A retained viability index (RVI10) for evaluation of a cyanobacterial powder fertilizer

The preparation of a dry and powder fertilizer based on five nitrogen-fixing cyanobacterial strains is described. Tolypothrix tenuis and Nostoc muscorum resisted the drying and milling processes and showed a suitable recovering capacity in liquid media of different pH and salinity. Although a decrease in the cellular viability was observed with the storage time, the biomass of Nostoc muscorum retained viability for 16 months. The results were evaluated in terms of the retained viability index (RVI₁₀) specifically designed for the fertilizer material.