Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.
- American Society for Microbiology
- Modeling surface growth of escherichia coli on agar plates
MAS Introduces Filter Innovation
Our partner MAS has recently attracted attention for a range of technical innovations in extrusion and plastic recycling technology, including the co-rotational conical twin screw extruder and a waterless cleaning system for film flakes. This year, at the FAKUMA exhibition in Germany, MAS introduced further technical developments with a range of patent-protected continuous melt filtration systems available in three power levels for flow rates of from 300 to 2,000 kg/h. The MAS Filter Innovation The objective of...
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