Hundreds of thousands of years ago, the earth coexisted with various already extinct animals, flora, microorganisms, bacteria and viruses in an environment that is probably very different from the one we inhabit today, and of which we know little. Our planet is an infinite blanket of questions, but it is this same one, which houses clues to be able to decipher them and thus be able to understand and understand ourselves.
In 1980 micro-organisms were investigated in the deep core of Vostok ice, which motivated other subsequent investigations related to this little-penetrating topic. In 1992 scientists took a sample of the ice core from the Guliya (Northwest Tibetan Plateau, China) ice sheet, which was kept at -5 ° in a laboratory. Then in 2015 a second sample of ice core was taken from that place and it was preserved in the same way for further investigation. Recently, scientists at Ohio State University analyzed both nuclei to identify the microbial communities contained in the ice, and discovered 33 groups of viruses, some very old with an estimated date of 15,000 years, 28 of these groups are completely unknown until now.
These reports indicated that microbial biomass is very low in most glacial ice samples, with an estimated number of microbial cells ranging from 10 2 to 10 4 cells ml −1 , compared to the concentration of eg 10 4 –10 6 cells ml −1in sea water. The microbes contained in the ice core of glaciers serve as an interpretation to represent microbes in the atmosphere at the time of deposition, in addition to their climatic and environmental conditions during that time period. Dominant bacteria have optimal growth temperatures well above freezing, allowing them to successfully grow in cold environments such as glacial ice. Scientists do not yet show activity in situ, but some studies postulate a possible microbial activity, since some gases in excess (CO2, CH4 and N2O) have been detected, which can be produced by postpositional microbial metabolisms.
Frozen air bubbles on glacial surface. Source: Marcos Cole
Viruses are the most numerous components of microbial communities in the oceans and can alter the activities of these communities through lysis. Some of these abundant viruses in sea ice could infect dominant microbial members in the community, modulating host adaptations to extreme cold and salt conditions. If we consider these as indicators, then the viruses stored in the glacial ice may also have infected concurrent microbial hosts, before or after the formation of the ice.
Results and Decisions
To develop a clean surface decontamination procedure and eliminate possible microbial contaminants acquired during the extraction, handling and transportation of both nuclei (the sample taken in 1992 and the second one taken in 2015), and thus guarantee pristine and clean samples for research Microbially, the experts constructed sterile artificial ice core sections and covered them with a known bacterium (strain 18 Cellulophaga baltica, CBA 18), virus (phage Pseudoalteromonas PSA-HP1) and free DNA. When starting the decontamination protocol, they cut (scraped) part of the outer layer of each central sample, then each of the samples was washed with ethanol and sterile water, to remove external layers of ice, a total of 1.5 cm of radius of the ice core.
Diagram of the decontamination process of glacial cores
Samples Differ
After decontamination, the composition of the microbial community between and within the ice cores was compared. The 32 most abundant genera, defined as those comprising at least 0.5% of sequences in at least one ice sample, collectively represented> 96.0% of each community. This indicates that the members that belong to these lineages are adapted to cold environments and can subsist for long periods of time, although their relative abundances vary according to the depths (ages) of the ice core. The S3 ice core samples shared some abundant genera with the PS ice core samples. Thus, There are fundamental differences in microbial communities between the ice cores recovered from the plateau (shallow end) and the top of the Guliya ice sheet. The differences of the microbial communities in both nuclei, lies in the elevations at which both nuclei were drilled, the core of the plateau at 6200 m and the core of the summit at 6650 m, which represents very different environmental conditions in terms of UV radiation, air temperature and oxygen concentration. All of these factors influence microbial communities at the time of deposition. Furthermore, all samples of the PS ice core came from the shallowest part of the ice sheet and were much younger (70 – 300 years), while the samples from the S3 core were longer (520 – 15,000 years). The differences of the microbial communities in both nuclei, lies in the elevations at which both nuclei were drilled, the core of the plateau at 6200 m and the core of the summit at 6650 m, which represents very different environmental conditions in terms of UV radiation, air temperature and oxygen concentration. All of these factors influence microbial communities at the time of deposition. Furthermore, all samples of the PS ice core came from the shallowest part of the ice sheet and were much younger (70 – 300 years), while the samples from the S3 core were longer (520 – 15,000 years). The differences of the microbial communities in both nuclei, lies in the elevations at which both nuclei were drilled, the core of the plateau at 6200 m and the core of the summit at 6650 m, which represents very different environmental conditions in terms of UV radiation, air temperature and oxygen concentration. All of these factors influence microbial communities at the time of deposition. Furthermore, all samples of the PS ice core came from the shallowest part of the ice sheet and were much younger (70 – 300 years), while the samples from the S3 core were longer (520 – 15,000 years). It represents very different environmental conditions in terms of UV radiation, air temperature, and oxygen concentration. All of these factors influence microbial communities at the time of deposition. Furthermore, all samples of the PS ice core came from the shallowest part of the ice sheet and were much younger (70 – 300 years), while the samples from the S3 core were longer (520 – 15,000 years). It represents very different environmental conditions in terms of UV radiation, air temperature, and oxygen concentration. All of these factors influence microbial communities at the time of deposition. Furthermore, all samples of the PS ice core came from the shallowest part of the ice sheet and were much younger (70 – 300 years), while the samples from the S3 core were longer (520 – 15,000 years).
conclusion
Glacier ice harbors a still unexplored universe of microbial life. The climatic change, translated in the increase of temperature, accelerates the glacial melting. This retreat will bring with it the release of glacial microbes and viruses that have been preserved in the ice for thousands of years. This means the loss of elemental viral and microbial files in decoding information about the climate regimes of yesteryear. From a much more negative perspective, this melting of ice could release unknown pathogens into the environment and affect the population.
