Antioxidative ability of lactic acid bacteria

Area of Science:

• Microbiology
• Biochemistry
• Food Science

Background:

• Lactic acid bacteria (LAB) are known for their health benefits, including potential antioxidant properties.
• Understanding the specific antioxidant mechanisms of different LAB strains is crucial for their application in functional foods and nutraceuticals.

Purpose of the Study:

• To investigate the antioxidative activity of 19 different strains of lactic acid bacteria.
• To elucidate the underlying antioxidative mechanisms, including metal ion chelation, reactive oxygen species (ROS) scavenging, enzyme inhibition, and reducing activity.

Main Methods:

• Preparation of intracellular cell-free extracts from 19 LAB strains (Lactobacillus acidophilus, Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium longum).
• Assay of antioxidant activities: ascorbate autoxidation inhibition, metal ion chelating ability (Fe2+, Cu2+), ROS scavenging (hydroxyl radical, hydrogen peroxide), reducing activity, and enzyme inhibition (superoxide dismutase).

Main Results:

• All tested LAB strains exhibited antioxidative activity, inhibiting ascorbate autoxidation by 7-12%.
• Streptococcus thermophilus 821 showed the highest Fe2+ chelating ability, while Bifidobacterium longum 15 708 demonstrated the highest Cu2+ chelating ability.
• All strains scavenged ROS; Lactobacillus acidophilus E excelled in hydroxyl radical scavenging, and Bifidobacterium longum B6 showed the best hydrogen peroxide scavenging.
• All strains possessed reducing activity, with Bifidobacterium longum B6 exhibiting the highest reducing power.
• No superoxide dismutase activity was detected in any strain, nor was it induced by metal ions.

Conclusions:

• The intracellular cell-free extracts of all 19 lactic acid bacteria strains possess significant antioxidative properties through multiple mechanisms.
• Specific strains, such as Bifidobacterium longum B6 and Streptococcus thermophilus 821, show superior capabilities in certain antioxidant activities, highlighting their potential for targeted applications.
• The absence of superoxide dismutase activity suggests that the primary antioxidant defense in these LAB strains relies on other mechanisms like metal chelation and ROS scavenging.