Antioxidant and antibacterial activities of exopolysaccharides produced by lactic acid bacteria isolated from yogurt

Abstract

The objectives of this study were to optimize the conditions for cell growth and exopolysaccharides (EPS) production by using pure and mixed microbial cultures of Streptococcus thermophilus and Lactobacillus bulgaricus, and to evaluate the antioxidant and antibacterial activities of EPS in vitro. The mixed cultures of two strains showed a higher cell growth whereas the higher EPS production was detected in pure culture with S. thermophilus. The optimal medium were determined as follows (g/l): sucrose 50, yeast extract 10, KH2PO4 3 , MgSO4.7H2O 0.05 and pH initial 6.5 at 30°C. Under the optimized conditions, the values of dry cell weight (DCW) and EPS were 5.2± 0.8 g/l and 56.8 ± 0.62 mg/ml, respectively. The EPS demonstrated a positive antioxidant potential on DDPH radical scavenging. The agar diffusion assay showed that purified EPS exhibited antibacterial activities against tested pathogens such as Escherichia coli ATCC 250922 and Staphyloccocus aureus ATCC 250923 at (62-1000) μg/mL. In conclusion, EPS have an antioxidant activity and could have applications in the food industry.

Value of Molecular Genetic Markers in the Prognosis of Locally Advanced Forms of Cervical Cancer

“…Excessive production of free radicals leads to oxidative damage to biomolecules (lipids, proteins, DNA), resulting in many chronic diseases, such as atherosclerosis, cancer, diabetes, rheumatoid arthritis, post-ischemic perfusion injury, myocardial infarction, cardiovascular diseases, chronic inflammation of organs, stroke and septic shock, aging and other diseases [26]. In Zouaoui Benattouche et al notes shows that when studying the activity of EPS from S. thermophilus, the highest antioxidant activity of 55.83% was observed with the concentration of PES 1000 g/ml [27]. Although the EPS from L. plantarum YW32 comparatively low results were obtained than with ascorbic acid, but at a dose of 5 mg/ml, EPS shows promising antioxidant activity with 30% absorption of DPPH radicals [23].…”

A multi-functional survey of the properties of Lacticaseibacillus paracasei subsp. tolerans NOC-122, Levilactobacillus parabrevis NOC-111 and Latilactobacillus curvatus NOC-110

“…For example, some strains of Lactobacillus kefiranofaciens, Limosilactobacillus reuteri and Limosilactobacillus frumenti produce EPS in kefir and/or sourdough microflora. Also, EPS are known to improve textural, rheological and organoleptic properties of foods, with positive health-related properties such as prebiotic, antimicrobial and antioxidant activities [13].…”