CHARACTERIZATION OF PROBIOTIC LACTIC ACID BACTERIA WITH ANTIOXIDANT POTENTIAL IN VITRO AND IN VIVO AND THEIR APPLICATION IN PROBIOTIC PRODUCTS

Abstract

The aims of this study are (1) to investigate the antioxidative activities of lactic acid bacteria (LAB), isolated from healthy infant feces; and (2) to develop a probiotic yoghurt with antioxidative activities. The viable cells, cell-free supernatant and intracellular cell-free extract of MSMC36-9, MSMC37-3, MSMC37-4, and MSMC83 at a concentration of 1×109 CFU/mL exhibited antioxidant activities including 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging capacity, hydroxyl radical scavenging capacity and an intracellular free radical level on Caco-2 cells. The evaluation of the probiotic properties of four LAB isolates showed a high survival rate in gastrointestinal conditions, and a substantial adherence to Caco-2 cells. MSMC36-9, MSMC37-3, MSMC37-4 were assigned to Lactobacillus paracasei while MSCM83 was assigned to Bifidobacterium animalis based on their 16S rRNA sequence analysis and physiological properties. Among the four LAB isolates, B. animalis MSMC83 was the strong antioxidant activity and the highest potential for probiotic properties. Therefore, B. animalis MSMC83 was selected to be analyzed for antioxidant activity in oxidative stress rats induced by D-galactose. The results showed that B. animalis MSMC83 significantly reduced fasting blood glucose, total cholesterol, and triglyceride. Interestingly, the administration of B. animalis MSMC83 significantly increased the antioxidant enzymes, consisting of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH‐Px) in serum, while the content of malondialdehyde (MDA) decreased. Moreover, liver tumour necrosis factor-alpha (TNF-alpha) significantly decreased in probiotic groups when compared with the D-galactose model group. The analysis of gut microbiota revealed that B. animalis MSMC83 could recover the microbiota diversity after induced D-galactose. Further, B. animalis MSMC83 was selected to use in the production of probiotic yoghurt. The fermentation of B. animalis MSMC83 in combination with Streptococcus thermophilus and Lactobacillus bulgaricus at the ratio of 1:1:1 in milk for the development of yoghurt was performed, and the microbiological and physicochemical properties of yoghurt were investigated while in refrigerated storage. The results showed that fermentation time for yoghurt with added B. animalis MSMC83 was significantly shortened. The viable cell counts remained stable throughout the storage period. B. animalis MSMC83 could be used as probiotic culture in the development of functional foods for preventing and controlling the diseases associated with oxidative stress.

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