Growth of Listeria monocytogenes in a multispecies biofilm formed in a humid environment with soluble protein

by 1974- Birt, Dawn M.

The primary objective of this research project is to determine the ability of L. monocytogenes to grow as part of a mixed species biofilm in the presence of condensation and protein soils. The secondary objective is to devise a laboratory scale model system to simulate biofilms on surfaces that are often subjected to food soils as well as condensation in food processing areas held at 12 ºC. L. monocytogenes maintained greater populations in biofilms exposed to protein soils (from 0.1 to 1.3 Log CFU/cm 2 over a 5 week time period), which simulates an inadequately cleaned surface. This supports our hypothesis that the presence of protein soil will affect the growth of L. monocytogenes. High rinse counts (10^5 to 10^6) indicate the ability of these biofilms to act as a reservoir for L. monocytogenes, which can then contaminate product as well as food contact surfaces through dripping condensation.