Common nitrogen control of caesium uptake, caesium toxicity and ammonium (methylammonium) uptake in the cyanobacterium Nostoc muscorum

Abstract

Studies were carried out to examine the role of ammonium transport activity in the control of caesium uptake and toxicity in Nostoc muscorum. The results showed a definite specific role of the ammonium-repressible/derepressible ammonium transport system of the cyanobacterium in caesium uptake, accumulation and toxicity. Furthermore, the results showed that N. muscorum can acquire resistance against diazotrophically-associated caesium toxicity when supplied with ammonium as a nitrogen source. In addition, alternatively, a mutant strain was Cs-resistant in the absence of any effect on NH4+-transport, suggesting that Cs+ resistance may be determined at more than one cellular site. © 1994.