Widespread formation of intracellular calcium carbonates by the bloom-forming cyanobacterium Microcystis.

The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis.

sp. nov., isolated from waterways.

Through this study, we established the taxonomic status of seven strains belonging to the genus (A477-S1-J17, A398-S21-F17, A535-S3-A17, A411-S4-F17, A113-S21-F16, FL63-S17 and FL60-S17) collected from four different river streams and an artificial lake in south-east France between 2016 and 2017. Ecological surveys in rivers and lakes pointed out different repartition of strains belonging to this clade compared to the closest species, . The main phenotypic difference observed between these strains and the type strain was strongly impaired growth with rhamnose as the sole carbon source.