Extremophiles Expose the Secrets of Extraterrestrial Life
While humans might not call deep-sea trenches or mountaintops home, some remarkable microorganisms do! Known as extremophiles, these tiny organisms have adapted to survive in incredibly harsh environments. Studying their survival strategies in these hostile conditions could be valuable clues for scientists searching for life on Earth and beyond.
A recent study highlights a method for accurately identifying extremophiles based on protein fragments instead of genetic material. The study also identified two new hardy bacteria from the hostile high-altitude lakes in Chile, an environment resembling early Mars.
Identification of Earth-bound microorganisms has traditionally relied on a method called gene sequencing. This technique analyzes the unique sequence of nucleotides that make up an organism’s DNA. By comparing the sequences to existing databases, scientists can identify known species or discover entirely new ones.
However, the wonders of gene sequencing cease to exist when encountered with extremophiles, particularly the closely related strains. Their genetic similarities could make it challenging to distinguish them using this method. This hurdle prompted Dr. Ralf Moeller and his team to explore an alternative approach to protein fingerprinting.
Unlike DNA, which remains largely unchanged within an organism, proteins exhibit greater variation depending on their specific function. By analyzing the protein signature of extremophiles, scientists can potentially achieve a more precise identification, even when dealing with closely related species.
The researchers put their protein fingerprinting technique to the test in the harsh environment of the Chilean Altiplano. They collected water samples from five lakes perched more than 2.3 miles above sea level. From the samples, the researchers cultivated 66 microbes and then determined which method identified the microorganisms.
The gene sequencing method compared a specific gene (16s rRNA) from each microbe to a vast database for identification. The protein fingerprinting or “proteotyping” technique, on the other hand, analyzed protein fragments unique to each microbe, creating a personalized “peptide signature” for comparison with proteome databases.
While both methods showed impressive results, where 63 out of 66 cultivated microbes were identified, the gene sequencing fell short in identifying the other three since the genetic information wasn’t present in the database. This is where proteotyping was proved superior. By analyzing their protein signatures, the researchers were able to identify two of these unidentified microbes as potentially entirely new types of extremophile bacteria.
This groundbreaking discovery highlights the immense potential of protein fingerprinting. It offers a more comprehensive solution for identifying extremophiles, especially from limited samples or those with yet-uncatalogued DNA. As Dr. Moeller and his team envision, this technique could be instrumental in the future of astrobiology, aiding the search for life beyond Earth. Moreover, it promises to revolutionize our understanding of microbial diversity right here on our planet.
REFERENCES
- Runzheimer K, Lozano C, Boy D, Boy J, Godoy R, Matus FJ, Engel D, Pavletic B, Leuko S, Armengaud J, Moeller R. Exploring Andean High-Altitude Lake Extremophiles through Advanced Proteotyping. J Proteome Res. 2024;23(3):891. DOI: 10.1021/acs.jproteome.3c00538.
- American Chemical Society. Protein fragments ID two new 'extremophile' microbes--and may help find alien life. ScienceDaily. 2024 Mar 15. [cited 2024 Mar 24]. Available from: <www.sciencedaily.com/releases/2024/03/240315160906.htm>.
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