The review focusses on the use of genetic techniques to manipulate bac
teria that are important to the diary industry. Both classical and mol
ecular approaches have been used to improve strains involved in yoghur
t and cheese production. Examples are provided of methods for; increas
ing efficiency of substrate conversion, regulating the production of f
lavour enhancing metabolites, and developing starter cultures resistan
t to bacteriophage and bacteriocin attack. The possible applications o
f these systems are discussed.