Project #3925, Revival of non-culturable microorganisms from Siberian permafrost soil, came to completion in the last quarter. The aim was to analyse the microbial community in Russian permafrost samples. The 34 soil samples investigated were collected from the northeastern Arctic tundra in Russia, which is characterized by continuous permafrost. The three sampled groups had a geological age of 1.8-2 million years, 20,000-35,000 years and 6,000-8,000 years. 

There is a number of studies on Siberian permafrost, however, the viability of microorganisms in these samples still remained disputable. But the team of scientists from the G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms (Russia) proved the presence of viable microorganisms.

The research involved the optimization of a number of techniques, such as the treatment of permafrost samples and the visualization of microorganisms by high resolution in situ electron microscopy and fluorescence microscopy. It was demonstrated that the samples contained a large amount (up to 80%) of cells with undamaged structure. This was the prerequisite for the next steps. 

The development of novel reactivation-based microbiological techniques allowed the isolation of 280 pure bacterial strains, 109 of which were subjected to a molecular analysis in order to determine the taxonomic position of these strains. 17 strains are currently being described as representatives of novel species or genera. 

Another task was related to the detection of nanocells (ultramicrobacteria), which are very small (250-300 nm) and extremely difficult to work with. Accordingly, there is very little information on these cells in frozen environments. Surprisingly, the microbial community in some permafrost samples contained more than 60% of such nanocells. The construction of a bacterial clone library showed the presence of 13 phylotypes, most of them belonging to the phyla Actinobacteria and Proteobacteria. 

The results of this study will have a major impact on international research on permafrost.

Assessment by Rosa Margesin
Institute of Microbiology, University of Innsbruck, Austria. 
Field of expertise: psychrophilic microorganisms in alpine habitats, environmental microbiology (low-temperature biodegradation and bioremediation in cold areas), soil microbiology