  We investigate the conformations of DNA-like stiff chains, characterized by
contour length ($L$) and persistence length ($l_p$), in a variety of crowded
environments containing mono disperse soft spherical (SS) and spherocylindrical
(SC) particles, mixture of SS and SC, and a milieu mimicking the composition of
proteins in $E. coli.$ cytoplasm. The stiff chain, whose size modestly
increases in SS crowders up to $\phi\approx 0.1$, is considerably more compact
at low volume fractions ($\phi \leq 0.2$) in monodisperse SC particles than in
a medium containing SS particles. A 1:1 mixture of SS and SC crowders induces
greater chain compaction than the pure SS or SC crowders at the same $\phi$
with the effect being highly non-additive. We also discover a counter-intuitive
result that polydisperse crowding environment, mimicking the composition of a
cell lysate, swells the DNA-like polymer, which is in stark contrast to the
size reduction of flexible polymer in the same milieu. Trapping of the stiff
chain in a fluctuating tube-like environment created by large-sized crowders
explains the dramatic increase in size and persistence length of the stiff
chain. In the polydisperse medium, mimicking the cellular environment, the size
of the DNA (or related RNA) is determined by $L/l_p$. At low $L/l_p$ the size
of the polymer is unaffected whereas there is a dramatic swelling at
intermediate value of $L/l_p$. We use these results to provide insights into
recent experiments on crowding effects on RNA, and also make testable
predictions.
