Microbial Communities In Permafrost: Environmental Controls and Impacts

 By: Andrea R. Ortiz 

The figure above is from Alekseev et. al., 2020. Soil microbial communities at phylum taxonomic level within collected soil samples. 

    In Antarctica only about 0.1% of the region is considered ice free due to extreme temperatures and environmental conditions.  One ice free portion is found in Eastern Antarctica known as the Larsemann Hills. The permafrost of the Larsemann Hills is home to various microbial communities which are adapted to live in such extreme conditions. In a recent investigation of  Alekseev et. al., 2020 , various microbial communities were identified in the region along with their relationship to soil and impacts on the surrounding environment. 

  Using 3 sampling points of 50 x 50 m, a collection of soil samples from these sites were collected at various depths at dimensions of 20 x 20 cm. Each sample was taken in a double sterile bag to a laboratory where the soil was sieved before undergoing chemical analysis for pH, carbon - nitrogen content, and particle size distribution. The microbes identified in these conditions were found in a neutral pH due to the lack of salt accumulation, 10.48 and 16.33 carbon - nitrogen ratio because of peat material found in topsoil, and a distribution in sub-surface horizon due to fine earth formation. The individual microbes after analysis then underwent 16S rRNA gene pyrosequencing resulting in 12 bacterial and archaeal phyla being identified. Some of the collected samples included microbes such as Proteobacteria, Actinobacteria, Acidobacteria, Cyanobacteria, Gemmatimonadetes, Verrucomicrobia and many more. 

   The results of the study indicate that diverse soil microbial communities not only exists in such harsh conditions but are imperative to sustaining their ecosystem which include cycling of nitrogen,  determining carbon availability, and soil composition at multiple levels. However, in the study it was also observed that microbes that survive in extreme cold are ultimately impacted by moisture content in their environment and nutrient availability. Thus, future studies such as this should continue in order to comprehend microbial communities and effectively sustain the Antarctic ecosystem.   

Reference: 

Alekseev, I., Zverev, A., & Abakumov, E. (2020). Microbial communities in permafrost soils of Larsemann Hills, eastern Antarctica: environmental controls and effect of human impact. Microorganisms, 8(8), 1202.