Hypocholesterolemic, antidiabetic and bioactive properties of ultrasound-stimulated exopolysaccharide produced by Lactiplantibacillus plantarum strains

Abstract

This study aimed to investigate the effects of ultrasound (US) pretreatment (100 W, 30 kHz; 0%, 25%, 50%, and 75% amplitudes, 15 min) on exopolysaccharide (EPS) production efficiency of L. plantarum LS5 and LU5 strains. Physicochemical (molecular weight and sugar composition) and bioactive properties of extracted EPSs such as antibiofilm, α-amylase inhibition, cholesterol-lowering, and antioxidant activities were investigated. The EPS production yield of strains was growth-associated and LS5 had more efficiency than LU5 but their molecular weights did not differ, significantly (p > 0.05). The predicted results were mathematically confirmed experimental data. The α and β values (EPS production constant) were obtained by the Elovich model (EM) using a genetic algorithm indicated that the highest EPS production was found for LS5 and an amplitude of 50%. Extracted EPSs were heteropolysaccharides and showed dose-dependent antioxidant properties. DPPH scavenging activity of LS5-EPS was higher than LU5-EPS but their Fe3+ reducing power did not differ markedly (p > 0.05). They had the highest and lowest antibiofilm activity against S.aureus and E. coli, respectively. The maximum α-amylase inhibition (35.13%) and Cholesterol-lowering activities (42.56%) were achieved by LU5-EPS and LS5-EPS, respectively. As a result, LS5-EPS was more bioactive than LU5-EPS, and ultrasound pretreatment at 50% amplitude is an efficient way for increasing LS5-EPS production, which has a great potential in the production of functional food and employment in pharmaceutical industries.