The description of Haematococcus privus sp. nov. (Chlorophyceae, Chlamydomonadales) from North America

Abstract

An enormous body of research is focused on finding ways to commercialize carotenoids produced by the unicellular green alga, Haematococcus, often without the benefit of a sound phylogenetic assessment. Evidence of cryptic diversity in the genus means that comparing results of pigment studies may be confounded by the absence of a phylogenetic framework. Moreover, previous work has identified unnamed strains that are likely candidates for species status. We reconstructed the phylogeny of an expanded sampling of Haematococcus isolates utilizing data from nuclear ribosomal markers (18S rRNA gene, 26S rRNA gene, internal transcribed spacer [ITS]-1, 5.8S rRNA gene, and ITS-2) and the rbcL gene. In addition, we gathered morphological, ultrastructural and pigment data from key isolates of Haematococcus. Our expanded data and taxon sampling support the concept of a new species, H. privus, found exclusively in North America. Despite overlap in numerous morphological traits, results indicate that ratios of protoplast length to width and akinete diameter may be useful for discriminating Haematococcus lineages. High growth rate and robust astaxanthin yield indicate that H. rubicundus (SAG 34-1c) is worthy of additional scrutiny as a pigment source. With the description of H. privus, the evidence supports the existence of at least five, species-level lineages in the genus. Our phylogenetic assessment provides the tools to frame future pigment investigations of Haematococcus in an updated evolutionary context. In addition, our investigation highlighted open questions regarding polyploidy and sexuality in Haematococcus which demonstrate that much remains to be discovered about this green flagellate.

Effects of aeration and centrifugation conditions on omega-3 fatty acid production by the mixotrophic dinoflagellate Gymnodinium smaydae in a semi-continuous cultivation system on a pilot scale

“…We measured the densities of G. smaydae and Heterocapsa rotundata as prey in a 100-L semi-continuous cultivation system under no aeration and continuous aeration conditions daily for 9 days. Furthermore, to determine optimal harvest conditions through centrifugation, we examined the harvesting efficiency and dry weights of fatty acids in G. smaydae + H. rotundata cells at different rotational speeds and at different flow rates of the pump frequently predominant in plankton assemblages (Jeong et al 2021, Kang et al 2023, and they produce useful biological materials including fatty acids, amino acids, functional pigments, antioxidants, and toxins (Hwang and Lu 2000, Jang et al 2017, Lim et al 2018, Wang et al 2022, Buchheim et al 2023. Therefore, marine microalgae have potential applications with regard to bioenergy resources, animal feed, human foods, health supplements, and pharmaceuticals (Atalah et al 2007, Fuentes-Grünewald et al 2009, Manirafasha et al 2016, Lim et al 2018.…”

Comparative Metabolomic and Network Analysis of the Hyperaccumulation of Astaxanthin in <em>Haematococcus pluvialis</em> under the Different Stress Conditions

“…Haematococcus pluvialis is a type of unicellular green algae, which is distributed in variable freshwater, saline and semi-saline habitats worldwide [5][6][7][8][9]. Furthermore, H. pluvialis is widely recognized as one of the best natural sources of astaxanthin.…”