Jc. Piard et al., CONJUGAL TRANSFER OF THE DETERMINANTS FOR BACTERIOCIN (LACTICIN-481) PRODUCTION AND IMMUNITY IN LACTOCOCCUS-LACTIS SUBSP LACTIS CNRZ-481, FEMS microbiology letters, 112(3), 1993, pp. 313-318
The lacticin 481-producer (Lct+), L. lactis subsp. lactis (L. lactis)
CNRZ 481 harbours 5 plasmids of 6.5, 7.5, 20, 37 and 69 kb. Novobiocin
treatment of L. lactis 481 led to the appearance of lacticin 481 defi
cient variants which had all lost the 69 kb plasmid. Conjugal transfer
of the lacticin 481 structural gene (lct) into the plasmid free strai
n L. lactis IL1441 yielded Lct+ transconjugants at a 10(-4) frequency,
which carried a plasmid with an apparent size of 120-130 kb. Southern
hybridization analyses showed that the lct gene was located on the 69
kb plasmid in L. lactis 481 and on the 120-130 kb plasmid in the tran
sconjugants. The lct gene was in higher copy number in transconjugants
than in the parental strain resulting in two-fold higher lacticin 481
production in the former strain.