Antimicrobial activity and stability of partially purified bacteriocies produced by Propionibacterium freudenreichii ssp. freudenreichii and ssp. shermanii

摘要

In the last decade a few bacteriocins synthesized by Propionibacterium were described. Almost all of them are produced by P. thoenii and P. jensenii species and only a limited number of reports is available on the antimicrobial activity of other species. In the present work bacteriocin preparations obtained from two strains of P.. freudenreichii ssp, freudenreichii and one of P. freudenreichii ssp. shermanii were partially characterized, including their antimicrobial spectrum and stability. All preparations were active against the examined bacteria of Lactobacillus (L. acidophilus, L. casei, L. delbrueckii and L. helveticus) and some strains of Propionibacterium Crude bacteriocins also showed bacteriostatic activity against Gram-negative bacteria and fungistatic activity against moulds belonging to the Alternaria and Fusarium genera. Bacteriocin preparations were heat-stable and did not lose their activity in the range of pH from 4.5 to 7.0. They were also stable in the presence of organic solventssuch as ethanol, isopropanol, hexane and chloroform at the concentration of 1 mg mL~(-1); however, under the influence of some solvents an increase in bacteriostatic activity was observed It could indicate a formation of aggregates by active proteins. The activity of all crude bacteriocins was significantly reduced when SDS at concentrations of 1 to 20 mg mL~(-1) was used.