Table 1 Bacterial strains and plasmid vectors used in the present study
From: Nisin inducible production of listeriolysin O in Lactococcus lactis NZ9000
Strain or plasmid name | Description | Reference or source |
|---|---|---|
E. coli Top10 | Chemically-competent intermediate host, plasmid free | Invitrogen |
E. coli BL21 | Chemically-competent E. coli, used in this study as an intermediate host for pQE30, plasmid free | Novagen |
Listeria monocytogenes EGD-e serovar 1/2a | Wild type Listeria monocytogenes | [32] |
Lactococcus lactis NZ9700 | Nisin producer strain | [13] |
Lactococcus lactis NZ9000 | L. lactis subsp. Cremoris MG1363 carrying nisRK on the chromosome | [13] |
L. lactis NZ9000 (pNZPnisA:CYTO-LLO) | Lactococcus lactis NZ9000 harbouring pNZPnisA:CYTO-LLO plasmid and over-expressing LLO upon nisin induction | This study |
pQE30 | Expression vector using phage T5 promoter and adding an N-terminus six-His tag to the expressed protein, AmpR (ampicillin resistant) | Qiagen |
pQE30/hly | pQE30 vector with hly gene (without signal sequence) inserted between Bam HI and Pst I restriction sites. | This study |
pNZ8048 | E. coli-L. lactis shuttle vector containing PnisA promoter and start codon in Nco I site, CmR (chloramphenicol resistant) | [13] |
pNZPnisA:CYTO-LLO | Modified pNZ8048 containing PnisA promoter (Nco I site eliminated) with downstream His-tagged hly gene, CmR | This study |