Method and composition for detecting bacterial contamination in food products
AssigneeBioControl Systems, Inc.
InventorsDavid E. Townsend, Chun-ming Chen
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Abstract
This invention relates to a method for detecting the existence or measuring the concentration of total viable bacteria in a test sample from a food product. A medium is provided which contains three or more different enzyme substrates each having a nutrient moiety and a detectable moiety linked together. When a substrate is hydrolysed by a bacterial enzyme to create a separate detectable moiety, it causes or produces a detectable signal. These substrates produce detectable signals when any one of a phosphatase enzyme, a glycosidase enzyme or a peptidase enzyme is present in the medium.
Claims17
A method for detecting the presence or measuring the concentration of bacteria in a food product, comprising the steps of:
- providing a bacterial growth medium formulated for food testing, which comprises a first enzyme substrate for a phosphatase, a second enzyme substrate for -a glycosidase, and a third enzyme substrate for a peptidase, wherein said first, second and third enzyme substrates cause or produce an identical type of detectable signal when hydrolyzed by their respective enzymes;
- inoculating said medium with said food product and incubating said medium under a condition suitable for bacterial growth for a period of time;
- and
- detecting or measuring the identical type of detectable signal as an indication of the presence or the concentration of bacteria in said food product;
- wherein said first enzyme substrate comprise a substrate for alkaline phosphatase, said second enzyme substrate comprises a substrate for β-D-glucosidase, and said third enzyme substrate comprises a substrate for L-alanine-7-aminopeptidase.
A method for detecting the presence or measuring the concentration of bacteria in a food product, comprising the steps of:
- providing a bacterial growth medium formulated for food testing, which comprises a first enzyme substrate for a phosphatase, a second enzyme substrate for a glycosidase, and a third enzyme substrate for a peptidase, wherein said first, second and third enzyme substrates cause or produce an identical type of detectable signal when hydrolyzed by their respective enzymes;
- inoculating said medium with said food product and incubating said medium under a condition suitable for bacterial growth for a period of time;
- and
- detecting or measuring the identical type of detectable signal as an indication of the presence or the concentration of bacteria in said food product;
- wherein said first enzyme substrate is selected from the group consisting of:
- a substrate for alkaline phosphatase, a substrate for acid phosphatase, and a substrate for pyrophosphatase;
- and
- said second enzyme substrate is selected from the group consisting of:
- a substrate for N-acetyl-β-D-galactosaminidase, a substrate for N-acetyl-β-D-glucosaminidase, a substrate for neuraminidase, a substrate for L-arabinopyranosidase, a substrate for β-D-fucosidase, a substrate for α-D-galactosidase, a substrate for β-D-galactosidase, a substrate for α-D-glucosidase, a substrate for β-D-glucosidase, a substrate for β-D-glucuronidase, a substrate for α-D-mannosidase, a substrate for β-D-xylosidase;
- and
- said third enzyme substrate is selected from the group consisting of:
- a substrate for peptidase, a substrate for (L or D amino acid)-aminopeptidase, a substrate for L-alanine aminopeptidase, a substrate for trypsin, and a substrate for chymotrypsin.
A bacterial growth medium formulated for food testing, comprising a first enzyme substrate for a phosphatase, a second enzyme substrate for a glycosidase, and a third enzyme substrate for a peptidase, wherein said first, second and third enzyme substrates cause or produce an identical type of detectable signal when hydrolyzed by their respective enzymes;
- wherein said first enzyme substrate comprises a substrate for alkaline phosphatase, said second enzyme substrate comprises a substrate for β-D-glucosidase and said third enzyme substrate comprises a substrate for L-alanine-aminopeptidase.
Dependencies are inferred from the claim text.