Alteration of Heterocyst Pattern and Akinete Formation in Anabaena Cylindrica Produced by Neopeptone

Abstract

Anabaena cylindrica does not form heterocysts on N-supplemented medium, but on transfer to N-free medium, proheterocysts appear at regular intervals in filaments after 6 hrs of incubation. These proheterocysts, develop into mature hetero cysts after about 1U hrs of incubation. Akinete formation occurs during the late exponential phase of both N-free and N-supplemented cultures and akinetes are always formed adjacent to the heterocyst in N-free cultures. On adding Neo-peptone B119 (Difco) at concentration 0.4 g/l to lag phase cultures of A. cylindrica, following effects were observed after 40 hrs incubation: (i) increased heterocyst frequency with altered heterocyst spacing and presence of double and multiple heterocysts in cultures grown cultures on N-free medium, (ii) induction of regular pattern of heterocysts in ammonia-grown cultures, (iii) induction of akinete formation both adjacent and non adjacent to heterocysts in both N-free and ammonia-grown cultures.