Microorganism locomotion: How speed-dependent nutrient absorption can enhance bacterial motility

M. DI SALVO; C.A. CONDAT; G.J. SIBONA

Angra dos Reis, Brasil

Workshop; Workshop on mathematical modeling of biophysical phenomenaM; 2009

Instituto Nacional de Matemática Pura e Aplicada

Marine bacteria often reach high swimming speeds, either to take advantage of evanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part of their energetic budget must be allocated to motion, it is reasonable to assume that some bacteria are able to increase their nutrient intake by increasing their speed v. We formulate a model that uses the concept of internal energy depot to investigate this hypothesis, postulating that the nutrient absorption rate is of the form q(v) = q0 +Av, with q0 and A being constants. We find the stationary solutions and analyze their stability and the influence of thermal noise. We also show that the mechanical efficiency of the molecular motors increases with A. The description of the motion is further clarified by the use of a Fokker-Planck formalism. Evaluations carried out using realistic parameter values indicate that the speed increase due to the enhanced nutrient absorption may be substantial.