Isolation and characterization of a chlorate-resistant mutant of Spirulina platensis

Three chlorate-resistant mutants of the cyanobacterium Spirulina platensis were obtained by UV irradiation and one of them (LL1) was further characterized for its nutritional requirements and for the capacity to reduce nitrate in vivo and in vitro. The results indicate that mutation leading to chlorate resistance is not due to inactivation of nitrate reductase but is most likely due to the loss of permeability to chlorate and nitrate. The other two mutants seem to have properties similar to those of LL1.