Bioactive exopolysaccharide from Limosilactobacillus fermentum LAB-1: Antioxidant, anti-inflammatory, antibacterial and antibiofilm properties

Exopolysaccharides (EPS) are an intriguing group of high-molecular-weight carbohydrate polymers known for their diverse functional benefits. Our study focused on assessing the bioactive characteristics of EPS produced by Limosilactobacillus fermentum LAB1, lactic acid bacterium (LAB) isolated from the popular dairy beverage Borhani. Previous research had demonstrated its robust antimicrobial potential against various pathogens and provided genomic evidence of its EPS production. In this investigation, we verified and validated the EPS production ability of LAB1 through a battery of tests including the string test, Congo red agar test, and aniline blue agar plate method, all of which produced positive results. The EPS extracted from LAB1 displayed a high carbohydrate-to-protein ratio and exhibited a multifaceted repertoire of bioactive properties. It demonstrated antimicrobial activity against both Gram-positive and Gram-negative pathogens, and showed the ability to inhibit biofilm formation in Staphylococcus aureus (76.61%) and Escherichia coli (13.64%). Furthermore, the EPS exhibited DPPH free radical scavenging (92.25%), hydroxyl radical scavenging (87.82%), and reducing power capacity (3.1 mM/L), which indicate its substantial antioxidant potential. Additionally, the EPS sample demonstrated significant anti-inflammatory activity (75.79 %) and moderate oil emulsifying capacity with an emulsification index of 38.38%. These findings underscore the versatility of LAB1 EPS, positioning it for diverse applications and highlighting its multifunctional role across various industrial domains.