Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
For full article and contact information, see Angew. Chem. Int. Ed. 2000, 39 (15), 2766 - 2768
Sourdough as Subject of Research
isolated from lactic acid bacteria
One the one hand, we like to indulge our vices, such as smoking or eating potato chips; on the other hand, consumers today are placing increased value on "healthy" foods. For example, yogurts containing live, active cultures have become fashionable in recent years. These contain special lactic acid-producing bacteria that are supposed to improve the state of intestinal bacteria, improving general health as well. Whether this is actually true has always been called into question by critics.
This discussion could now be revived by a discovery made by scientists working with chemist Günther Jung in Tübingen: they have been the first to isolate and characterize a low-molecular antibiotic from a strain of lactic acid-producing bacteria.
Lactic acid bacteria have long been used to make various dairy products, sauerkraut or also sourdough for bread. In a sourdough that is used in the production of a commercial baking product, the strain Lactobacillus reuteri came to the attention of the researchers. Lactobacillus reuteri is also among the naturally occurring intestinal bacteria in humans and animals. Microbiologists of the University Hohenheim found an inhibiting agent in cell samples and culture supernatant of this bacterium, Jung and his coworkers resolved its structure. The previously unknown antibiotic was appropriately named reutericyclin, after its source. In sourdough, lactobacillus reuteri is in a position to use this substance to control the growth of a whole series of undesirable bacterial strains, or even to kill them off entirely. Its structure puts reutericyclin in the category of tetramic acid. Many other tetramic acids with a broad spectrum of biological activity have previously been found in nature.
It has been shown previously that antibiotic substances from lactobacillus protect against infections of salmonella and helicobacter - which was recently exposed as a cause of stomach ulcers. However, none of these substances have been chemically characterized, until now.
"The discovery of reutericyclin provides totally new points of discussion about the use of lactic acid-producing bacteria in the preservation of foods and in influencing human intestinal bacteria," Jung is convinced of. At present, larger amounts of the new antibiotic are being produced by EMC microcollections GmbH in Tübingen.