Growth and Adhesion of Pseudomonas fluorescens in a Batch Culture: A Kinetic Analysis of the Action of Extracellular Antiadhesins

Abstract

This work tests 6 hypothetical models simulating the growth, respiration, and adhesion of cells to the walls of the cultivation flask. All the models postulate the synthesis of antiadhesins (AAs), i.e., extracellular metabolites decreasing the degree of cell adhesion. The models have the following distinguishing features: (model 1) the blocking of sorption centers on the glass walls by antiadhesins (the competitive inhibition of adhesion); (model 2) the noncompetitive inhibition of adhesion; (model 3) the accelerated release of bound cells; (model 4) a combination of models 1 and 3; (model 5) a combination of models 1 and 3 with a delay; (model 6) a combined action of two AAs, one of which, AA₁, inhibits cell adhesion, and the other, AA₂ (its synthesis is induced when the concentration of AA₁ reaches a threshold level), stimulates the detachment of bound cells. Model 6 fits the relevant experimental data best. The delay effect is relatively small. The sigmoid character of the curve showing cell adhesion as a function of the antiadhesin concentration implies the existence of a strong cooperative effect in the adhesion inhibition. The models proposed satisfactorily simulate the growth, respiration, and adhesion of cells and AA synthesis in a batch bacterial culture grown either in a fresh nutrient medium or in the medium supplemented with the filtrate of a mature culture of the same species.