Production of enterotoxin A and thermonuclease by Staphylococcus aureus in legumes.
Growth, enterotoxin A (SEA) and thermonuclease (TNase) production of S. aureus (Strains CP 7 and FRI 722) was determined in media produced from the following heat or irradiation sterilized legumes: peas, black beans, mung beans, adzuki beans and soybeans. Media containing the five legumes alone or in combination with Brain Heart Infusion Broth (BHI) were tested. With the exception of heat-sterilized black beans and adzuki beans, S. aureus growth was excellent in all media with cell counts after 48 h (25 degrees C) exceeding 10(8) cfu/ml. In black beans and adzuki beans cell counts were 1-2 log-cycles lower. Enterotoxin A was produced in amounts of 33 to 72 ng/ml in BHI after 48 h. Almost no toxin was produced in the four different beans following heat or irradiation treatment; in peas the toxin concentration reached 14 to 15 ng/ml. In the medium prepared from irradiated soybeans and BHI the final toxin concentration was about the same as in BHI alone. In all the other media consisting of a combination of legumes with BHI toxin concentrations were three to four times higher than in BHI alone. Production of thermonuclease showed variation and did not always correlate with enterotoxin production.
Department of Agricultural and Food Microbiology, University of Bonn, F.R.G.
L
L
Neumayr
J
J
Krämer
D015169:Colony Count, Microbial; D003470:Culture Media; D004768:Enterotoxins / Q000096:biosynthesis*; D007887:Fabaceae / Q000382:microbiology*; D005516:Food Microbiology; D008836:Micrococcal Nuclease / Q000096:biosynthesis*; D010946:Plants, Medicinal; D013211:Staphylococcus aureus / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
D003470:Culture Media; D004768:Enterotoxins; C026066:enterotoxin A, Staphylococcal; D008836:Micrococcal Nuclease