Table 2 Bacterial strains and plasmids
Strain or plasmid | Relevant properties | Reference or source |
|---|---|---|
Strains | ||
 E. coli TOP10 | Cloning host | Invitrogen |
 B. subtilis QK02 | QK producing bacterium, wild strain | CCTCC |
 L. lactis MG1363 | Subsp. cremoris, plasmid-free | Our lab |
 L. lactis NZ9000 | Derivative of MG1363 with integration nisRK into chromosome | [19] |
 L. lactis NZ3900 | Derivative of NZ3000 with integration nisRK into chromosome; ∆lacF | [19] |
 L. bulgaricus ATCC 11842 | Type strain | [37] |
 L. plantarum ST-III | Wild strain | [34] |
 L. casei | Wild strain | Our lab |
 L. paracasei | Wild strain | Our lab |
 S. thermophilus | Wild strain | Our lab |
Plasmids | ||
 pUC19-qk′ | ApR, pUC19 containing the optimized gene qk′ | TsingKe |
 pNZ8048 | CmR, P nisA , L. lactis expression vector | [35] |
 pNZ8149 | lacF, P nisA , L. lactis food grade expression vector | [36] |
 pRF01 | lacF, pNZ8149 derivate containing spUsp downstream of P nisA | This study |
 pRF02 | lacF, pRF01 with qk downstream of spUsp | This study |
 pRF02H | lacF, pRF02 containing qk with a His-tag | This study |
 pRF03 | CmR, pNZ8048 derivate carrying spUsp-qk downstream of P nisA | This study |
 pRF03H | CmR, pRF03 containing qk with a His-tag | This study |
 pRF04H | CmR, pRF03 containing qk’ with a His-tag | This study |
 pRF05H | CmR, pRF03 containing qkpro’ with a His-tag | This study |
 pRF06H | CmR, pRF03 derivate containing one LysM with a His-tag from acmA fused to the 3′ end of qk | This study |
 pRF07H | CmR, pRF06H derivate containing three LysM | This study |
 pRF08H | CmR, pRF06H derivate containing five LysM | This study |
 pRF09H | CmR, pRF03H containing one LysM from acmA between spUsp and qk | This study |