Heterocyst and akinete induction with altered pattern in Anabaena cylindrica, caused by neo-peptone

Abstract

Neo-peptone B119 (Difco) was found to have a significant effect on differentiation of heterocysts and akinetes in Anabaena cylindrica. On adding neopeptone (0.4 g/l) to exponential phase culture of A. cylindrica, the following effects were observed (i) increased heterocyst frequency with altered heterocyst spacing and presence of double and multiple heterocysts after 24 h in cultures grown on N-free medium, (ii) induction of regular pattern of heterocysts after 48 h, in culture grown on medium supplemented with NH4Cl, (iii) induction of pro-akinetes after 48 h in both N-free and ammonium-grown cultures. The higher concentrations of neo-peptone were lytic to A. cylindrica, and, its lytic and inductive effects could be decreased by acid hydrolysis or supplementation of NH4Cl. Gel-filtration of neo-peptone showed that the inductive as well as the lytic effect was associated with some active factor(s) with molecular weight between 10,000–20,000. The retention of the inductive effect on autoclavation but its loss on trypsin digestion suggested that active factor(s) may be heat stable polypeptide(s). The heterocyst induction by active factor(s) decreased and akinete induction increased with increasing culture age. The pro-akinetes induced during exponential phase divided before maturation, while those induced during late exponential phase, could achieve full maturity. Growth and nitrogenase activity was unaffected while there was an increase in mean cell length on treatment of A. cylindrica with active factor(s) from neo-peptone, indicating that the effect may be mediated through cell division process(es).