Thirty viable non-axenic cyanobacterial strains were isolated from 28 Siberian permafrost cores. Filamentous heterocystous (Nostocales) and non-heterocystous (Oscillatoriales) cyanobacteria were recovered (Vishnivetskaya et al. 2001). The 16S rRNA genes from representative strains of each order were sequenced. Seven out of eight strains of the order Oscillatoriales were close to each other and to Leptolyngbya with identity 80-95.8%, and one strain was closely related to Microcoleus with identity 96.8% (Fig. 6.1). The phylogenetic analyses were confirmed by studying the morphological features of the isolates. Cyanobacteria of the Oscillatoria-Leptolyngbya group, with narrow straight uniseriate trichomes, were often isolated from both young and old permafrost sediments. The Microcoleus-like strain 195A20 grew at both 27°C and 4°C, with a doubling time of 20 h at 24°C. The strain 195A20 showed morphological plasticity with respect to growth temperature, trichomes usually being shorter and wider at 27°C than at low temperature (Vishnivetskaya et al. 2003). According to the 16S rRNA analysis, three cyanobacterial strains had close relatives within the order Nostocales (Fig. 6.1). Viable strains of the Nostoc and Anabaena formed heterocysts in the absence of a combined nitrogen source, and were characterized by different phycoerythrin/phycocy-anin ratios depending on nitrogen source and light wavelength (Erokhina et al. 1999, 2000; Vishnivetskaya et al. 2001). Viable cyanobacteria were dominated by

str. 790-AC2, Siberian permafrost 1.6 m Nostocpunctiforme SAG 68.79, lichen symbiont (DQ185256) Nostoc ATCC 53789 (AF062638) Nostoc sp. 8963, symbiont (AY742449) Nostoc commune, soil (AB113666) str. 195-A22, Siberian permafrost 14.8 m str. 195-A21, Siberian permafrost 14.9 m Nostocsp. PCC 9229, symbiont (AY742451)

j-Uncultured cyanobacterium FreP27, microbial mat Fresh Pond Antarctica (AY541582)

-Anabaena augstumaiis SCMIDKE JAHNKE/4a (AJ630458)

Uncultured cyanobacterium TAF-B14, epilithon River Taff UK (AY038728) I environmental clone ES35D6, Antarctic permafrost 1.7 m

-1— environmental clone ES35D7, Antarctic permafrost 1.7 m

^^621-environmental clone ES35B10, Antarctic permafrost 1.7 m

'— environmental clone ES35E3, Antarctic permafrost 1.7 m — Uncultured cyanobacteria, microbiä mat Lake Fryxel Antarctica (AY151721) str. 195-A20, Siberian permafrost 14.2 m

Microcoleus vaginatus PCC9802, soil Colorado Plateau (AF284803) Oscillatoria prolifera PCC 7907 (AB075993) Osciiiatoria sp. PCC7112 (AB074509) 1001— str. 193-AC128, Siberian permafrost 4.0 m Leptoiyngbya sp. CNP1-B1-4 (AY239603)

Oscillatoria sp. CCAP 1459/26 (AY768396)

841-LPP-group cyanobacterium QSSC8cya, sublithic communities Antarctica (AF170758)

-Uncultured cyanobacterium BGC-Fr054, microbial mat Lake Fryxel Antarctica (AY151722)

Uncultured cyanobacterium FBP256, cryptoendolithic community Antarctica (AY250870) Osciiiatoria negiecta M-82 (AB003168)

Uncultured cyanobacteria SalP09, microbial mat Salt Pond Antarctica (AY541528) Oscillatoria sp. Ant-SOS, Antarctica (AF263342) str. 195-A7, Siberian permafrost 10.3 m Leptoiyngbya sp. 0BB19S12 (AJ639895) str. 594-AC3, Siberian permafrost2.05 m Leptoiyngbya sp.PCC 7104 (AB039012) str. 195-A12, Siberian permafrost 2.4 m str. 193-AC5, Siberian permafrost 4.0 m str. 690-CA125, Siberian permafrost 5.7m str. 294-AC4, Siberian permafrost 50.3 m

Oscillatoriales o p

Fig. 6.1 Phylogenetic relationship of cyanobacterial isolates and environmental clones derived from Siberian and Antarctic permafrost (the phylogenetic tree was adopted from Gilichinsky et al. 2007a). Tree was produced by the neighbor-joining method (Saitou and Nei 1987). Bootstrap values, expressed as percentages of 100 replications, higher than 40% are shown. Sequences were deposited in GenBank non-heterocystous filamentous cyanobacteria of the order Oscillatoriales. While no viable cyanobacteria were detected in any of 56 Antarctic permafrost samples, a few 16S rRNA cyanobacterial environmental clones were obtained from the total community genomic DNA extracted from Antarctic permafrost of depth 1.7 m (Gilichinsky et al. 2007b). The phylogenetic analyses of the environmental clones and isolates obtained from the permafrost samples of both Polar Regions did not show any matches. Nine environmental clones were affiliated with the genus Anabaena, and they were closely related to an uncultured cyanobacterium found in river epilithon (O'Sullivan et al. 2002). We have found that viable permafrost cyanobacteria were closely related to strains and more often to uncultured cyano-bacterial clones derived from a microbial mat or cryptoendolithic communities in Antarctica (Gilichinsky et al. 2007b).

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