Planktochlorella nurekis gen. et sp nov (Trebouxiophyceae, Chlorophyta), a novel coccoid green alga carrying significant biotechnological potential
Abstrakt
Phylogenetic position, morphology and ultrastructure were investigated for biotechnologically remarkable strain Chlorella vulgaris IFR C-111, utilized in various commercial applications. Molecular phylogenetic analyses based on the SSU and ITS rDNA data revealed that the strain IFR C-111 forms a distinct lineage within the Parachlorella-clade in Chlorellaceae.
We describe this organism as a new genus and species, Planktochlorella nurekis. Vegetative cells of this newly recognized species are spherical, possessing a single pot-shaped chloroplast with starch-covered pyrenoid.
Asexually it reproduces by the formation of 2-16(-32) autospores. Cell wall is composed of two layers, the outer layer containing extended microfibrillar material.
The fuzzy cell wall structure improves the buoyancy resulting in low sedimentation rate of P. nurekis. To resolve the phylogenetic position of Planktochlorella and its relationship to the closely related genera, nucleotide saturation present in the ITS rDNA data was reduced by four different approaches.
The resulting topologies pointed to the poor phylogenetic signal in generally utilized SSU and ITS rDNA data and the need of sequencing other molecular markers.