COLONIZATION OF BEEF MUSCLE SURFACES BY PSEUDOMONAS-FLUORESCENS AND PSEUDOMONAS-FRAGI

Attached and unattached cell densities were determined for Pseudomonas fluorescens and Pseudomonas fragi growing on the surface of beef muscle stored at 4 and 25°C, in presence of NaCl, KCl, and CaCl2. A mechanical rinsing procedure was developed for this purpose. Both species colonized the surface at both temperatures and were enhanced at low (4°C) temperature. Attached cells represented up to 90% of the total until a density of 105‐106 CFU cm−2 was reached. At that point, a proportion of attached cells to unattached cells declined but colonization of the surface continued. In presence of CaCl2, ratios of attached to unattached cells did not decline, suggesting a significant role for the calcium ion in colonization. Ability to colonize meat surfaces may be a significant competitive advantage for meat spoilage bacteria such as Pseudomonas fragi and Pseudomonas fluorescens. Copyright © 1990, Wiley Blackwell. All rights reserved