Enhancement of microbial motility due to speed-dependent nutrient absorption

Abstract

Marine microorganisms often reach high swimming speeds, either to take advantage ofevanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part oftheir energetic budget must be allocated to motion, it is reasonable to assume that somefast-swimming microorganisms may increase their nutrient intake by increasing their speedv.We formulate a model to investigate this hypothesis and its consequences, finding thesteady-state solutions and analyzing their stability. Surprisingly, we find that even modestincreases in nutrient absorption may lead to a significant increase of the microbial speed. Infact, evaluations obtained using realistic parameter values for bacteria indicate that the speedincrease due to the enhanced nutrient absorption may be quite large.