HETEROMORPHISM OF THE CYANOBACTERIUM NOSTOC SP, A MICROSYMBIONT OF THE BLASIA-PUSILLA MOSS

Morphology and ultrastructure of Nostoc sp., a cyanobiont of the Blasi a pusilla moss, were studied directly in the thallus cavity, as well a s after isolation and in the course of subsequent cultivation under la boratory conditions. This cyanobacterium displayed a high degree of he teromorphism manifested in its ability to form microcolonies, clusters , and filaments, and also to undergo differentiation into vegetative c ells, heterocysts, protoplasts, and microcells. It was supposed that, during the heterotrophic interstitial development in symbiosis with th e plant, Nostoc sp. cells undergo L-transformation. The important role of the mucous fibrillar matrix in the organization of clusters and in tracavitary microcolonies, as well as in the preservation of intact pr otoplasts of Nostoc sp., was revealed. It is concluded that the preser vation of the micropopulational organization of Nostoc sp. after its i solation into a culture provides prospects for studying the functions of protoplasts as components of the symbiotic cyanobacterial populatio n.