Research

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25 pages, 18135 KiB

Open AccessArticle

Discovery of Cyanobacteria Associated with Cycads and Description of Three Novel Species in Desmonostoc (Nostocaceae)

by Melissa H. Pecundo, Tao Chen, Thomas Edison E. dela Cruz, M. Patrick Griffith, Zhangli Hu, Huirong Chen and Nan Li

Diversity 2023, 15(11), 1132; https://doi.org/10.3390/d15111132 - 06 Nov 2023

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Abstract

Heterocyte-forming cyanobacteria form symbiotic relationships with several lineages of plants. Here, twenty (20) strains of endosymbiotic cyanobacteria (cyanobionts) with Nostoc-like morphologies were isolated from the highly specialized coralloid roots of five host species in Cycadales—Cycas debaoensis, C. fairylakea, C. [...] Read more.

Heterocyte-forming cyanobacteria form symbiotic relationships with several lineages of plants. Here, twenty (20) strains of endosymbiotic cyanobacteria (cyanobionts) with Nostoc-like morphologies were isolated from the highly specialized coralloid roots of five host species in Cycadales—Cycas debaoensis, C. fairylakea, C. elongata, Ceratozamia robusta, and Macrozamia moorei. Molecular phylogeny based on the 16S rRNA gene placed these strains into seven different taxa within the Nostocaceae, specifically under the genera Desmonostoc and Dendronalium. The percent dissimilarity and unique patterns in the secondary structures of the D1-D1′, Box-B, V2, and V3 helices, which were based on the 16S–23S rRNA internal transcribed spacer (ITS) regions, supported three distinct species in Desmonostoc. These three morphologically distinct novel species are described in this report: Desmonostoc debaoense sp. nov., Desmonostoc meilinense sp. nov., and Desmonostoc xianhuense sp. nov. Other investigated strains were phylogenetically identified as members of the recently discovered genus Dendronalium and represent the first report of association of that genus with cycads. Our findings suggest that the order Cycadales hosts diverse species of cyanobionts in their coralloid roots and that many potential unreported or novel taxa are present in cycads occurring in their natural habitat and await discovery. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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29 pages, 8314 KiB

Open AccessEditor’s ChoiceArticle

Hot Is Rich—An Enormous Diversity of Simple Trichal Cyanobacteria from Yellowstone Hot Springs

by Jan Kaštovský, Jeffrey R. Johansen, Radka Hauerová and Mildred U. Akagha

Diversity 2023, 15(9), 975; https://doi.org/10.3390/d15090975 - 28 Aug 2023

Cited by 3 | Viewed by 1154

Abstract

In 2019, cyanobacterial samples were collected from thermal sites in Yellowstone National Park. In this paper, we discuss the considerable richness of representatives of simple filamentous cyanobacteria. Using a polyphasic approach, one new genus, Copelandiella, with two species (C. yellowstonensis and [...] Read more.

In 2019, cyanobacterial samples were collected from thermal sites in Yellowstone National Park. In this paper, we discuss the considerable richness of representatives of simple filamentous cyanobacteria. Using a polyphasic approach, one new genus, Copelandiella, with two species (C. yellowstonensis and C. thermalis) and eight additional new species Albertania prattii, K. anagnostidisii, Kovacikia brockii, Leptolyngbya tildenae, L. vaporiphila, Nodosilinea calida, N. igneolacustris, and Oculatella castenholzii were described. At the same time, by analyzing our new molecular data, we concluded that other genera of trichal cyanobacteria can be merged with existing genera: species within the genus Plectolyngbya are herein transferred to Leptolyngbya, and if some nomenclatural issues are resolved, species within the genus Leptothermofonsia will be subsequently transferred to the genus Kovacikia, an earlier synonym. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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32 pages, 11683 KiB

Open AccessArticle

Morphological and Molecular Evaluation of Pseudanabaena epilithica sp. nov. and P. suomiensis sp. nov. (Pseudanabaenaceae, Cyanobacteria) from Finland

by Maria Christodoulou, Matti Wahlsten and Kaarina Sivonen

Diversity 2023, 15(8), 909; https://doi.org/10.3390/d15080909 - 01 Aug 2023

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Abstract

Cyanobacteria represent a cosmopolitan group of oxyphototrophic bacteria. Although free-living cyanobacteria thriving in aquatic habitats as well as cyanobacteria in terrestrial symbiotic systems (lichens) have been extensively studied in Finland, the diversity of terrestrial rock-inhabiting cyanobacteria is overlooked. As part of an ongoing [...] Read more.

