable production levels to sucrose, demonstrating the feasibility of using an agro-industrial by-product as a carbon source. Chemical characterization revealed a high-molecular-weight (approximately 250–500 kDa) heteropolysaccharide composed primarily of rhamnose, glucosamine, glucose and ribose, and preliminary NMR analysis confirmed its structural heterogeneity. In addition, the purified EPS exhibited a binding to the human C-type lectins Langerin and DC-SIGN, suggesting potential biological functionality beyond conventional industrial applications. The integration of physiological characterization, comparative genomics, EPS biosynthetic pathway analysis and polymer characterization demonstrates that H. elongata N1T is a promising candidate for sustainable EPS production. Its ability to efficiently synthesize EPS under saline conditions while utilizing an inexpensive renewable substrate highlights its potential as a microbial cell factory for future industrial bioprocesses. The unique genomic features and lectin-binding properties of the polymer further broaden its prospective applications in biotechnology and biomedicine.