Phylogenetic relationships and taxonomic position of Chlorella-like isolates from low pH environments (pH < 3.0)

Little is known about phytoplankton communities inhabiting low pH environments such as volcanic and geothermal sites or acidic waters. Only specialised organisms are able to tolerate such extreme conditions. There is, thus, low species diversity. We have characterised the previously isolated acid to...

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Bibliographic Details
Published in:BMC evolutionary biology 2002-08, Vol.2 (1), p.13-13, Article 13
Main Authors: Huss, Volker A R, Ciniglia, Claudia, Cennamo, Paola, Cozzolino, Salvatore, Pinto, Gabriele, Pollio, Antonino
Format: Article
Language:English
Subjects:
Adaptation, Physiological
Chlorella
Chlorella - classification
Chlorella - genetics
Chlorella - ultrastructure
Chlorella protothecoides
Chlorella saccharophila
DNA, Ribosomal Spacer - genetics
Ecology
Evolution, Molecular
Hydrogen-Ion Concentration
Koliella
Molecular Sequence Data
Nannochloris
Phylogeny
RNA, Ribosomal, 18S - genetics
Viridiella fridericiana
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Summary:Little is known about phytoplankton communities inhabiting low pH environments such as volcanic and geothermal sites or acidic waters. Only specialised organisms are able to tolerate such extreme conditions. There is, thus, low species diversity. We have characterised the previously isolated acid tolerant Chlorella-like microalgae Viridiella fridericiana and Chlorella protothecoides var. acidicola by microscopical and biomolecular methods in order to assess their phylogenetic relationships. Both isolates belong to the trebouxiophycean lineage of chlorophytes. 18S and ITS1 sequence data clearly confirm that Viridiella fridericiana constitutes a new genus apart from the morphologically similar and likewise acid tolerant microalga Chlorella saccharophila. Chlorella protothecoides var. acidicola on the other hand is not a variety of Chlorella protothecoides but falls within a heterogeneous cluster consisting of Nannochloris, "Chlorella" spec. Yanaqocha, and Koliella, and is most closely related to algae which were also isolated from extreme environments. The distribution of acid tolerant strains in the 18S rRNA tree shows that acquisition of acid tolerance was unlikely a monophyletic event in green microalgae. We propose that different strains have independently adapted to extreme environments. Some of them have spread worldwide and were able to colonise other extreme habitats. Considering the problems of successfully isolating acid tolerant strains, acidic soils could represent an unsuspected source of biological diversity with high potential for biotechnological utilisations.
ISSN:1471-2148
1471-2148
DOI:10.1186/1471-2148-2-13