Cyanobacteria represent a cosmopolitan group of oxyphototrophic bacteria. Although free-living cyanobacteria thriving in aquatic habitats as well as cyanobacteria in terrestrial symbiotic systems (lichens) have been extensively studied in Finland, the diversity of terrestrial rock-inhabiting cyanobacteria is overlooked. As part of an ongoing effort to study terrestrial epilithic cyanobacteria from Finland, we isolated two Pseudanabaena-like cyanobacterial strains and characterized them using a polyphasic approach. Although the two strains were firmly placed within the Pseudanabaena clade in the 16S rRNA phylogenetic analyses, relationships among species were better resolved when phylogenetic analyses were based on a concatenate alignment of 16S rRNA gene and 16S–23S Internal Transcribed Spacer (ITS) region. In addition, 16S–23S ITS percent dissimilarity proved to be more useful for species discrimination in Pseudanabaena compared to secondary structures of conserved 16S–23S ITS domains (D1–D1′, box B, V2 and V3 helices). Considering morphological, molecular and ecological information, we describe P. epilithica sp. nov. and P. suomiensis sp. nov. under the provisions of the International Code of Nomenclature for Algae, Fungi and Plants. Neither toxins nor antimicrobial metabolites were detected during LC-MS analysis or antimicrobial susceptibility testing, respectively. Lastly, our phylogenetic analyses revealed that many Pseudanabaena strains are misidentified and highlight the need for taxonomic revision in this poorly studied cyanobacterial genus. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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9 pages, 1520 KiB

Open AccessArticle

Girdle Band Structure in the Diatom Genus Proschkinia (Bacillariophyta)—Another Potential Adaptation to Stabilise a Deep Cingulum?

by Eileen J. Cox

Diversity 2023, 15(6), 734; https://doi.org/10.3390/d15060734 - 02 Jun 2023

Viewed by 1029

Abstract

The girdle structure of Proschkinia (Bacillariophyta) is described in detail, showing the form of the unusual, channelled bands and how they link together. The significance and potential function of the more complex band structure is discussed in relation to its occurrence in other [...] Read more.

The girdle structure of Proschkinia (Bacillariophyta) is described in detail, showing the form of the unusual, channelled bands and how they link together. The significance and potential function of the more complex band structure is discussed in relation to its occurrence in other diatom genera and to other potential stabilising elements. Although some similarities in girdle structure are seen with the diatom genus Undatella, there is currently no evidence of a close phylogenetic relationship between these genera. Based on the current molecular data, Proschkinia is most closely related to the genus Fistulifera, with which it shares a distinctive valve feature, a fistula. Because of the traditional focus on valve morphology, far less is known of the girdle structure within the diatoms, despite its importance for maintaining cell integrity and allowing cell growth. The importance of studying the girdle structure as well as the valve morphology in diatoms in relation to their phylogeny and ecology is stressed. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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31 pages, 35715 KiB

Open AccessArticle

Appraisal of the Genus Pleurastrum (Chlorophyta) Based on Molecular and Climate Data

by Katia Sciuto, Marion A. Wolf, Michele Mistri and Isabella Moro

Diversity 2023, 15(5), 650; https://doi.org/10.3390/d15050650 - 10 May 2023

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Abstract

Two green microalgal strains, CCCryo 469-16 and CCCryo 470-16, were isolated from samples of Antarctic microflora. Their morphology and 18S rRNA sequences indicated a phylogenetic relationship with strains of the genera Chlorococcum Meneghini, Macrochloris Korshikov, and Pleurastrum Chodat. The last genus is considered [...] Read more.

Two green microalgal strains, CCCryo 469-16 and CCCryo 470-16, were isolated from samples of Antarctic microflora. Their morphology and 18S rRNA sequences indicated a phylogenetic relationship with strains of the genera Chlorococcum Meneghini, Macrochloris Korshikov, and Pleurastrum Chodat. The last genus is considered particularly problematic as it underwent several revisions. Moreover, its type strain, P. insigne SAG 30.93, was recently demonstrated to coincide genetically with the authentic strain of Chlorococcum oleofaciens from an 18S rRNA phylogeny. This deprived the genus Pleurastrum of an important type reference. Thus, the molecular markers rbcL, tufA, and ITS were employed to identify the Antarctic isolates more precisely. Several other microalgae related to our isolates were obtained from international culture collections for comparison. The obtained results allowed the re-establishment of strain P. insigne SAG 30.93 as the reference strain and the definition of the molecular borders of both genera Pleurastrum and Chlorococcum. Based on our findings, several Chlorococcum species are now re-attributed to Pleurastrum, as well as Macrochloris rubrioleum, here re-named Pleurastrum rubrioleum comb. nov., to which the Antarctic isolates also belong. Finally, a relationship between Pleurastrum lineages and climate zones was established. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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18 pages, 3907 KiB

