Sodium acetate enhances hydrogen peroxide production in Weissella cibaria

Aims: To investigate hydrogen peroxide production by lactic acid bacteria (LAB) and to determine the key factors involved. Methods and Results: Six strains of Weissella cibaria produced large amounts (2.2-3.2 mmol l(-1)) of hydrogen peroxide in GYP broth supplemented with sodium acetate, but very low accumulations in glucose yeast peptone broth without sodium acetate. Increased production of hydrogen peroxide was also recorded when strains of W. cibaria were cultured in the presence of potassium acetate, sodium isocitrate and sodium citrate. Oxidases and peroxidases were not detected, or were present at low levels in W. cibaria. However, strong nicotinamide adenine dinucleotide (NADH) oxidase activity was recorded, suggesting that the enzyme plays a key role in production of hydrogen peroxide by W. cibaria. Conclusions: Weissella cibaria produces large quantities of hydrogen peroxide in aerated cultures, in a process that is dependent on the presence of acetate in the culture medium. NADH oxidase is likely the key enzyme in this process. Significance and Impact of the Study: This is the first study showing that sodium acetate, normally present in culture media of LAB, is a key factor for hydrogen peroxide production by W. cibaria. The exact mechanisms involved are not known.