Antimicrobial-producing wild lactococci isolated from artisanal and non-dairy origins

Wild lactococcal strains with diverse properties isolated from dairy and non-dairy origins and characterised by their flavour-forming abilities were tested for antagonistic activities to assess their potential for use as new starter cultures. Thirty-two of seventy-nine strains examined inhibited the growth of indicator strains in an agar-well diffusion assay. The bacteriocins produced by these strains were characterised on the basis of their susceptibility to proteolytic enzymes and to boiling for 30 min. These bacteriocins were placed into four groups: raisin, diplococcin, lactococcin, and unknown bacteriocin-like compounds. Seventeen strains appeared to produce raisin, which was confirmed by polymerase chain reaction (PCR) and by HPLC. Eight of the 17 strains produced raisin A and nine produced raisin Z. Three of the latter strains produced higher concentrations of raisin Z than the control strain. The technologically important traits in these strains have been examined, which allowed the selection of those strains as part of tailor-made starter cultures for the manufacture of dairy products. (C) 2002 Elsevier Science Ltd. All rights reserved.