Permafrost Microbiology

Abstract

Numerous and various ecological and morphological groups of viable micro-organisms survive under permafrost conditions. They are the only known living organisms preserved over a geologically significant time. Their preservation within permafrost is of interest from both biological and geocryological points of view and forms the basis for a number of investigations in different scientific fields. The latter are performed not only upon morphological but also upon functional characteristics of viable cells. This approach is relevant to questions concerning the protective properties of unfrozen water and may provide new ways of solving major problems of historical geocryology. Of special interest is the interaction of both biological and geological knowledge to better understand the spatial and temporal limits of the biosphere. RESUMEDe nombreux groupes varies de micro-organismes survivent a leur emprisonnement dans le pergelisol. 11s constituent les seuls organismes qui sont prkservks aprks un temps gkologique significatif. Leur prkservation au sein du pergklisol est intkressante a la fois au point de vue biologique et gkocryologique, et elle constitue l'objet de nombreuses recherches dans diffkrents domaines scientifiques, notamment en ce qui concerne la morphologie mais aussi en ce qui concerne les caractkristiques fonctionnelles des cellules rksistantes. Ces recherches peuvent apporter des donnkes propos des possibilitks protectives de l'eau non gelee et peuvent aussi fournir des solutions a des problitmes fondamentaux de geocryologie historique. Ces recherches concernent en outre l'interaction entre les connaissances biologiques et gkologiques et aideront ZI mieux comprendre les limites spatiales et temporelles de la biosphitre. KEY WORDS: permafrost; micro-organisms: biology COLD-ADAPTED MICRO-ORGANISMSorganisms in natural environments, which mostly are at low temperatures. Including seawater, of Temperature is one of the most important which two-thirds has a temperature of around parameters regulating the activities of micro-+ 2"C, and polar regions, more than 80% of the

Bacterial communities in ancient permafrost profiles of Svalbard, Arctic

“…Recently, metagenomic efforts have shed light on the permafrost microbiome in some parts of Arctic such as Alaska [25], Svalbard [26], Canadian Arctic [27,28], and Greenland [29]. A wide diversity of culturable bacteria representing over 30 genera including Acinetobacter, Aeromonas, Alcaligenes, Arthrobacter, Bacillus, Brevibacterium, Cytophaga, Clostridium, Cellulomonas, Deinococcus, Exiguobacterium, Flavobacterium, Glaciimonas, Kocuria, Micrococcus, Mycobacteria, Myxococcus, Nitrobacter, Nitrosomonas, Nitrosospira, Paenibacillus, Promicromonospora, Pseudomonas, Psychrobacter, Rhodococcus, Serratia, Sporosarcina, Subtercola, and Streptomyces have been isolated from Arctic permafrost [10,17,19,22,23,30]. Furthermore, Hansen et al [31] and Variovorax) employing culture-dependent and culture independent methods from the permafrost soil of Spitsbergen (78°12′N, 15°50′E).…”

Depth‐Resolved Physicochemical Characteristics of Active Layer and Permafrost Soils in an Arctic Polygonal Tundra Region

“…In addition to the soil physical characteristics discussed above, pore water geochemical analysis provides valuable information for understanding its potential impacts on soil biogeochemical processes during permafrost thaw. Previous studies on saline permafrost soils revealed a diverse microbial population that are active at subzero temperatures although the activity is low (Gilichinsky et al, 2005;Gilichinsky & Rivkina, 2011;Rivkina et al, 2007). This microbial activity occurs primarily in the unfrozen water films/inclusions in the otherwise frozen soil, and this slow yet continuous long-term microbial metabolism could result in sustained winter time carbon flux (Fahnestock et al, 1999), spring thaw burst (Raz-Yaseef et al, 2017), and significantly change the soil biogeochemical characteristics.…”

Earth's perennially frozen environments as a model of cryogenic planet ecosystems

“…There are a number of environments in the biosphere that could preserve viable microorganisms over geological time. Comparisons of the number of viable microorganisms preserved in galite and amber at temperatures above 0°С with those preserved in the cryosphere at temperatures below 0°С have shown that the cryosphere hosts a larger amount of extremely diverse viable microorganisms …”

“…Thus, the unfrozen water films are characterized as a major ecological niche for microorganisms . Because these water films are not thicker than several nanometers and are considerably smaller than the size of the microbial cells, cell growth, division (ie, reproduction) and movement within the films are unlikely . The amount of unfrozen water and the thickness of the water films are independent of ice content.…”

“…71,73,113,[116][117][118][119] At the same time, 95% of the bacteria isolated from permafrost, do not grow at all or grow very poorly at temperatures above 30°C. 62 The survival of biota in frozen and supercooled saline Cenozoic ecosystems, as well as in Permo-Triassic salt deposits 120 are examples of the unique adaptation abilities of bacteria. It is important to understand whether the salt resistance of these cells is linked to their tolerance to low temperatures.…”