False-positive fluorescence by pink salmon tissue and staphylococci in a rapid test for Escherichia coli.
Fluorescence from 4-methylumbelliferyl-beta-D-glucuronide (MUG) hydrolysis is a common, rapid method for determining Escherichia coli in water and food. False-positive fluorescence occurred when either pink salmon fillets were tested or beta-glucuronidase-positive Staphylococcus species were present in other fish products. Salmon fillet, E. coli, S. xylosus, and S. warneri produced 2, 17, 39, and 43 nmol of 4-methylumbelliferone per ml, respectively, in a one-step detection broth (lauryl salts tryptose broth with MUG) for E. coli after 48 h at 35 degrees C. These false-positive reactions need to be considered when testing fish products, especially those contaminated through human handling.
University of Alaska Fairbanks Fishery Industrial Technology Center, Alaska 99615-7401, USA. ffbhh@uaf.edu
B H
BH
Himelbloom
R C
RC
Pfutzenreuter
D000818:Animals; D001431:Bacteriological Techniques; D004926:Escherichia coli / Q000201:enzymology / Q000302:isolation & purification*; D005189:False Positive Reactions; D005453:Fluorescence; D005966:Glucuronidase / Q000378:metabolism; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism; D012474:Salmon / Q000382:microbiology*; D017747:Seafood / Q000382:microbiology; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013210:Staphylococcus / Q000201:enzymology
D006923:Hymecromone; C034888:4-methylumbelliferyl glucuronide; D005966:Glucuronidase