Table 1.

Bacterial strains and plasmids used in this study

Strain/plasmid	Genotype/marker/descriptiona	Reference/source
L. lactis subsp. cremoris
MG1363	Plasmid-free derivative of L. lactis NCDO 712 cured of ΦT712 prophage	20
MG1363 Δcfa	cfa mutant derivative of MG1363	This study
MG1363 pDL278	MG1363 harboring pDL278, Spr	This study
MG1363 Δcfa pDL278	MG1363 Δcfa harboring pDL278, Spr	This study
MG1363 Δcfa pDLcfa12A3	MG1363 Δcfa harboring pDLcfa12A3, Spr	This study
E. coli
K-12 and ER2738	General cloning strains	Invitrogen
EC101	E. coli JM101 with repA from pWV01 integrated into the chromosome; host strain used for construction of pGID023-derivative plasmids	35
Plasmids
pDL278	E. coli-L. lactis shuttle vector (6.6 kbp), Spr	11
pDLcfa12A3	pDL278-derivative vector used to express the cfa gene under an endogenous promoter, Spr	This study
pGID023	Shuttle vector (8.2 kbp) for E. coli and L. lactis; derivative of pJDC9 containing the pE194 replication functions (thermosensitive ori); used as an unstable integration vector, Emr	28
pTMH1	Integration plasmid and pGID023 derivative containing the cfa gene carrying a 28-bp internal deletion (nucleotides 514 to 541 of the coding sequence), Emr	This study

^aEm^r, erythromycin resistance (10 μg ml⁻¹ for L. lactis subsp. cremoris; 250 μg ml⁻¹ for E. coli); Sp^r, spectinomycin resistance (1,000 μg ml⁻¹ for L. lactis subsp. cremoris; 50 μg ml⁻¹ for E. coli).