  Low cyanobacterial diversity in biotopes of the Transantarctic Mountains and Shackleton Range (80-82°S), Antarctica.; ; et al in FEMS Microbiology Ecology (2011), 77 The evolutionary history and geographical isolation of the Antarctic continent have produced a unique environment rich in endemic organisms. In many regions of Antarctica, cyanobacteria are the dominant ... [more ▼] The evolutionary history and geographical isolation of the Antarctic continent have produced a unique environment rich in endemic organisms. In many regions of Antarctica, cyanobacteria are the dominant phototrophs in both aquatic and terrestrial ecosystems. We have used microscopic and molecular approaches to examine the cyanobacterial diversity of biotopes at two inland continental Antarctic sites (80-82°S). These are amongst the most southerly locations where freshwater-related ecosystems are present. Results showed a low cyanobacterial diversity, with only 3-7 Operational Taxonomic Units (OTUs) per sample obtained by a combination of strain isolations, clone libraries and DGGE based on 16S rRNA genes. One OTU was potentially endemic to Antarctica and is present in several regions of the continent. Four OTUs were shared by the samples from Forlidas Pond and the surrounding terrestrial mats. Only one OTU, but no Internal Transcribed Spacer (ITS) sequences, was common to Forlidas Pond and Lundström Lake. The ITS sequences were shown to further discriminate different genotypes within the OTUs. ITS sequences from Antarctic locations appear more closely related to each other than to non-Antarctic sequences. Future research in inland continental Antarctica will shed more light on the geographical distribution and evolutionary isolation of cyanobacteria in these extreme habitats. [less ▲] Detailed reference viewed: 20 (4 ULg) Exploring the Holocene through fossil cyanobacterial sequences from Antarctic lake sediments.Fernandez Carazo, Rafael  ; ; et alPoster (2009, July 27) Detailed reference viewed: 8 (0 ULg)Cyanobacterial diversity in the Transantarctic Mountains (Antarctica).Fernandez Carazo, Rafael ; ; Poster (2008, August 31) Detailed reference viewed: 4 (0 ULg)Cyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivities; ; et al in Journal of Applied Microbiology (2008), 105(1), 105-115 Aims: To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities. Methods and results ... [more ▼] Aims: To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities. Methods and results: In all, 51 Antarctic cyanobacteria isolated from benthic mats were cultivated in the laboratory by optimizing temperature, irradiance and mixing. Productivity was generally very low (£60 mg l)1 d)1) with growth rates (l) in the range of 0Æ02–0Æ44 d)1. Growth rates were limited by photosensitivity, sensitivity to air bubbling, polysaccharide production or cell aggregation. Despite this, 126 extracts were prepared from 48 strains and screened for antimicrobial and cytotoxic activities. Seventeen cyanobacteria showed antimicrobial activity (against the Gram-positive Staphylococcus aureus, the filamentous fungus Aspergillus fumigatus or the yeast Cryptococcus neoformans), and 25 were cytotoxic. The bioactivities were not in accordance with the phylogenetic grouping, but rather strain-specific. One active strain was cultivated in a 10-l photobioreactor. Conclusions: Isolation and mass cultivation of Antarctic cyanobacteria and LCMS (liquid chromatography ⁄ mass spectrometry) fractionation of extracts from a subset of those strains (hits) that exhibited relatively potent antibacterial and ⁄ or antifungal activities, evidenced a chemical novelty worthy of further investigation. Significance and impact of the study: Development of isolation, cultivation and screening methods for Antarctic cyanobacteria has led to the discovery of strains endowed with interesting antimicrobial and antitumour activities. [less ▲] Detailed reference viewed: 36 (5 ULg)Cyanobacterial diversity and distribution in the very extreme environments of the Pensacola Mountains (82°S, Antarctica).Fernandez Carazo, Rafael ; ; Wilmotte, Annick Speech (2006) Detailed reference viewed: 4 (0 ULg) |
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