e., dilution) in both additive terms. The fit will be satisfactory, but the parametric estimates thus obtained will only represent a combination of the responses due to the correlation of increasing doses of the two effectors. In the case of two effectors with effects of opposite sign, the

profile will show features of hormesis, and the appropriate model will be subtractive (SHP099 ic50 Figure 9S). A similar analysis is applicable to the case of a single effector against a population with a bimodal distribution of sensitivity. On the other hand, if the number of effectors (or the number of subpopulations with different sensitivity to a single effector) increases, the overlap of the different responses tends to smooth the waves of the profile. Under these conditions, such waves are easily EPZ5676 cost BI-2536 absorbed by the experimental error, and the result can be fitted again to a

simple sigmoidal model. Acknowledgements We wish to thank to Ana Durán and Margarita Nogueira for their excellent technical assistance. The English usage in the manuscript has been completely revised and edited by Elsevier language editing services. Electronic supplementary material Additional file 1: Figure A1: Effect of nisin on L. mesenteroides growth at three temperatures. In this Figure the effect of nisin on L. mesenteroides growth, measured as absorbances at 700 nm, is shown. The experimental data were done at three temperatures (23°C, 30°C and 37°C). The concentrations of nisin tested were (in mg/l): Control without nisin (white circle); 0.98 (black triangle); 1.95 (black square); 3.90 (black rhombus); 7.80 (black star); 15.60 (white square); 31.25 (white down-triangle); 62.50 (white triangle); 125 (white rhombus); 250 next (black circle); 500 (black down-triangle). (DOC 37 KB) References 1.

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