Baeocytes and pseudofilamentous stages of Pleurocapsa concharum Hansgirg (Cyanobacteria, Pleurocapsales) in culture
Tandon, Richa; Kesarwani, Sarika; Tiwari, G.L.
Pleurocapsa concharum Hansgirg was isolated and maintained in culture to observe various growth stages under controlled conditions. Observations of growth in BG-11 medium showed no clear separation between the phases of binary fission to form macrocytes and multiple fissions to form baeocytes. So long as favourable conditions and sufficient nutrients remained, divisions continued to take place forming small baeocytes. In old cultures, colonies turn brownish and were covered by sheaths, later individual baeocytes grew and enlarged in situ and divided to form 2–4–8 celled colonies. Further, individual cells may also become enveloped to form Chroococcus-like stages. When old and perennating colonies were transferred to fresh medium they became blue-green in colour and formed new clusters of colonies. In most of the observations based on material collected from natural habitats and culture conditions, the organism could be identified as Myxosarcina because pseudofilamentous stages were not seen in nature and for a long time not even in culture. During seven years of observation, pseudoheterotrichous or pseudofilamentous stages were only observed twice during the revival of senescent cultures. However these stages could not be reproduced even after repetition in the same growth conditions. It is concluded that pseudofilamentous stages are extremely rare usually found in senescent cultures and may be related to attachment or nutrient availability.