Cyanobacteria That Produce Megamolecules with Efficient Self-Orientations

Abstract

Liquid crystallization of structural megamolecules in plants is very significant in understanding of biopolymer self-orientation and developing plant-derived functional materials. Cyanobacterial megamolecules, sacrans (molecular weight: 1.6 × 107 g/mol), are polysaccharides derived from the extracellular matrix of Aphanothece sacrum, and are observed as self-orienting micro rods longer than 3 μm in dilute solution at c = 0.01 wt % by optical microscopes. Sacran chains form double helixes at c > 0.09 wt % and form huge domains (centimeter scale) of liquid crystals at c > 0.5 wt % which is quite low when compared to conventional liquid crystalline polysaccharides. Mesogenic helical chains of sacrans have extremely high aspect ratios of 1600 for highly persistent lengths of 32 μm.