Efficacy of enterocin AS-48 against bacilli in ready-to-eat vegetable soups and purees

J Food Prot. 2007 Oct;70(10):2339-45. doi: 10.4315/0362-028x-70.10.2339.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacillus / drug effects*
  • Bacillus cereus / drug effects
  • Bacillus cereus / growth & development
  • Bacteriocins / pharmacology*
  • Colony Count, Microbial
  • Drug Synergism
  • Food Microbiology
  • Food Preservation / methods*
  • Food Preservatives / pharmacology*
  • Nisin / pharmacology
  • Temperature
  • Time Factors
  • Vegetables / microbiology*

Substances

  • Anti-Bacterial Agents
  • Bacteriocins
  • Food Preservatives
  • enterocin AS-48, Enterococcus faecalis
  • Nisin