POLYPHASIC STUDY OF ANTARCTIC CYANOBACTERIAL STRAINS¹

Abstract

We isolated 59 strains of cyanobacteria from the benthic microbial mats of 23 Antarctic lakes, from five locations in two regions, in order to characterize their morphological and genotypic diversity. On the basis of their morphology, the cyanobacteria were assigned to 12 species that included four Antarctic endemic taxa. Sequences of the ribosomal RNA gene were determined for 56 strains. In general, the strains closely related at the 16S rRNA gene level belonged to the same morphospecies. Nevertheless, divergences were observed concerning the diversity in terms of species richness, novelty, and geographical distribution. For the 56 strains, 21 operational taxonomic units (OTUs, defined as groups of partial 16S rRNA gene sequences with more than 97.5% similarity) were found, including nine novel and three exclusively Antarctic OTUs.Sequences of Petalonema cf. involvens and Chondrocystis sp. were determined for the first time. The internally transcribed spacer (ITS) between the 16S and the 23S rRNA genes was sequenced for 33 strains, and similar groupings were observed with the 16S rRNA gene and the ITS, even when the strains were derived from different lakes and regions. In addition, 48 strains were screened for antimicrobial and cytotoxic activities, and 17 strains were bioactive against the gram-positive Staphylococcus aureus, or the fungi Aspergillus fumigatus and Cryptococcus neoformans. The bioactivities were not in coincidence with the phylogenetic relationships, but rather were specific to certain strains.

Global distribution of cyanobacterial ecotypes in the cold biosphere

“…Many bacteria and microbial eukaryotes have been identified as possibly endemic to Antarctica, including several cyanobacterial species (Komárek, 1999;Taton et al, 2006b). However, our clone-library analyses indicate that three taxa previously identified as Antarctic endemics (Phormidum priestleyi Fritsch, L. frigida (Fritsch) Anagn.…”

“…and Kom. ; Komárek, 1999;Taton et al, 2006b) were more than 99% similar to sequences from the Canadian High Arctic (Table 2); for example, ArC05 is 99.6% similar to P. priestleyi (ANT.PROGRESS2.6; AY493585) and ArC13 is 99.8% similar to L. antarctica (ANT.LH18.1; AY493607). Furthermore, several of the uncultured cyanobacterial clones from East Antarctica and the McMurdo Dry Valleys identified as endemic, had the highest percentage match, up to 99.9%, to some of our High Arctic sequences.…”

Analysis of Antarctic proteobacteria by PCR fingerprinting and screening for antimicrobial secondary metabolites

“…Poorly explored areas or unusual environments have become critical for the discovery of novel compounds and bacteria (Saadoun and Gharaibeh, 2003;Lam, 2007;Newman and Cragg, 2007;Thakur et al, 2007). Therefore, soil samples taken from the Antarctic, one of the coldest and most poorly explored regions of the world, present good potential for the discovery of novel bioactive metabolites and compounds from microorganisms like bacteria (Marinelli et al, 2004;Tindall, 2004;Taton et al, 2006). This study was conducted to investigate the diversity and antimicrobial bioactivity of proteobacteria by performing isolation, molecular identification, molecular characterization, and bioactive secondary metabolite screening using 4 high-throughput screening models.…”

“…Poorly explored areas like the Antarctic present significant potential for the discovery of novel microorganisms like bacteria and biological active metabolites (Moncheva et al, 2002;Marinelli et al, 2004;Tindall, 2004;Taton et al, 2006;Bull and Stach, 2007). Barrientos Island is located at 62°24'S, 59°47'W, at the north entrance to the English Strait between Greenwich and Robert Islands.…”

Bacterial Diversity in the Hyperalkaline Allas Springs (Cyprus), a Natural Analogue for Cementitious Radioactive Waste Repository

“…Interestingly, these Cyanobacterial sequences were closely related to Leptolyngbya isolates from Antarctica (Taton et al 2006), and a separate study has shown that Leptolyngbya species dominate the microbial communities on stromatolite benthic samples from the alkaline (pH 10.4) lake Untersee in Antarctica (Andersen et al 2011). In addition, Cyanobacterial stromatolite-related sequences were also detected in the microbial mat sample (40% of the clones) from the Del Puerto Ophiolite, and have been linked to biological precipitation of carbonates (Blank et al 2009).…”