  Swimming bacteria in passive nematics in the form of lyotropic liquid
crystals are defined as a class of active matter known as living liquid crystal
in recent studies. It has also been shown that liquid crystal solutions are
promising candidates for trapping and detecting bacteria. Motivated by such
studies, we developed a mixed model of polar swimmers in active nematics. It is
found that such a mixture is highly sensitive to the presence of polar
swimmers, and shows the formation of large scale defects for relative swimmer
density of the order of 0.1%. Upon increasing the density of swimmers,
different phases of active nematics are found and it is observed that the
system shows two phase transitions. The first phase transition is a first order
transition from a quasi-long ranged ordered state to disordered active nematics
with larger scale defects. On further increasing density of swimmers, the
system transitions to a third phase, where swimmers form large, mutually
aligned clusters. These clusters sweep the whole system like a comb in
entangled hair and enforce local order in the the nematic rods. In the third
phase, nematic ordering increases with an increase in the density of polar
swimmers. However, due to the presence of small, unaligned stray clusters,
defects in the active nematic still remain.
