Isolation and partial characterization of Enterocin CRL 1692 produced by Lactic Acid Bacteria from new born calves

MALDONADO NC, SILVA DE RUIZ C, SESMA F, NADER-MACÍAS ME

Saint-Malo

Simposio; Second International Symposium on Antimicrobial Peptides: Food, Veterinary, Medical and Novel Application; 2009

French Institute INRA

The design of novel probiotic products for the prevention of calves’ diseases to replace antibiotics is a promising alternative in animal feed. Probiotics are used as viable microorganisms to modify the intestinal microbial balance, prevent pathogens colonization, and improve host´s health [1]. The application of bacteriocin combined with LAB (Lactic Acid Bacteria) as a potential probiotic product for the prevention of calf diseases is the final objective of our group. The aim of this work was to isolate and characterize bacteriocins produced by strains isolated from new born calves’ faeces of the Dairy Area of Trancas, Argentine. Nineteen seven strains of LAB were screened for bacteriocin production by the well diffusion assay against same calf pathogens and related bacteria. The microorganisms used for the detection of antagonistic substances were Salmonella Dublin, Salmonella infantis, Yersinia enterocolitica, Escherichia coli, Streptococcus uberis, Streptococcus dysgalactiae, Klebsiella sp, Salmonella thyphimurium, Staphylococcus aureus, Staphylococcus epidermidis and Listeria sp. Those that showed positive results were treated with catalase and neutralized to detect the bacteriocinogenic strains. One strain, identified by molecular biology techniques as Enterococcus faecium CRL 1692, produced a bacteriocin active against Listeria sp and Streptococcus uberis. To determine the chemical nature of the bacteriocin, the effect of proteinase K, -chymiotrypsin and trypsin was evaluated, being the bacteriocin activity affected by all the treatments. Molecular assays were performed to identify the type of bacteriocin, and the identification of the structural genes was performed by PCR amplification. The genetic identification of the bacteriocin produced by Enterococccus faecium CRL 1692 showed to be (or almost identical) identical to enterocin A. In order to determine if this bacteriocin can be combined with other LAB strains with beneficial properties, the pattern of inhibition against those bacteria was studied. The use of bacteriocins as antibacterial substances may provide several advantages over the use of antibiotics, mainly by their spread of resistance. The combination of LAB and bacteriocins could be applied for the design of novel products to be used in animal nutrition for dairy farms as probiotics. References. [1] Nousiainnen J, Javanainen P & Setälä J (2004) Lactic Acid Bacteria as Animal Probiotics. In: Lactic Acid Bacteria Microbiological and functional Aspects Third Edition, pp 547-580 (Eds S Saminen, A von Wright & A Ouwehand). New York, USA: Marcel Dekker, Inc