Akinete differentiation in phototrophic, photoheterotrophic and chemoheterotrophic conditions inAnabaena torulosa

Abstract

Akinete differentiation inAnabaena torulosa occurred under phototrophic, photoheterotrophic and chemoheterotrophic conditions at the expense of fructose in nitrate-free and nitrate media. Maximum frequency of akinetes was recorded in nitrate-free cultures in photoheterotrophic condition followed by chemoheterotrophic condition. The activity of glucose-6-phosphate dehydrogenase (GPDase) and the levels of glycogen exhibited a correlation with the presence and absence of nitrate and maximum activity was detected in photoheterotrophic condition at the maturation phase. The cells in nitrate-free medium exhibited enhanced levels of GPDase, nitrogen fixation and low levels of glycogen in the presence of fructose. A lowering of GPDase activity in nitrate grown cells was found to be associated with the accumulation of glycogen. The results presented here further suggest that a critical balance of the C:N ratio triggers akinete differentiation.