SIMILARITY OF BACTERIOCINS FROM SPOILED MEAT LACTIC-ACID BACTERIA

One hundred and thirty-nine lactic acid bacteria isolated from spoiled vacuum-packaged vienna sausages were screened far bacteriocin product ion. Five bacteriocinogenic strains were identified and their bacterio cins partially characterized All five bacteriocins were sensitive to p roteolytic enzymes, but were unaffected by catalase, lysozyme and chlo roform. The compounds were heat stable up to 100 degrees C for twenty minutes, and were active from pH 2.0 to 11.0. Highest bacteriocin acti vity was recorded under acidic conditions and activity decreased with increasing alkalinity. The optimum temperature for bacteriocin product ion, which was a growth associated phenomenon, was 25 degrees C to 30 degrees C. Maximum activity levels were reached during the late logari thmic phase of growth, but decreased in the stationary phase. Agarose gel electrophoresis revealed plasmids in the range of 24 kb to 76 kb. Plasmids from five strains hybridized to a 36-mer probe homologous to the N-terminal region of the leucocin A protein, a 23-mer probe homolo gous to the biosythesis gene of leucocin A, and an 18-mer probe homolo gous to the ATP transporter gene of leucocin E-TA33a, suggesting a deg ree of homology with the leucocin A structural gene and implicating th ese plasmids in bacteriocin production. A 2-kb fragment from a 76-kb p lasmid in one of the five bacteriocinogenic stains (Leuconostoc parame senteroides LA7a) was cloned into pUC118. Nucleotide sequencing reveal ed a 37 amino-acid bacteriocin preceded by a 24 amino-acid residue lea der peptide and showed that this bacteriocin and its pre-peptide were the same as leucocin B-TA11a.