TABLE 1.

Bacterial strains and plasmids used in this study

L. lactis strain or plasmid	Characteristics and/or genotype	Source or reference
L. lactis strains
CRL264	Lac+ Pro+ Cit+ harboring pCIT264	26
CRL30	Lac+ Pro+ Cit−	13
IL1403	Trp+ plasmid-free	2
Plasmids
pAK80	Promoter selection vector containing the promoterless L. mesenteroides β-galactosidase (lacL and lacM) genes	11
pIL86	pAK80 derivative containing the lacLM genes under the control of the 457-bp als promoter region from Lactococcus bv. diacetylactis CRL264	This study
pIL91	pAK80 derivative containing the lacLM genes under the control of the 297-bp aldB promoter region from Lactococcus bv. diacetylactis CRL264	This study
pIL95	pAK80 derivative containing the lacLM genes under the control of the 280-bp aldC promoter region from Lactococcus bv. diacetylactis CRL264	This study
pIL77	pAK80 derivative containing the lacLM genes under the control of the 554-bp butBA promoter region from Lactococcus bv. diacetylactis CRL264	This study