Biocontrol of Escherichia coli O157 with O157-specific bacteriophages.
Escherichia coli O157 antigen-specific bacteriophages were isolated and tested to determine their ability to lyse laboratory cultures of Escherichia coli O157:H7. A total of 53 bovine or ovine fecal samples were enriched for phage, and 5 of these samples were found to contain lytic phages that grow on E. coli O157:H7. Three bacteriophages, designated KH1, KH4, and KH5, were evaluated. At 37 or 4 degrees C, a mixture of these three O157-specific phages lysed all of the E. coli O157 cultures tested and none of the non-O157 E. coli or non-E. coli cultures tested. These results required culture aeration and a high multiplicity of infection. Without aeration, complete lysis of the bacterial cells occurred only after 5 days of incubation and only at 4 degrees C. Phage infection and plaque formation were influenced by the nature of the host cell O157 lipopolysaccharide (LPS). Strains that did not express the O157 antigen or expressed a truncated LPS were not susceptible to plaque formation or lysis by phage. In addition, strains that expressed abundant mid-range-molecular-weight LPS did not support plaque formation but were lysed in liquid culture. Virulent O157 antigen-specific phages could play a role in biocontrol of E. coli O157:H7 in animals and fresh foods without compromising the viability of other normal flora or food quality.
Kudva
I T
IT
Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, Idaho 83843, USA.
Jelacic
S
S
Tarr
P I
PI
Youderian
P
P
Hovde
C J
CJ
D000818:Animals; D001433:Bacteriolysis; D002417:Cattle; D003090:Coliphages / Q000302:isolation & purification / Q000502:physiology*; D019453:Escherichia coli O157 / Q000276:immunology / Q000502:physiology* / Q000821:virology*; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000096:biosynthesis / Q000276:immunology; D008242:Lysogeny; D019081:O Antigens / Q000276:immunology; D012756:Sheep; D013045:Species Specificity; D010948:Viral Plaque Assay
D008070:Lipopolysaccharides; D019081:O Antigens