  Bacteria living on surfaces use different types of motility mechanisms to
move on the surface in search of food or to form micro-colonies. Twitching is
one such form of motility employed by bacteria such as N. gonorrhoeae, in which
the polymeric extensions known as type IV pili mediate its movement. Pili
extending from cell body adheres to the surface and pulls the bacteria by
retraction. The bacterial movement is decided by the two-dimensional tug-of-war
between the pili attached to the surface. Natural surfaces in which these
micro-crawlers dwell are generally spatially inhomogeneous and have varying
surface properties. Their motility is known to be affected by the topography of
the surfaces. Therefore, it is possible to control bacterial movement by
designing structured surfaces which can be potentially utilized for controlling
biofilm architecture. In this paper, we numerically investigate the twitching
motility in a two-dimensional corrugated channel. The bacterial movement is
simulated by two different models: (a) a detailed tug-of-war model which
extensively describe the twitching motility of bacteria assisted by pili and
(b) a coarse-grained run-and-tumble model which depicts the motion of
wide-ranging self-propelled particles. The simulation of bacterial motion
through asymmetric corrugated channels using the above models show
rectification. The bacterial transport depends on the geometric parameters of
the channel and inherent system parameters such as persistence length and
self-propelled velocity. In particular, the variation of the particle current
with the geometric parameters of the micro-channels show that one can optimize
the particle current for specific values of these parameters.
