title: Efficacy of enterocin AS-48 against bacilli in ready-to-eat vegetable soups and purees.
abstract: The broad-spectrum bacteriocin enterocin AS-48 was tested for biopreservation of ready-to-eat vegetable foods (soups and purees) against aerobic mesophilic endospore-forming bacteria. By adding AS-48 (10 microg/ml), Bacillus cereus LWL1 was completely inhibited in all six vegetable products tested (natural vegetable cream, asparagus cream, traditional soup, homemade-style traditional soup, vegetable soup, and vichyssoise) for up to 30 days at 6, 15, and 22 degrees C. A collection of strains isolated from spoiled purees showed slightly higher resistance to AS-48 in the order Paenibacillus sp. > Bacillus macroides > B. cereus, although they were also completely inhibited in natural vegetable cream by AS-48 at 10 microg/ml. However, cocktails of five or eight strains composed of B. cereus (three strains), B. macroides (two strains), and Paenibacillus sp., Paenibacillus polymyxa, and Paenibacillus amylolyticus showed higher bacteriocin resistance with AS-48 of up to 50 microg/ml required for complete inactivation in natural vegetable cream stored at 22 degrees C. Repetitive extragenic palindromic sequence-based PCR (REP-PCR) analysis showed that paenibacilli (along with some B. cereus) was the predominant survivor in the cocktails after bacteriocin treatment. To increase the effectiveness of enterocin AS-48, the bacteriocin was tested (at 20 microg/ml) against the eight-strain cocktail in natural vegetable cream in combination with other antimicrobials. The combination of AS-48 and nisin had a slight but significant additive effect. Bactericidal activity was greatly enhanced by phenolic compounds (carvacrol, eugenol, geraniol, and hydrocinnamic acid), achieving a rapid and complete inactivation of bacilli in the tested puree at 22 degrees C.
authors.affiliation: Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071-Jaén, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Grande
authors.forename: Hikmate
authors.initials: H
authors.lastname: Abriouel
authors.forename: Rosario
authors.initials: R
authors.lastname: Lucas López
authors.forename: Eva
authors.initials: E
authors.lastname: Valdivia
authors.forename: Nabil
authors.initials: N
authors.lastname: Ben Omar
authors.forename: Magdalena
authors.initials: M
authors.lastname: Martínez-Cañamero
authors.forename: Antonio
authors.initials: A
authors.lastname: Gálvez
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects*; D001409:Bacillus cereus / Q000187:drug effects / Q000254:growth & development; D001430:Bacteriocins / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004357:Drug Synergism; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D009561:Nisin / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D014675:Vegetables / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D005520:Food Preservatives; C466236:enterocin AS-48, Enterococcus faecalis; D009561:Nisin