A genomic approach to enhance the selection of lactic acid bacteria producing exopolysaccharides

Lactic acid bacteria (LAB) are widely used in fermented foods for their functional, preservative, and aroma-forming properties. In dairy products, LAB can modulate texture through exopolysaccharides (EPS) biosynthesis, but not all EPS can improve texture and sensory attributes. Finding EPS producing strains using traditional laboratory screening (e.g., visual observation, chemical quantification) is laborious. In this study, a k-mer-based genomic strategy was used to rapidly identify and cluster LAB with genetic potential to synthesize homopolysaccharides (HoPS) and heteropolysaccharides (HePS). Using curated databases of EPS-related genes, 537 draft genomes from seven LAB genera were screened, revealing 236 HoPS- and 294 HePS-potential strains clustered into 62 and 49 groups, respectively. The approach eliminated all strains devoid EPS loci and was a good indication of the presence of EPS-related genes. HoPS and HePS cluster representatives were phenotyped on sucrose-supplemented agar, revealing 11.8% ropy strains, thereby accelerating the discovery of texturing cultures for dairy applications.