A simple and low-cost resazurin assay for vitality assessment across species

Working with biological organisms requires knowledge about the state of their viability and vitality to ascertain efficient processes. The phenoxazine dye resazurin is routinely used for viability assessment of many different species. Here, a novel use for resazurin as an indicator for vitality assessment across several species is proposed. Different amounts of biomass as well as mixtures of live/dead biomass were investigated for their capabilities of metabolizing resazurin and monitored over time. Increasing (live) biomass was found to increase reaction rate in a linear fashion, giving information about the cells' vitality. In an application example, stored suspension cultures of Sporosarcina pasteurii were found to decrease in viability over time, while urease activity decreased as well. For the first time, the assessment of vitality by one technique was demonstrated for several species in parallel.