Spoilage characteristics of Brochothrix thermosphacta and campestris in chilled vacuum packaged lamb, and their detection and identification by real time PCR

• B. Campestris is able to spoil vacuum packaged lamb.
• Development and validation of a Brochothrix specific Real time PCR.
• Development of a standard PCR assay for the differentiation of Brochothrix species.

The spoilage potential of Brochothrix campestris and Brochothrix thermosphacta was investigated in vacuum-packed lamb. Striploins (n = 338) were inoculated and stored for twelve weeks at temperatures − 1.5, 0, 2 and 7 °C. Growth around 5–6 log10 CFU/cm2 was recorded after six weeks at 0, 2 and 7 °C, and ~ 3 log10 CFU/cm2 after nine weeks at − 1.5 °C. B. campestris was shown to cause spoilage by nine weeks at temperatures above 0 °C by the presence of green drip and unacceptable odours. Molecular based assays for the detection and differentiation of B. thermosphacta and B. campestris were developed and validated. A TaqMan assay was designed to target a unique single-nucleotide polymorphism in the Brochothrix 16 s rRNA gene with a sensitivity of < 7 CFU per reaction. Secondly a specific PCR was designed for B. campestris targeting the structural genes, brcA and brcB. These testing regimes offer a rapid and cost effective method for the detection and screening of Brochothrix species in meat products and processing environments.