Genome of the yoghurt bacterium deciphered
The genome of the lactic acid bacterium to which we owe the yoghurt has been deciphered, according to researchers at the French State Agricultural Research Institute. The DNA of Lactobacillus delbrueckii ssp. bulgaricus contains 1.8 million base pairs and is undergoing rapid development that is making the germ more and more genetically alienated from its original bacterial relatives.
Many of the bacterium's genes can be replaced by sequences from the germ Streptococcus thermophilus, which also ferments in yoghurt and forms cultures. Apparently, the common environment decisively shapes the development path of both germs, conclude the scientists working with Maarten van de Guchte.
Yogurt is created when lactic acid bacteria thicken milk, ferment lactose into lactic acid and produce characteristic flavorings. In just 5,000 years since yoghurt was deliberately produced by humans, the repeatedly inoculated L. delbrueckii has developed from a bacterium that may live in plants to a specialist that ferments in milk. Many proteins have become superfluous surprisingly quickly. In addition, van de Guchte and colleagues speculate that the roughly 250 identified, meanwhile non-functioning, pseudogenes will also fall victim to the ongoing streamlining process of the lactic acid fermenter in the future.