Marinichlorella Kaistiae gen. et sp nov (Trebouxiophyceae, Chlorophyta) based on polyphasic taxonomy

We describe three coccoid green algal strains belonging to a new genus and species, Marinichlorella kaistiae Z. Aslam, W. Shin, M. K. Kim, W.-T. Im et S.-T. Lee, in seawater samples from the South Sea of Korea. These strains were maintained at 25 degrees C-30 degrees C under a 12:12 light:dark (L:D) photoregime in an ASN-III medium at a pH of 7.5. These strains were tolerant of high salinity (7.5% NaCl) (w/v) and temperature (40 degrees C). Molecular phylogenetic analyses using 18S rRNA gene sequence data resolved these organisms to a clade separate from green coccoid algae with similar morphology. The DNA-DNA hybridization results demonstrated very low relatedness of these organisms to phylogenetically related species of the genera Chlorella and Parachlorella. The molar guanine + cytosine content (G + C mol%) of the genomic DNA of these organisms ranged from 64.7 to 69.1 mol%. Based on molecular phylogeny, DNA-DNA hybridization, and other morphological studies, we propose a new taxon, Marinichlorella kaistiae, to describe these strains and classify them in the family Chlorellaceae. The type strain is KAS007(T) (= KCTC AG10303(T) = IAM C-620(T)).