Enhancement of Microbial Motility due to Speed-Dependent Absorption

MARIO E. DI SALVO AND C. A. CONDAT

Buenos Aires

Workshop; Giambiagi Winter School 2013; 2013

UBA

Marine microorganisms 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 fast-swimming microorganisms may increase their nutrient intake by increasing their speed v. We formulate a model to investigate this hypothesis and its consequences. We postulate that the nutrient absorption rate is of the form q(v) = q0 + Av, with q0 and A being constants. We find the steady state solutions and analyze their stability. Evaluations obtained using realistic parameter values indicate that the speed increase due to the enhanced nutrient absorption may be substantial. We also investigate how the microorganism’s dynamics can be influenced by the speed dependence of the transformation rate from the stored energy to kinetic energy.