Genome analyses of the genus Limnospira reveals the presence of two species, L. maxima and L. platensis, unable to produce microcystins

Spirulina is the common name for an edible cyanobacteria belonging to the genus Limnospira (previously Arthrospira and Spirulina), considered to be a food of interest with health benefits. Some confusion concerns the taxonomy of this genus with four species cited in the literature, but there is a consensus on the existence of two lineages interpreted as two species or two subspecies. Furthermore, although spirulina is considered edible, the species L. fusiformis is cited as potentially producing microcystins based on studies having detected cyanotoxins in some cultures of Kenyan strains. Taxonomic ambiguity based on the classification of Limnospira according to the rules of the ICN ('Botanical Code'), combined with suspected toxicity, constitutes a major issue for spirulina producers and food safety authorities. In a collection of seven spirulina cultivars, from different ecotypes, we were able to identify strains of the two lineages of Limnospira through genomic and morphological analyses. Illumina short-read sequencing of three non-axenic cultures and metagenomic binning resulted in high quality metagenome-assembled genomes (MAGs) of the cyanobacterium.