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Prevention and treatment of mastitis in dairy cows with bacteriocins produced by Enterococcus faecalis

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dc.contributor.advisor Dicks LMT, Prof en
dc.contributor.author Davidse E en
dc.date.accessioned 2016-09-22T08:34:29Z
dc.date.available 2016-09-22T08:34:29Z
dc.date.submitted 2003 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/30983
dc.description.abstract The effect of the bactertocin-like peptide AS-48, produced by "Enterococcus faecalis" FAIRE 92, was tested against a mastitis isolate of "Staphylococcus aureus" in an "in vivo" and "in vitro" study. During initial tests peptide AS-48 showed no significant activity towards "S. aureus", even with a ten-fold concentrated cell-free supernatant. Activity was obtained only after purification with Triton X-1 14 phase partitioning, followed by cation exchange chromatography. Titers for the purified peptide varied between 3200 and 12800 AU/ml. The purified peptide also exhibited activity towards "Streptococcus agalactiae" and "Streptococcus dysgalactiae", but not against "Escherichia coli". The size of peptide AS-48 was determined at 7150 Da, based on electronspray mass spectrometry and SDS-PAGE. Complete inhibition of cell growth was obtained by adding 1ml of the purified peptide (3200 AU/ml) to 100 ml of cells of "S. aureus" in the lag growth phase. When the same concentration of peptide AS-48 was added to a culture of "S. aureus" in mid-exponential growth, a slight decrease in viable cell numbers was recorded, which lasted for only 30 mm. Cell growth commenced thereafter. "In situ" experiments in cows were done with purified peptide AS-48, encapsulated in liposomes. These "in vivo" studies were conducted by administering peptide AS-48 (6400 AU/ml) to different udder quarters. In a prevention trial, i.e. where quarters were pretreated with peptide AS-48, a reduction close to 90 percent in the viable cell numbers of "S. aureus" was recorded relative to the control quarters, which were not treated with the peptide. A 50 percent reduction in somatic cell count (SCC) was recorded. In the treatment trial, i.e. infected quarters treated with peptide AS-48, a reduction of up to 94 percent in viable cell numbers of "S. aureus" was recorded. In the same quarters, a reduction in SCC amounted to almost 80 percent. A recombinant strain was constructed by conjugating plasmid 92 (p92), encoding peptide AS-48, from "Enterococcus faecalis" FAIRE 92 to "E. faecalis" FA2/Ent, which produces enterocins l07lA and 1071B. Southern blot hybridization experiments revealed the presence of plasmid p92 in the recipient strain without the loss of plasmid pEF1071, which encodes enterocins 1071A and 1071B. All three antimicrobial peptides, i.e. enterocin 1071A, enterocin 1071B and peptide AS-48, were produced in transconjugant FA2/Ent/AS-48. The spectrum of antimicrobial activity of the transconjugant was greater than that recorded for strains FA2/Ent and FAIRE 92, respectively and included "E. faecalis, Bacillus cereus, Lactobacillus acidophilus, Lactobacillus easel, Lactobacillus curvatus, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus sakei, Leuconostoc cremoris, Leuconostoc pentosaceus, Staphylococcus carnosus" and "S. aureus". These organisms are not inhibited by strain FA2/Ent. However, low levels of peptide AS-48 was produced by strain FA2/Ent/AS-48. Further research in fermentation and gene expression will be needed before the transconjugant "E. faecalis" FA2/Ent/AS-48 may be used in the treatment of mastitis. en
dc.language English en
dc.subject Microbiology en
dc.title Prevention and treatment of mastitis in dairy cows with bacteriocins produced by Enterococcus faecalis en
dc.type Masters degree en
dc.description.degree MSc en

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