A vast majority of all species on Earth are microbes, but only a tiny fraction of them are recognized by science because less than 10 percent of them can be grown in the lab for study. The other 90-plus percent can only survive under the natural conditions of their native environment, and those environments are often obscure niches. (Think: within the gut of a particular species of weasel, or within the acidic depths of a hydrothermal pool.)
These organisms represent monumental gaps in our knowledge of the natural world. They are what some researchers have called "the microbial dark matter." We know they're out there, but we don't know anything about their nature.
That could soon change, however, thanks to a breakthrough technique called metagenomics, reports New Scientist. Essentially, metagenomics involves taking an environmental sample and combing it for all of the DNA that can be found within it. It's messy, but with the correct tools to analyze these samples, scientists can begin to piece together the genomes of all the organisms within them.
“It’s like getting a mix-up of lots of different jigsaw puzzles, and then trying to put together the pieces of each individual puzzle,” explained Donovan Parks at the University of Queensland in Australia.
'Crazy new levels of stuff'
The methodology is already off to an alarmingly successful start. For instance, Parks and colleagues recently used it to analyze more than 1,500 metagenomes that researchers worldwide had uploaded to a public database. From those samples, nearly 8,000 microbial genomes were reconstructed — a whopping third of which were new to science.
Even more startling, these newly discovered microbes were so different from anything ever identified before that researchers had to add 20 new phyla to the tree of life, just to categorize them. Phyla are some of the heaviest branches on the tree of life; they're the next rung below biological kingdoms. To put things in perspective, consider that these new microbes were as distantly related to other known microbes as humans are to insects.
"This is crazy new levels of stuff,” said Nicholas Coleman at the University of Sydney.
The real value of this knowledge is difficult to quantify at this early stage, but it's likely paramount. These new microbes could yield powerful new antibiotics, for instance. Perhaps there are microbes that break down plastic pollution, or assist in the development of new natural industrial chemicals. The possibilities are endless, especially considering just how little we already know about the microworlds all around us.
“There’s still a whole lot that we don’t know,” added Coleman. “There are so many crazy environments out there, and even two patches of dirt side-by-side can have different organisms.”
The research was published in the journal Nature Microbiology.