The rodlike microcrystal suspension prepared by sulfuric acid hydrolysis of bacterial cellulose was found to undergo spontaneous nematic phase separation after complete desalination. This phase separation was preceded by a birefringent glassy-like state for about 1 week. Addition of trace electrolyte (< 1 mM NaCl) caused remarkable changes in phase separation behavior; i.e., the separation was complete in 2 days and the anisotropic phase became chiral nematic. This phenomenon can be explained by the change in the effective particle shape, from cylindrical to the twisted rod as a result of screening of surface charge.