Manganese as Substitute for Magnesium During Magnesium-limited Growth of the Cyanobacterium Anacystis nidulans

SUMMARY: An apparent inhibition of cell division in the cyanobacterium Anacystis nidulans, caused by low Mg2+ concentrations, was abolished by increasing the medium Mn2+ concentration. Thus the mean cell volume of this organism growing in a Mg2+-limited chemostat culture decreased from an average of 1.3 to 0.4 μm3 following an increase in the reservoir Mn2+ concentration from 9.5 to 15 μM. This increase in Mn2+ had no effect on the steady-state biomass concentration, while a further elevation of the Mn2+ concentration lowered the biomass concentration, seemingly by making Mg2+ less available to the organism. The cellular Mn2+ concentration increased, while cellular Mg2+ was unaltered, following an increase in the medium Mn2+ concentration.