Open AccessArticle

Description of Cylindrospermum solincola sp. nov. from Jammu and Kashmir, India and Further Insights into the Ecological Distribution and Morphological Attributes of Cylindrospermum badium

by Naresh Kumar, Aniket Saraf, Sagarika Pal and Prashant Singh

Diversity 2023, 15(5), 592; https://doi.org/10.3390/d15050592 - 25 Apr 2023

Cited by 1 | Viewed by 1405

Abstract

Two cyanobacterial strains KUT1-PS and 18C-PS were collected from the soil surface and vernal pool, respectively, from the Basantgarh village, Udhampur district of the union territory of Jammu and Kashmir, India and characterized by a polyphasic approach. The morphological characterization indicated that both [...] Read more.

Two cyanobacterial strains KUT1-PS and 18C-PS were collected from the soil surface and vernal pool, respectively, from the Basantgarh village, Udhampur district of the union territory of Jammu and Kashmir, India and characterized by a polyphasic approach. The morphological characterization indicated that both the strains showed typical Cylindrospermum-like morphology and probably belonged to the genus Cylindrospermum. Further, phylogenetic interpretations at the genus level were made using the 16S rRNA gene while the 16S-23S ITS region phylogenetic analysis and secondary structure analysis were conducted to enhance the resolution at the species level. The results from the comparative morphological analysis, the 16S rRNA gene percent similarity and phylogenetic analyses, the 16S-23S ITS percent dissimilarity and the ITS secondary structure analyses provided enough evidence that the strain 18C-PS is a representative of Cylindrospermum badium, providing further insights into its ecological distribution and morphological attributes. Additionally, the strain KUT1-PS was a novel species of the genus Cylindrospermum and is referred to herein as Cylindrospermum solincola sp. nov., in accordance with the International Code of Nomenclature for algae, fungi and plants. This study also discusses the importance of comparing the newly sequenced strains with previously established species before making final taxonomic interpretations. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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22 pages, 8230 KiB

Open AccessArticle

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

by Elena S. Krivina, Lidia A. Bobrovnikova, Anna D. Temraleeva, Alexandra G. Markelova, David A. Gabrielyan and Maria A. Sinetova

Diversity 2023, 15(4), 513; https://doi.org/10.3390/d15040513 - 03 Apr 2023

Cited by 2 | Viewed by 1768

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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Review

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22 pages, 1154 KiB

Open AccessReview

Emerging Technologies for the Discovery of Novel Diversity in Cyanobacteria and Algae and the Elucidation of Their Valuable Metabolites

by Gabrielle Zammit, Maria G. Zammit and Kyle G. Buttigieg

Diversity 2023, 15(11), 1142; https://doi.org/10.3390/d15111142 - 14 Nov 2023

Viewed by 1410

Abstract

Until recently, the study of cyanobacteria and microalgae has been hampered by the need to cultivate these organisms to gain insight into their cytomorphology, life cycle and molecular biology. However, various microbial species characterized by thick sheaths of exopolymeric substances were difficult to [...] Read more.

Until recently, the study of cyanobacteria and microalgae has been hampered by the need to cultivate these organisms to gain insight into their cytomorphology, life cycle and molecular biology. However, various microbial species characterized by thick sheaths of exopolymeric substances were difficult to isolate in culture due to their associated symbiotic bacteria. Other microbes evaded culture. Such challenges have now been overcome by the development of metagenomic techniques that allow direct DNA sequencing from environmental samples, as well as high resolution microscopy techniques that permit direct imaging of environmental samples. The sampling of understudied taxa from extreme environments and of toxic species has been facilitated by specialized robotic equipment. Single-cell sequencing has allowed for the proper characterization of microalgal species and their response to environmental changes. Various strains of cyanobacteria, microalgae and macroalgae have gained renewed interest for their high-value metabolites. This paper provides an overview of the emerging technologies and explains how they are being used to identify such strains and their products for industrial application. Advances in genetic engineering and CRISPR technology have facilitated the production of strains that are more amenable to culture, metabolite extraction, scale-up and application in biorefinery approaches. Emerging analytical techniques are discussed, with the advent of multiomics and its application in this field. Full article

(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)

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