PDA

View Full Version : Detailed study of ultra-small bacteria



Swift
2015-Mar-02, 03:35 PM
These very tiny bacteria (tiny for bacteria) are often looked at as examples of what we might find on other worlds. IIRC, they were the model of what was thought to be fossil evidence in the Martian meteorite.

Now, some detailed work has been done to study them. R&D magazine (http://www.rdmag.com/news/2015/03/first-detailed-microscopy-evidence-bacteria-lower-size-limit-life?et_cid=4440917&et_rid=54636800&location=top)


Scientists have captured the first detailed microscopy images of ultra-small bacteria that are believed to be about as small as life can get. The research was led by scientists from the U.S. Dept. of Energy (DOE)ís Lawrence Berkeley National Laboratory (Berkeley Lab) and the Univ. of California, Berkeley. The existence of ultra-small bacteria has been debated for two decades, but there hasnít been a comprehensive electron microscopy and DNA-based description of the microbes until now.

The cells have an average volume of 0.009 cubic microns. About 150 of these bacteria could fit inside an Escherichia coli cell and more than 150,000 cells could fit onto the tip of a human hair.

The scientists report their findings in Nature Communications.

Colin Robinson
2015-Mar-07, 08:23 AM
These very tiny bacteria (tiny for bacteria) are often looked at as examples of what we might find on other worlds. IIRC, they were the model of what was thought to be fossil evidence in the Martian meteorite.

Now, some detailed work has been done to study them. R&D magazine (http://www.rdmag.com/news/2015/03/first-detailed-microscopy-evidence-bacteria-lower-size-limit-life?et_cid=4440917&et_rid=54636800&location=top)

Very interesting. These seem to be slightly bigger than the bacteria-shaped objects (BSOs) in meteorite ALH84001, but not by much.

Comparing diameters, the BSOs in the meteorite range from 0.02 microns up to 0.1 microns in diameter. The bacteria cells in the latest study were filtered through 0.2 micron filters, imply diameters under 0.2 microns.

Comparing volumes, the BSOs in the meteorite apparently have maximum lengths around 0.4 microns, and are roughly cylindrical, so the maximum volume is around 0.003 cubic microns. The cells in the latest study have average volume 0.009 cubic microns.

NASA's Allan H. Treiman said in 2003 (http://planetaryprotection.nasa.gov/summary/alh84001) that the BSOs in the meteorite were unlikely to be whole fossilised microbes because they are around "1/10 the volume of the smallest known free-living terrestrial bacteria". That statement may have been true in 2003, but it looks like it is no longer true today...