Diverse antimicrobial killing by Enterococcus faecium E 50-52 bacteriocin.

An effective bacteriocin was identified and characterized. Lactic acid bacteria were screened against Campylobacter jejuni. One bacteriocin producer, Enterococcus faecium (NRRL B-30746), was studied. The isolate was grown, and the bacteriocin was purified to single-band homogeneity. Biochemical traits indicated that the peptide was a Class IIa bacteriocin, and it was named E 50-52. The bacteriocin had a molecular weight of 3339.7 and an isoelectric point of 8.0. The minimal inhibitory concentrations of E 50-52 against C. jejuni, Yersinia spp., Salmonella spp., Escherichia coli O157:H7, Shigella dysenteriae, Morganella morganii, Staphylococcus spp., and Listeria spp. ranged from 0.025 to 32 microg/mL. In therapeutic broiler trials, oral treatment with E 50-52 reduced both C. jejuni and Salmonella enteritidis by more than 100,000-fold in the ceca, and systemic S. enteritidis was reduced in the liver and spleen. The wide range of antibacterial activity of bacteriocin E 50-52 against pathogens provides a promising alternative to antibiotics.

Paenibacillus polymyxa purified bacteriocin to control Campylobacter jejuni in chickens.

Campylobacter spp. cause numerous foodborne diseases. Poultry is thought to be a significant source of this zoonosis. Although many interventions designed to control this agent have been researched, none have succeeded. We evaluated a bacteriocin-based treatment to reduce Campylobacter jejuni colonization in poultry. A previously described purified bacteriocin (class IIa; molecular mass, 3,864 Da), secreted by Paenibacillus polymyxa NRRL-B-30509, was microencapsulated in polyvinylpyrrolidone, and 0.25 g of the purified bacteriocin was incorporated into 1 kg of chicken feed. One-day-old chickens were orally challenged and colonized with one of four isolates of C. jejuni, then reared in isolation facilities. Birds were provided ad libitum access to standard broiler starter feed and water for 7 days until 3 days before sampling, when only the treated groups of birds were provided the bacteriocin-emended feed described. In each of the eight (four by two replicates) trials, significant reductions in colonization by C. jejuni were observed (P < or = 0.05). As an example of this highly consistent data, in the first trial, 10 untreated 10-day-old chickens were colonized at a mean log 7.2 + 0.3 CFU/g of feces, whereas none of the 10 bacteriocin-treated 10-day-old chickens were colonized with detectable numbers of C. jejuni. Bacteriocin treatment dramatically reduced both intestinal levels and frequency of chicken colonization by C. jejuni. Feeding bacteriocins before poultry slaughter appears to provide control of C. jejuni to effectively reduce human exposure. This advance is directed toward on-farm control of pathogens, as opposed to the currently used chemical disinfection of contaminated carcasses.

Isolation of Bacillus circulans and Paenibacillus polymyxa strains inhibitory to Campylobacter jejuni and characterization of associated bacteriocins.

We evaluated anti-Campylobacter activity among 365 Bacillus and Paenibacillus isolates from poultry production environments. One novel antagonistic Bacillus circulans and three Paenibacillus polymyxa strains were identified and further studied. Cell-free ammonium sulfate precipitate (crude antimicrobial preparation) was obtained from each candidate culture. Zones of Campylobacter growth inhibition surrounding 10 microl of this crude antimicrobial preparation were quantified using a spot test. Campylobacter growth resumed when the preparation was preincubated with selected protease enzymes, demonstrating peptide characteristics consistent with a bacteriocin. These peptides were further purified using combinations of molecular mass resolution and ion exchange chromatography. Molecular masses of the peptides were estimated at approximately 3,500 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing was used to determine the pI values of the peptides. Amino acid sequences of the bacteriocins and more precise molecular masses were obtained by matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF) analysis. The bacteriocin from P. polymyxa NRRL B-30507 had a pI of 4.8, that from P. polymyxa NRRL B-30509 had a pI of 7.2, that from P. polymyxa NRRL B-30508 had a pI of 4.8, and that from B. circulans NRRL B-30644 had a pI of 7.8. The amino acid sequences were consistent with those of class IIa bacteriocins. These antagonists and the corresponding bacteriocins may be useful in the control of Campylobacter infection in poultry.