Complete DNA Sequence of Lactococcus lactis Adds Flavor to Genomics

With the publication of the long-awaited genome sequence ofLactococcus lactis ssp. lactis IL1403, Bolotin et al. (2001) have set the stage for functional and comparative genomics of an important group of industrial microorganisms, that is, the lactic acid bacteria (LAB). LAB are widely used for starting industrial fermentations of milk, vegetables, meat, and fish. L. lactisis used in cheesemaking, as it is involved in casein degradation, in acidification by formation of lactate, and in the formation of flavor compounds. Other LAB, such as Streptococcus thermophilus,Lactobacillus delbrueckii subsp. bulgaricus, and certain Bifidobacteria, are used for yogurt production, whereas Proprionibacteria and other species contribute to the product characteristics of Swiss-type cheeses. L. lactis is the major starter for Cheddar production; for a Dutch cheese such as Gouda, a complex starter culture containing >100 different strains of LAB is used.

L. lactis is by far the best characterized LAB with respect to its physiology, metabolic pathways, and regulatory mechanisms. The ease of genetic modification of various species of LAB and the existence of a worldwide network of LAB researchers have greatly stimulated fundamental and applied research in LAB (Gasson and de Vos 1994; Konings et al. 1999). Industrial applications are directed mainly toward improvement of flavor, texture, and preservation characteristics of fermented products as well as enhancement of industrial robustness of starter cultures. Novel uses of LAB, such as in oral vaccines or in preparation of functional foods or their direct application as a probiotic culture, are also being explored (Delcour et al. 1999). For oral …