TABLE 1.

Strains and plasmids used in this study

Strain or plasmidGenotype or descriptionReference or source
L. lactis strains
    MG1363Plasmid-free and prophage-cured derivative of NCDO71216
    NZ3900MG1363 derivative, used as wild-type control (ΔlacF pepN::nisR-nisK)12
    PH3960NZ3900 derivative carrying a deletion in alralr)This study
    GB3960PH3960 derivative carrying a deletion in acmAalr acmAΔ1)This study
    MG1363acmAΔ1MG1363 derivative carrying a deletion in acmA (acmAΔ1)9
    MG1363 (dltD)MG1363 derivative carrying an ISS1 insertion in dltD (dltD::ISS1)13
    MG1363 (dltD acmAΔ1)MG1363 (dltD) derivative carrying a deletion in acmA (dltD::ISS1 acmAΔ1)This study
    NZ9000MG1363 pepN::nisRK30
    NZ9700Nisin producing transconjugant of NZ9000 containing the nisin-sucrose transposon Tn527629
Plasmids
    pINTAAIntegration plasmid used for the introduction of a 701-bp deletion in acmA; Emr9
    pGIP011PJDC9 derivative containing an internal fragment of alr from MG1363; Emr23
    pGIP016PGIP011 derivative containing an in frame deletion of alr from MG1363; EmrThis study
    pNG3041Plasmid used for the nisin induced overexpression of MSA2cA; CmrLaboratory collection