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498 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYeffects against E. coli ATCC 10536 and B. cereus ATCC 11778. L. plantarum R315 was found to possess antibacterial activity against Listeria monocytogenes CMCC54007, S. aureus CGMCC26003, S. typhimurium ATCC13311, and Bacillus cereus ATCC14579 at 0.6 mg/mL [5]. Antibacterial property of EPS could be attributed to the presence of sugar subunits and functional groups being carbonyl, phosphate, and hydroxyl groups Therefore, antibacterial activity against pathogens varies despite being classified into same species. Many studies have hypothesized that EPSs disrupt the bacterial cell wall peptidoglycan layer and interfere with receptors and channels on the surface of Gram-negative bacterial cells, and result in secondary metabolites accumulation in the liquid medium [20]. Although various studies showed antibacterial activity of EPS from LAB, the underlying mechanisms remain unknown [7].Oxidative stress is known as redox imbalance between reactive oxygen species and antioxidant agents inside the cells [1]. There has been abundant evidence suggesting that ROS is involved in various disorders and diseases such as cancer, Parkinson%u2019s disease, Alzheimer%u2019s disease, atherosclerosis, and inflammation [22]. EPSs have been considered to be natural antioxidants holding potential applications in food, pharmaceutical, and cosmetic industries [7; 17]. In the current study, L. plantarum MT12 produced EPS that exhibited strong antioxidant activity against DPPH and hydroxyl radicals at 1.2 mg/mL. It was consistent to the previous study indicating 5 mg/mL EPS from L. plantarum Z-1 had DPPH and hydroxyl radical scavenging activities of 88.6% and 63.6%, respectively [17]. However, it was 4.1-fold lower than that of MT12. Monosaccharide compositions, structural characteristics, and binding positions are supposed to be primary factors contributing to the antioxidant activity of EPS [2]. Taken together, the EPS from MT12 could be a promising candidate for the