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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #107123
Title: MONITORING THE MICROBIAL CONTAMINATION OF BEEF CARCASS TISSUE WITH A RAPID CHROMOGENIC LIMULUS AMOEBOCYTE LYSATE ENDPOINT ASSAY

Author
item Siragusa, Gregory
item Kang, Dong Hyun
item CUTTER, CATHERINE - FORMER ARS EMPLOYEE

Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: A modified version of a commercially available color test for fecal bacteria was validated as a means of rapidly gauging levels of beef carcass microbial contamination. The assay, known as the Limulus Amoebocyte Lysate (LAL) test, requires 16 minutes to perform and functions on carcass tissues that are either fresh from the slaughter floor (approximately 30 deg C to 37 deg C) or that have been chilled (approximately 4 deg C). This assay predicted non-specific microbial load (both non-pathogenic and potentially pathogenic aerobic bacteria) of a beef carcass down to approximately 100 per square centimeter at a high level of agreement with the standard 24 hour plate count procedure. This assay requires no instrumentation other than a 37 deg C incubator and is applicable to processors wishing to rapidly assess microbial levels of carcasses during processing.

Technical Abstract: A chromogenic Limulus amoebocyte lysate (LAL) endpoint assay was found to be an accurate and rapid means to gauge levels of beef carcass microbial contamination within 10 min. The assay demonstrated a high correlation with the total mesophilic bacterial and coliform surface populations from inoculated beef carcass surface tissues. This assay was tested on a set of actual beef carcass surface samples (n = 121) demonstrating the utility of the chromogenic LAL test as a means to monitor carcass microbial contamination in a near real time fashion. Classifying the chromogenic LAL results into four contamination groups was found to be a sound means of utilizing the resultant chromogenic LAL data for detecting carcasses with high levels of microbial contamination. For beef carcass testing, this assay can be used with no instrumentation other than the required 37 deg C incubator and, as an option, a microplate reader.