Design of Lactococcus lactis Strains Producing Garvicin A and/or Garvicin Q, Either Alone or Together with Nisin A or Nisin Z and High Antimicrobial Activity against Lactococcus garvieae .

is a main ichthyopathogen in rainbow trout (, Walbaum) farming, although bacteriocinogenic with antimicrobial activity against virulent strains of this species have also been identified. Some of the bacteriocins characterized, such as garvicin A (GarA) and garvicin Q (GarQ), may show potential for the control of the virulent in food, feed and other biotechnological applications. In this study, we report on the design of strains that produce the bacteriocins GarA and/or GarQ, either alone or together with nisin A (NisA) or nisin Z (NisZ). Synthetic genes encoding the signal peptide of the lactococcal protein Usp45 (SP), fused to mature GarA () and/or mature GarQ () and their associated immunity genes ( and , respectively), were cloned into the protein expression vectors pMG36c, which contains the P constitutive promoter, and pNZ8048c, which contains the inducible P promoter. The transformation of recombinant vectors into lactococcal cells allowed for the production of GarA and/or GarQ by subsp NZ9000 and their co-production with NisA by subsp. DPC5598 and subsp. BB24. The strains subsp WA2-67 (pJFQI), a producer of GarQ and NisZ, and subsp WA2-67 (pJFQIAI), a producer of GarA, GarQ and NisZ, demonstrated the highest antimicrobial activity (5.1- to 10.7-fold and 17.3- to 68.2-fold, respectively) against virulent strains.