Rapid detection assay for oxygen consumption in the Lactobacillus casei group

A rapid method based on the time of resazurin reduction was optimized and use to evaluate the oxygen consumption in Lactobacillus casei, L. paracasei and L. rhamnosus strains grown under anaerobic, aerobic and respiratory promoting conditions. A good correlation was found between the resazurin assay and polarographic measurements. The new method proved to be a faithful indicator of oxygen uptake as well as fast and effective for testing a large number of strains. Additionally, being correlated to other markers of aerobic and respiratory phenotypes (improved growth and activity of enzymes related to oxygen metabolism), the resazurin assay may greatly facilitate the screening of lactic acid bacteria for the ability to use oxygen under different growth conditions and the selection of potentially respiration-competent strains.