Under the most hostile features of the surface of our planet is a biological frontier as big and mysterious as deep space. Even in extreme heat of hydrothermal vents to pitch black lakes underneath glaciers, an awe-inspiring amount of life is hidden to our vision-and our research labs. Scientists have given this unmapped biosphere, the label microbial dark matter, borrowing that term of astrophysicists because, like its astronomic namesake, we have learnt that it is there but cannot decide what it is. But perhaps buried in all these forgotten genetic records is the solution to new developments in health care, weather projections and even life itself.
It is baffling to imagine that only an approximate percentage of 70 to 90per cent of microbial species have never been cultured or fully sequenced. It is not some outlying statistic, and it is the conclusion of dozens of microbiology studies published since 2018. A great deal of this concealed variety is just being discovered, due to advances in metagenomic sequencing. A huge branch of bacteria previously unknown altogether, the Candidate Phyla Radiation was first sighted in Californian groundwater just a few years back. The genomes of many of these microbes are too small and well-adapted in such hard conditions that they are unable to live in any other environments. And, by the way, if you ever considered microbes as nothing but pond slime or bacteria in the guts, then you have missed a much richer tale.
What Makes These Hidden Microbes So Special?
We tend to conceive of microbial dark matter as one more scientific oddity, yet the implications are very real indeed. Scientists are beginning to realize that microbes that are not cultivated are of crucial aspects that we depend on them, such as carbon cycling, and nutrient transformation. This can mean that when a group of the Max Planck Institute drilled into permafrost in Siberia, they found new archaea producing methane and at surprising levels. That warming, in its turn, leads to the release of additional quantity of permafrost due to methane. It is like a climate feedback loop staring us right in the face.
These less than well-known organisms present some of the most exciting leads on antibiotic discovery. Recently, scientists at the NovoBiotic Pharmaceuticals discovered a bacterium present in the soil, whose genetic pathways could potentially create an antibiotic, teixobactin which demonstrates efficacy over drug resistant pathogen. We would not have known that there were such molecules, though, without sequencing uncultivated DNA.
And then there is that query that pulls sleepless nights to NASA scientists, that is: why would things be different in and on Europa or Enceladus, should life evolve there to survive in the boiling vents or under ice as it did here in the Earth?
How Scientists Are Peering Into the Genetic Shadows
Most of these microbes cannot be cultivated in the traditional lab techniques resulting in the high utility of metagenomics. To simplify, scientists; pull all the DNA out of an environment; say, a handful of deep sea mud or a piece of Antarctic ice, and then use it like a humongous jigsaw puzzle.
Look at an example of a 2023 study in Nature Microbiology the authors of which sequenced the samples collected in the Atacama Desert, one of the driest places globally, located in Chile. They pieced together hundreds of incomplete genomes, including those of enzymes that might be used to create drought resistant crops. and last year researchers in Greenland unveiled microbial dark matter populations beneath melting glaciers found that ancient carbon reserves were being broken down by unique methanogens.
Such innovations are based on the next-generation tools:
- MetaSPAdes is high-performance genome assembler that has been found to perform with complex microbial communities.
- CheckM that approximates genome completion and contamination
- Not all sequences predictable and metabolic pathways with machine-learning This was predicted by metabolic pathway models trained with partial sequence
According to Dr. Jill Banfield of UC Berkeley in the interview on 2024:
It is only now that we are realizing what has been there. Each brand-new sequence is an eye-opener.”
From Alien Worlds to Everyday Solutions
The interdisciplinarity of this study is one of the most intriguing ones about it. Microorganisms living in association with volcanic rock on the ocean depth on the Mariana Trench may provide a template to search extraterrestrial biosignatures in the future. The cooperation of NASA with Ocean Exploration Trust already started providing information about the vent microbes to Mars life detection procedures.
However, it is not only the issue of space. Take the example of the simple PCR test a diagnostic device that everyone knows about following COVID-19. It is an enzyme found in Thermus aquaticus, an extremophile, best-known by virtue of being found in the Yellowstone hot springs, that makes PCR work. When one microbe changed molecular biology, how much will thousands of unknown microbes do.
As an example, biotech companies are combing deep-sea samples to see which polymerases can work under high pressure or acidic conditions. These enzymes may transform genetic engineering or environmental clean up.
Conclusion: A Frontier We Can No Longer Ignore
Microbial dark matter seems like one more rabbit hole of science, but the implications are too large to pass them off. Our climate models and our drug finding systems and our ideas about life limits are all based on uncultured microbes. By not engaging in the decoding process of this silent majority, we will risk losing answers to some of the most pressing questions of mankind.
So, an idea comes to mind, that is, 90 percent of the life forms on Earth remain unknown to us, so are we in reality familiar with this planet? Or ourselves? The next time you read some news about the finds in distant galaxies, keep in mind new alien worlds might exist right under your feet.