A team of investigators out of Berkeley is reporting in the December 22 issue of Science a find of some of the smallest bacterial species ever:
For 11 years, Jill Banfield at the University of California, Berkeley, has collected and studied the microbes that slime the floors of mines and convert iron to acid, a common source of stream pollution around the world.
Imagine her surprise, then, when research scientist Brett Baker discovered three new microbes living amidst the bacteria she thought she knew well. All three were so small – the size of large viruses – as to be virtually invisible under a microscope, and belonged to a totally new phylum of Archaea, microorganisms that have been around for billions of years.
What made Baker’s find possible was shotgun sequencing, a technique developed and made famous by Celera Corp., which used it to sequence the human genome in record time…
“We were essentially looking for new stuff, and we found it in all the samples studied, though at low abundance,” said Baker, who is with the campus’s Department of Earth and Planetary Science. “Shotgun sequencing is a better way to identify organisms than using other methods, like culturing or PCR (polymerase chain reaction), which can miss quite a lot of organisms…”
Banfield noted that the bacteria and newfound Archaea living in the highly acidic mine drainage are archetypes of the kind of life that could exist on other planets, such as in the iron- and sulfur-rich soil of Mars.
These therefore could be the smallest organisms ever found, though Baker needs to culture them before confirming this. Because they’re so small, however, they may not be free-living.
“We’re not sure they can live independently, whether they have enough genes to fend for themselves, but instead are symbiotic with another organism or are feeding off another organism,” Baker said.
Baker now is trying to find the right conditions for these Archaea to thrive in a culture dish.