The Effect of Ammonium on Viability, Growth and Pigment Composition of Fischerella sp. (Cyanophyta)

摘要

We studied the viability, growth and pigmentation of Fischerella sp., in the presence of ammonium. Maximum growth rate was seen in the absence of ammonium. Biomass in nitrogen (N) free medium and ammonium 1 and 2 mM were in decreasing order of preference. NH/ 2 mM was drastically toxic for this strain. The highest chlorophyll concentration was detected in N-free medium. Photosynthesis varied in same way as chlorophyll. Phycobiliproteins, phycocyanin and phycoerythrin had the highest rate in N-free medium. The highest light-saturated photosynthetic rate and also steepest initial slope clearly belonged to N-free medium. With respect to nitrogenase activity, combined nitrogen source inhibited it, regardless the concentrations used. Our results indicated that higher concentration of ammonium has an inhibitory effect on growth and metabolism of Fischerella sp. and also this strain is a potent diazotrophic species.