Chuck Bednar for redOrbit.com – @BednarChuck
Scientists have captured an image of what is apparently the world’s smallest known life form: a type of bacteria so small you could fit 150 of them into a single E. coli cell and 150,000 of them on the tip of a human hair.
The image was captured by scientists from the US Department of Energy’s Lawrence Berkeley National Laboratory and the University of California, Berkeley, and according to Gizmodo, the ultra-small bacteria it depicts is believed to be fairly common, but hard to photograph.
Their size isn’t the only reason for this, the website explains. The bacteria itself are exceptionally fragile and can easily die. The samples used for the new image were collected from groundwater and then flash frozen to -272 degrees Celsius before they were transported to the lab.
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Once they arrived, the frozen samples underwent 2D and 3D cryogenic transmission electron microscopy to characterize the size and internal structure of their cells. The images also showed that the cells were dividing, indicating that they were healthy microbes.
Next, the scientists took the bacteria to the DOE’s Joint Genome Institute in Walnut Creek, California and sequenced the genomes of the microbes. In addition, metagenomic and other DNA-based analyses of the samples were conducted at UC Berkeley, and a diverse range of bacteria from WWE3, OP11, and OD1 phyla were discovered.
According to the researchers, that these microbes are the smallest that a cell can be while still accommodating enough material to sustain life. The bacterial cells contain dense spirals that are most likely DNA, a handful of ribosomes, hair-like appendages, and a stripped-down metabolism that probably requires them to rely on other bacteria for many of life’s necessities.
Nobody understands these little guys
Furthermore, the bacteria are part of three microbial phyla that are poorly understood. Finding out more about organisms from these phyla could lead to new insights on the role of microbes in the planet’s climate, our food and water supply, and other key processes, the authors said. Their findings were published last month in the journal Nature Communications.
“These newly described ultra-small bacteria are an example of a subset of the microbial life on earth that we know almost nothing about,” co-corresponding author Jill Banfield, a professor in the UC Berkeley departments of Earth and Planetary Science and Environmental Science, Policy and Management, as well as a member of the Berkeley Lab, explained in a statement.
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She added that the bacteria are “enigmatic,” and that while they have been “detected in many environments and they probably play important roles in microbial communities and ecosystems,” she and her colleagues “don’t yet fully understand what these ultra-small bacteria do.”
“There isn’t a consensus over how small a free-living organism can be, and what the space optimization strategies may be for a cell at the lower size limit for life,” noted co-corresponding author Birgit Luef, a former postdoctoral researcher in Banfield’s group who is now affiliated with the Norwegian University of Science and Technology. “Our research is a significant step in characterizing the size, shape, and internal structure of ultra-small cells.”
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As a result of their work, the researchers were able to create the most complete description of ultra-small bacteria to date. They also discovered that some of the bacteria had pili, or thread-like appendages that found function as “life support” connections to other microbes. The genomic data revealed that the bacteria lack many basic functions, meaning that they apparently rely upon on a community of microbes for critical resources.
However, Banfield noted that there is still much to learn about these microbes. “We don’t know the function of half the genes we found in the organisms from these three phyla,” she said.
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