Noise-enhanced mechanical efficiency in microorganism transport

Brownian forces have a nonnegligible effect on the motion of small microorganisms (sizes of the order of the μ or smaller). Starting from the model for the motion of Brownian objects with internal energy depots recently proposed by Schweitzer et al. (Phys. Rev. Lett. 80 (1998) 5044) (SET), we show that external fluctuations can increase the mechanical efficiency of a microorganism's propulsion system. Our analytical results and Monte-Carlo simulations suggest that, under certain circumstances, microorganisms can take advantage of Brownian forces to search more efficiently for a favorable environment. Other dynamical properties of the model are also examined.