A Polyphasic Characterisation of Tetradesmus almeriensis sp. nov. (Chlorophyta: Scenedesmaceae)

Abstract

The microalga Tetradesmus almeriensis, previously known as Scenedesmus almeriensis, has been isolated and cultivated as a highly productive, fast-growing strain known as a natural source of different products of commercial interest, including bioactive compounds such as lutein. This strain produces up to 40 g·m−2·day−1 of lutein under optimal conditions and is highly recommendable for outdoor production in temperate and warm climates, showing maximal performance at temperatures up to 35 °C with no photo-inhibition taking place with irradiances greater than 1000 μE·m−2·s−1. Morphological and molecular data allow its assignment to the Chlorophycean genus Tetradesmus. The new species can be distinguished from similar Tetradesmus taxa due to its unique combination of features that are seen under light microscopy. We present herein a robust and comprehensive phylogenetic analysis of T. almeriensis, together with several additional Scenedesmaceae species, using a combination of maximum likelihood and Bayesian approaches. Our results confirm T. almeriensis as a distinct species consistently clustering with other Scenedesmaceae.

Taxonomic reinvestigation of the genus Tetradesmus (Scenedesmaceae; Sphaeropleales) based on morphological characteristics and chloroplast genomes

“…The oval or ellipsoidal cells are typical traits of the genus Scenedesmus (Tsarenko and John, 2011). Furthermore, the phylogenetic analysis using rbcL and ITS sequences revealed that T. almeriensis shows a monophyletic relationship with Scenedesmus species (Turiel et al, 2021). We confirmed the same phylogenetic relationship using ITS1-5.8S-ITS2, rbcL, and tufA genes (Supplementary Figure 6); hence, we suggest transferring T. almeriensis CCAP 276/24 to the genus Scenedesmus as follows.…”

“…For instance, T . almeriensis Turiel, Garrido-Cardenas, Gómez-Serrano, Acién, Carretero-Paulet & S.Blanco (the reference strain CCAP 276/24), which was reported as a new species in the genus Tetradesmus , displays oval or ellipsoidal cells without acuminate cell poles rather than spindle cells ( Turiel et al., 2021 ). The oval or ellipsoidal cells are typical traits of the genus Scenedesmus ( Tsarenko and John, 2011 ).…”

“…Furthermore, the phylogenetic analysis using rbcL and ITS sequences revealed that T . almeriensis shows a monophyletic relationship with Scenedesmus species ( Turiel et al., 2021 ). We confirmed the same phylogenetic relationship using ITS1-5.8S-ITS2, rbc L, and tuf A genes ( Supplementary Figure 6 ); hence, we suggest transferring T .…”

“…Although we reinvestigated the taxonomy of Tetradesmus species based on morphological characteristics and chloroplast genomes, we recognized that potential taxonomic issues in several reports remain, as described in the following cases. For instance, T. almeriensis Turiel, Garrido-Cardenas, Gómez-Serrano, Acień, Carretero-Paulet & S.Blanco (the reference strain CCAP 276/24), which was reported as a new species in the genus Tetradesmus, displays oval or ellipsoidal cells without acuminate cell poles rather than spindle cells (Turiel et al, 2021). The oval or ellipsoidal cells are typical traits of the genus Scenedesmus (Tsarenko and John, 2011).…”