Description of Neochlorella semenenkoi gen. et. sp. nov. (Chlorophyta, Trebouxiophyceae), a Novel Chlorella-like Alga with High Biotechnological Potential

Abstract

Despite many publications about Chlorella-like algae, their reliable and accurate identification is still difficult due to their simplicity and high phenotypic plasticity. The molecular approach has revolutionized our understanding of the diversity of ’small green balls’, and a natural classification of this group is currently being developed. This work is aimed at providing a detailed study of the phylogenetic position, morphology, ultrastructure, and physiology of the biotechnologically remarkable Chlorella-like strain IPPAS C-1210. Based on the SSU–ITS1–5.8S–ITS2 phylogeny, genetic distances, and the presence of compensatory base changes (CBCs) in ITS1 and conserved regions of ITS2 secondary structures, we describe a new genus, Neochlorella, with IPPAS C-1210 as the authentic strain of the type species, N. semenenkoi gen. and sp. nov. In addition, we justify the reassignment of the strain C. thermophila ITBB HTA 1–65 into N. thermophila comb. nov. The distinctive ultrastructural and physiological traits of the new species are discussed.

Morphology and phylogenetic relationships of two Antarctic strains within the genera Carolibrandtia and Chlorella (Chlorellaceae, Trebouxiophyceae)

“…These genera include Actinastrum, Didymogenes, Hegewaldia, Heynigia, Hindakia, Meyerella, andMicractinium (Luo et al 2010, Pröschold et al 2010). Several Chlorella-like taxa belonging to the Chlorella clade have been identified in subsequent studies, including Carolibrantdia ciliaticola Nakada 2018, Hoshina et al 2018), Meyerella similis (Krivina et al 2022b), Meyerella krienitzii (Krivina et al 2023c), Micractinium inermum (Hoshina and Fujiwara 2013), M. singularis, M. simplicissimum, M. variabile (Chae et al 2019), M. tetrahymenae , M. kostikovii (Krivina et al 2022a), M. lacustre, M. thermotolerans (Krivina et al 2023a), Lewiniosphaera symbiontica , Neochlorella semenenkoi, and N. thermophila (Krivina et al 2023b). These species are distinguished by their phylogenetic positions and unique CBCs in the nuclear SSU and ITS2 rDNA genes (Luo et al 2006, Chae et al 2019, Krivina et al 2022a, 2022b, 2023a, 2023b, 2023c.…”

“…Since this proposal, each genus within the Chlorella clade appears to form a well-defined monophyletic clade (Luo et al 2010, Bock et al 2011, Chae et al 2019). However, recent phylogenetic studies have demonstrated that the polyphyly of the genus Chlorella (Krivina and Temraleeva 2020, Krivina et al 2022a, 2022b, 2023a, 2023b, 2023c. The differences in the phylogenetic analysis results were due to variations in the alignment methods used for the datasets.…”

Plants, Cells, Algae, and Cyanobacteria In Vitro and Cryobank Collections at the Institute of Plant Physiology, Russian Academy of Sciences—A Platform for Research and Production Center

“…Unicellular coccoid green microalgae with robust growth characteristics; thermotolerant, halotolerant, and alkaliphilic; accumulates lipids enriched with α-linolenic FA [202,203].…”

“…Additionally, their taxonomic position in the “marine Geitlerinema ” group was clarified [ 209 ]. Among green algae, a new species ( Micractinium thermotolerans Krivina et al) and a new genus and species ( Neochlorella semenenkoi ) were described [ 203 , 219 ].…”

“…The algae and cyanobacteria collection currently utilizes mid-term preservation at –70 °C to back up some strains from the active collection. Synechocystis mutant strains, model cyanobacteria C. subtropica IPPAS B-1603, Acaryochloris marina IPPAS B-1601, and type strains of novel cyanobacterial and green algal species [ 203 , 209 , 219 , 227 , 228 , 229 , 230 ] are preserved at −70 °C in a freezer with 10% dimethyl sulfoxide or 10% glycerol as cryoprotectors, as described by Iwamoto et al [ 231 ]. The strains C. subtropica IPPAS B-1603 and Spongiosarcinopsis terrestris IPPAS C-2041 were successfully recovered after several months of such storage, and A. marina IPPAS B-1601 was recovered after five years.…”