title: Production of enterolysin A by a raw milk enterococcal isolate exhibiting multiple virulence factors.
abstract: Even though enterococci are a common cause of human infection they can readily be isolated from a range of food sources, including various meat and dairy products. An enterococcal strain, DPC5280, which exhibits a broad spectrum of inhibition against many Gram-positive bacteria was recently isolated from an Irish raw milk sample. Characterization of the inhibition revealed that the strain exhibits haemolytic activity characteristic of the two-component lantibiotic cytolysin and also produces a heat-labile antimicrobial protein of 34 kDa. The latter protein displayed cell wall hydrolytic activity, as evidenced by zymogram gels containing autoclaved lactococcal cells. N-terminal sequencing of the purified protein yielded the sequence ASNEWS which is 100 % identical to enterolysin A (accession no. AF249740), a protein which shares 28 and 29 % identity to the Gly-Gly endopeptidases, lysostaphin and zoocin A, respectively. Indeed, amplification of entL from DPC5280 and sequencing revealed that the protein is 100 % identical to enterolysin A. The DPC5280 strain also contained the determinants associated with multiple virulence factors, including gelatinase, aggregation substance and multiple antibiotic resistance. The linkage of this cell-wall-degrading enzyme to other virulence factors in enterococci may contribute to the competitiveness of pathogenic enterococci when found in complex microbial environments such as food and the gastrointestinal tract.
authors.affiliation: Microbiology Department, University College Cork, Ireland.|Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: Rita M
authors.initials: RM
authors.lastname: Hickey
authors.affiliation: National Food Biotechnology Centre, University College Cork, Ireland.|Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: Denis P
authors.initials: DP
authors.lastname: Twomey
authors.affiliation: Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: R Paul
authors.initials: RP
authors.lastname: Ross
authors.affiliation: Microbiology Department, University College Cork, Ireland.|National Food Biotechnology Centre, University College Cork, Ireland.
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001430:Bacteriocins; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism; D003603:Cytotoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013293:Enterococcus faecalis / Q000378:metabolism* / Q000472:pathogenicity*; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006461:Hemolysis; D008892:Milk / Q000382:microbiology*; D008969:Molecular Sequence Data; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; D003603:Cytotoxins; D037521:Virulence Factors; C120351:cytolysin, Enterococcus faecalis