Antioxidative properties of Lactobacillus sake upon exposure to elevated oxygen concentrations

The ability of bacteria to overcome oxidative stress is related to the leve ls and types of antioxidative mechanisms which they possess. In this study, the antioxidative properties in Lactobacillus sake strains from different food origins were determined at low temperature (8 degreesC) and upon expos ure to oxygen levels between 20 and 90% O-2. The L sake strains tested grew well at 8 degreesC and in the presence of 20% O-2, however, most of the st rains could not grow at O-2 levels as high as 50 and/or 90%. Cell-free extr acts of all strains possessed certain levels of hydroxyl radical scavenging , metal chelating and reducing capacities essential for growth of cells at ambient O-2. At elevated O-2 concentrations, a high H2O2 splitting capacity and low specific rates of H2O2 production were demonstrated in the O-2-ins ensitive strain L. sake NCFB 2813, which could grow at elevated O-2 Conditi ons. Although H2O2 was generated in the O-2-sensitive L. sake DSM 6333 at l evels which were not directly toxic to the cells (<0.2 mM), we can conclude that its removal is essential for cell protection at elevated O-2 conditio ns. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.