Comprehensive Investigation of a Toxic Microcystis sp. (Cyanobacteria) Collected from Snow Lake (New Mexico, USA).

Abstract The toxin producing cyanobacterium Microcystis sp. was collected in the mid October 2020 from the shallow waters of Snow Lake (New Mexico, USA). This species caused a visible bloom consisting of the pale green irregular macro colonies. Mass spectral analysis of the biomass revealed the presence of 4 derivatives of microcystin in that bloom: MC-LR (in the water and biomass), MC-RR (in biomass), MC-LY (in biomass), and MC-YR (in biomass).Next-generation sequencing allowed the retrieval of two Microcystis sequences in the bloom; which are molecular benchmarks for toxic Microcystis that may be used in future monitoring studies. Light microscopy provided evidence for the taxonomic affiliation of the found morphotype as Microcystis flos-aquae (Wittrock) Kirchner. However, molecular sequencing and the present situation in cyanobacterial taxonomy prevented affiliation of our morphotype to Microcystis flos-aquae, justifying following name – Microcystis sp. Confocal microscopy was used to determine the distribution of the cell content utilizing 3D stereo imaging. Emission spectra analysis identified the pigment composition and pigment distribution within the cells. SEM revealed 3D arrangement of the cells in the colonies, texture of the surface of the cells (perhaps dehydrated collapsed polysaccharides), F-layer and pili-like structures. Additionally, SEM/EDS analysis confirmed the F-layer using elemental composition analysis, which showed sulfur in the F-layer – typical element for that structure. Through the use of AFM, we analyzed the texture of the cell's surface and confirmed pili-like structures.