A rare, recently discovered microbe that survives
on very little to eat has been found in two places on Earth: spacecraft
cleanrooms in Florida and South America.
Microbiologists often do thorough surveys of
bacteria and other microbes in spacecraft cleanrooms. Fewer microbes
live there than in almost any other environment on Earth, but the
surveys are important for knowing what might hitch a ride into space. If
extraterrestrial life is ever found, it would be readily checked
against the census of a few hundred types of microbes detected in
spacecraft cleanrooms.
The work to keep cleanrooms extremely clean knocks
total microbe numbers way down. It also can select for microbes that
withstand stresses such as drying, chemical cleaning, ultraviolet
treatments, and lack of nutrients. Perversely, microbes that withstand
these stressors often also show elevated resistance to spacecraft
sterilization methodologies such as heating and peroxide treatment.
"We want to have a better understanding of these
bugs, because the capabilities that adapt them for surviving in
cleanrooms might also let them survive on a spacecraft," says
microbiologist Parag Vaishampayan of NASA's Jet Propulsion Laboratory,
Pasadena, Calif., lead author of the 2013 paper about the microbe. "This
particular bug survives with almost no nutrients."
This population of berry-shaped bacteria is so
different from any other known bacteria, it has been classified as not
only a new species, but also a new genus, the next level of classifying
the diversity of life. Its discoverers named it Tersicoccus phoenicis. Tersi is from Latin for clean, like the room. Coccus, from Greek for berry, describes the bacterium's shape. The phoenicis
part is for NASA's Phoenix Mars Lander, the spacecraft being prepared
for launch in 2007 when the bacterium was first collected by
test-swabbing the floor in the Florida cleanroom.
Some other microbes have been discovered in a
spacecraft cleanroom and found nowhere else, but none previously had
been found in two different cleanrooms and nowhere else. Home grounds of
the new one are about 2,500 miles apart, in a NASA facility at Kennedy
Space Center and a European Space Agency facility in Kourou, French
Guiana.
A bacterial DNA database shared by microbiologists
worldwide led Vaishampayan to find the match. The South American
detection had been listed on the database by a former JPL colleague,
Christine Moissl-Eichinger, now with the University of Regensburg in
Germany. She is first co-author of the paper published this year in the International Journal of Systematic and Evolutionary Microbiology identifying the new genus.
The same global database showed no other location
where this strain of bacteria has been detected. That did not surprise
Vaishampayan. He says, "We find a lot of bugs in cleanrooms because we
are looking so hard to find them there. The same bug might be in the
soil outside the cleanroom but we wouldn't necessarily identify it there
because it would be hidden by the overwhelming numbers of other bugs."
A teaspoon of typical soil would have thousands
more types of microbes and billions more total microbes than an entire
cleanroom. More than 99% of bacterial strains, as identified from DNA
sequences, have never been cultivated in laboratories, a necessary step
for the various types of characterization required to identify a strain
as a new species.
Microbes that are tolerant of harsh conditions become more evident in cleanroom environments that remove the rest of the crowd.
"Tersicoccus phoenicis
might be found in some natural environment with extremely low nutrient
levels, such as a cave or desert," Vaishampayan speculates. This is the
case for another species of bacterium (Paenibacillus phoenicis)
identified by JPL researchers and currently found in only two places on
Earth: a spacecraft cleanroom in Florida and a bore hole more than 1.3
miles deep at a Colorado molybdenum mine.
Ongoing research with Tersicoccus phoenicis
is aimed at understanding possible ways to control it in spacecraft
cleanrooms and fully sequencing its DNA. Students from California State
University, Los Angeles, have participated in the research to
characterize the newly discovered species.Posted by NASA
Posted by Tim Sandle
