[Microorganisms in our food: yesterday, today and tomorrow]

The development of fermented foodstuffs can be considered as one of the greatest achievements of human civilization and goes back thousands of years. It arose from the necessity to conserve foods, to make them more digestible and also more enjoyable. During the centuries man learned by trial and error to conduct the fermentation processes by changing physical and chemical parameters in the basic food ingredients. It took much longer, however, to discover the cause of fermentation processes: only towards the end of the 19th century it was demonstrated, for example, that baker's yeast is the cause of alcoholic fermentation. Through the development of the technique of "pure microbial culture", developed again with yeast, the basis for a controlled use of microbes in food industry was established. The movement from artisan to industrial scale fermentations made necessary a systematic strain development by the "classical" techniques of "mutation, selection and recombination". The modern techniques of genetic engineering have hardly been applied to food microorganisms so far. These methods, which usually have been developed with laboratory strains, would give us the possibility to change or disrupt genes very specifically and even to introduce new genes into established food microorganisms. Some possible applications with the baker's yeast are discussed in this article.