Genetically improved starter strains: opportunities for the dairy industry

Milk can be fermented to a variety of different products varying in appearance, flavour, texture and health beneficial properties. The art of producing such different products is based on different technologies and in the selection of the lactic acid bacteria used in the fermentation process. The emergence of new technologies such as molecular biology and genetics advanced on the one hand the possibilities to use these techniques for selection to screen thousands of natural strains and mutants, and on the other hand to improve strains by direct genetic engineering. This article illust:rates. examples of both applications in starter strain development for dairy fermentations. Furthermore, it partitions the nature of genetic modifications into three groups: (i) one-step genetic events like deletions, gene amplifications, plasmid insertions or losses; (ii) multi-step genetic rearrangements with DNA of a same species; and (iii) trans-species genetic modifications. The nature of the genetic alteration has an impact on the safety assessment and legal implications in different countries. (C) 1999 Elsevier Science Ltd. All rights reserved.