TABLE 3

Characteristics of bacterial strains and plasmids used in this study

Strain or plasmidDescriptionSource or reference
Strains
    S. agalactiae
        GD201008-001 serotype Ia strainA virulent strain of S. agalactiae isolated from tilapia with meningoencephalitis in ChinaCollected in our laboratory
        Δcas9 mutantcas9 gene deletion mutant of GD201008-001This study
        Δcas9 complemented strain (CΔcas9)GD201008-001 Δcas9 complemented with vector pSET2::cas9; SpcrThis study
        ΔregR mutantregR gene deletion mutant of GD201008-001This study
        Δcas9-regR mutantcas9 and regR gene double-deletion mutant of GD201008-001This study
        ΔregR complemented strain (CΔregR)GD201008-001 ΔregR complemented with vector pSET2::regR; SpcrThis study
        ΔregR complemented Δcas9 strain (CregRcas9)GD201008-001 Δcas9-regR complemented with vector pSET2::regR; SpcrThis study
        regR-overexpressing strain (OE regR)regR gene-overexpressing wild-type strain GD201008-001 containing the vector pSET2::regR; SpcrThis study
    E. coli DH5αUsed for production of recombinant plasmidsInvitrogen
Plasmids
    pSET4SThermosensitive suicide vector for gene replacement in Streptococcus replication of pG+ host3 and pUC19; lacZ′ Spcr50
    pSET2E. coli-Streptococcus shuttle vector; Spcr51
    pSET4S::cas9Recombinant vector with pSET4S background, designed for knockout of cas9; SpcrThis study
    pSET2::cas9Complementation vector with pSET2 background containing the promoter followed by full-length cas9 ORFThis study
    pSET4S::regRRecombinant vector with pSET4S background, designed for knockout of regR; SpcrThis study
    pSET2::regRComplementation vector with pSET2 background containing the promoter followed by the full-length regR ORF