A Comparison of Techniques for Recovering Bacillus subtilis Spores from Inoculated Meat Substrates

Blender maceration, insonation, rotary shaker washing, and stomacher processing were initially evaluated as mechanical methods for bacterial spore recovery from inoculated beef substrates. Ionic dispersants (Daxads) and wetting agents were also evaluated for augmentation of spore recovery when used as sample diluents and processing vehicles. Spore recovery rates were shown to be affected by, the spore inoculum titer, mechanical processing method, and diluent type (p=0.001). These experimental factors also demonstrated significant interactions affecting spore recovery. The best initial combination tested (blender‐Daxad) only produced a recovery rate of 66%, with large variances in sample means when tested over a wide range of inoculum levels. This result prompted a posteriori test using a tissue homogenizer, which produced higher recovery rates than the blender, with stable variance over a wide range of inoculum levels.