The author has completed the ICMJE form and declares no conflicts of interest. The picture shows tubes with brown and normal-coloured serum. The brown sample was taken from a man in his thirties who ...

Two lactic acid bacteria, Lactobacillus fermentum and Lactobacillus rhamnosus, and Saccharomyces cerevisiae, all of which are widely used in fermentation and preservation of food, were assayed on ...