  To survive in harsh conditions, motile bacteria swim in complex environment
and respond to the surrounding flow. Here we develop a PDE model describing how
the flagella bending affects macroscopic properties of bacterial suspensions.
First, we show how the flagella bending contributes to the decrease of the
effective viscosity observed in dilute suspension. Our results do not impose
tumbling (random re-orientation) as it was done previously to explain the
viscosity reduction. Second, we demonstrate a possibility of bacterium escape
from the wall entrapment due to the self-induced buckling of flagella. Our
results shed light on the role of flexible bacterial flagella in interactions
of bacteria with shear flow and walls or obstacles.
