Smallest life form on Earth recorded

3 Mar 2015

A 3-D reconstruction of the micro-cell. The scale bar is 100 nanometers. Image via Berkeley Lab

Microscopic images of ultra-small bacteria have been captured for the first time, ending the debate surrounding the existence of what is believed to be the smallest form of life possible.

Researchers in the US produced the findings of the cells which have an average volume of 0.009 cubic micron, which is frightfully small when considering that one micron is one millionth of a metre.

It was a clever process that the team from the US Department of Energy’s Lawrence Berkeley National Laboratory used to make the findings.

They filtered Colorado groundwater over and over until the cells were 0.2 microns, “which is the size used to sterilise water,” according top

The results were not sterile, though, enriched with tiny microbes which were frozen to -272 degrees celsius in a wonderfully-named ‘cryo plunger’.

A bit of 2D and 3D cryogenic transmission electron microscopy, genome sequencing and “metagenomic and other DNA-based analyses” resulted in what we see today.

Microscopy and tiny life

The cells captured were just 0.009 cubic micron’s in size, which equates to 1/150,000th the diamater of a human hair. The scale bar is 100 nanometers. Credit: Berkeley Lab

“These newly described ultra-small bacteria are an example of a subset of the microbial life on earth that we know almost nothing about,” says Jill Banfield, a co-corresponding author of the paper which has been listed in Nature Communications.

“They’re enigmatic. These bacteria are detected in many environments and they probably play important roles in microbial communities and ecosystems. But we don’t yet fully understand what these ultra-small bacteria do,” says Banfield.

“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. Our research is a significant step in characterizing the size, shape, and internal structure of ultra-small cells,” says Birgit Luef, the other author.

Gordon Hunt was a journalist with Silicon Republic