Survival of Escherichia coli on Polypropylene Surfaces Fouled with Organic Soil of Different Water Contents

概要

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Knowledge of survival behaviors of microorganisms on solid surfaces is important to assess and control the risk of cross contamination for food being processed on the surface. Here we report the survival behavior of Escherichia coli left on polypropylene coupons with or without nutritious soil subjected to drying at room temperature. When E. coli cells were left on the coupons with 0.85% saline solution, decrease in the viable cell number was observed in two stages, each of which followed the first order kinetics. The specific death rate was 0.21 h-1 initially and reduced to 0.11 h-1 after the water content reached 3.9 g-water/g-solid. When E. coli cells were left with Luria-Bertani broth, as a model soil, of different water contents, the viable cell number did not show a distinct decrease until the water content reached 3-4 g-water/g-solid. After the water content went down below the threshold, the specific death rate was roughly 0.1 h-1 though deviation was large especially at the final stage of drying. E. coli survived on the surface even after 2 days, and coexistence of nutrients enhanced the final level of viable cells.
日本食品工学会の論文