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Aims: To determine the activity of enterocin AS-48 against ropy-forming Bacillus licheniformis from cider. Methods and Results: Enterocin AS-48 was tested on B. licheniformis LMG 19409 from ropy cider in MRS-G broth, fresh-made apple juice and in two commercial apple ciders (A and B). Bacillus licheniformis was rapidly inactivated in MRS-G by 0·5 μg ml−1AS-48 and in fresh-made apple juice by 3 μg ml−1. Concentration-dependent inactivation of this bacterium in two commercial apple ciders (A and B) stored at 4, 15 and 30°C for 15 days was also demonstrated. Counts from heat-activated endospores in cider A plus AS-48 decreased very slowly. Application of combined treatments of heat (95°C) and enterocin AS-48 reduced the time required to achieved complete inactivation of intact spores in cider A to 4 min for 6 μg ml−1 and to 1 min for 12 μg ml−1. D and z values also decreased as the bacteriocin concentration increased. Conclusion: Enterocin AS-48 can inhibit ropy-forming B. licheniformis in apple cider and increase the heat sensitivity of spores. Significance and Impact of the Study: Results from this study support the potential use of enterocin AS-48 to control B. licheniformis in apple cider. [ABSTRACT FROM AUTHOR]

Aims: To characterize bacteriocin production, antimicrobial spectrum and plasmid content in bacteriocinogenic enterococci from foods. Methods and Results: Bacteriocinogenic Enterococcus faecium (14 isolates) and Enterococcus faecalis (three isolates) showed two different patterns of bacteriocin production in liquid broth: exponential-phase and stationary-phase production. Bacteriocin concentrates from all enterococci were inactivated by trypsin, but seldom by heat (100–117°C), extremes of pH (2·0 to 9·0) or reducing agents (such as dithiothreitol). All bacteriocin concentrates were active against Listeria innocua and Listeria monocytogenes, and most were also active against many Ent. faecalis and Ent. faecium isolates. Enterococci clustered in three main groups according to their plasmid content (which included plasmids from 2·0 to 53 kb). Several isolates from different foods showed almost identical plasmid profiles. The enterocin P structural gene ( entP) was detected by hybridization on plasmids of c. 19, 26 and/or 35–38 kb. Conclusions: Enterococci from food show different patterns of bacteriocin production and different plasmid content in spite of carrying similar bacteriocin-encoding genes. Significance and Impact of the Study: This study provides information on the diversity of bacteriocinogenic enterococci from food sources carrying apparently similar enterocin genes. [ABSTRACT FROM AUTHOR]

mª.t. garcía, r. lucas, h. abriouel, n. ben omar, r. pérez, mª.j. grande, m. martínez-cañamero and a. gálvez. 2004.Activity of the bacteriocin EJ97 produced byEnterococcus faecalisEJ97 against strains of‘ Bacillus macroides/B. maroccanus’ isolated from spoiled zucchini purée was investigated.The influence of several factors like bacteriocin concentration, incubation temperature, pH, growth medium and chemical perservatives on bacteriocin activity was investigated. Enterocin EJ97 [2 arbitrary units (AU) per millilitre] had a marked bactericidal effect on strain INRA P53-2 after 4 h of incubation at 37°C, 24 h at 15°C or 48 h at 4°C. Activity was markedly reduced at pH values of 5·0 and 9·0, but was potentiated by sodium nitrite, sodium benzoate, sodium lactate and sodium tripolyphosphate. Inhibition of strain INRA P53-2 in a commercial vegetable purée required a 10-fold higher bacteriocin concentration. Strain EJ97 was able to grow and produce bacteriocin on vegetable purée, but no inhibition of strain INRA P53-2 was detected.The concentration-dependent bactericidal activity of enterocin EJ97 against strain INRA P53-2 was higher at 37°C and neutral pH, and was potentiated by chemical preservatives. Although enterocin EJ97 was less active in vegetable purée, the concentrations providing bactericidal activity in this food matrix are practical for commercial use.Enterocin EJ97 may have a potential for use in the prevention of food spoilage caused by‘ B. macroides/B. maroccanus’. [ABSTRACT FROM AUTHOR]