The discovery of complex organic molecules on Saturn’s moon Enceladus raises the question:What about introducing organisms from Earth, even if none exist out there now? From Laurie Fickman at the University of Houston:
In professor George Fox’s lab at the University of Houston, scientists are studying Earth germs that could be contaminating other planets. Despite extreme decontamination efforts, bacterial spores from Earth still manage to find their way into outer space aboard spacecraft. Fox and his team are examining how and why some spores elude decontamination. Their research is published in “BMC Microbiology.”
To gain access into the uber-sanitized clean rooms at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the world’s largest clean room, or the Jet Propulsion Laboratory in Caltech, California, employees pass through a series of lobbies. One, with adhesive floor mats, traps dirt carried on shoes. Another, about the size of an old phone booth, delivers a forced-air shower where dozens of air jets blow away dirt and debris. Only after these sterilization measures can they don the bodysuits, head covers and other disinfected regalia.
And still, bacteria survive and have been carried onboard the International Space Station and found on the Mars Rover. The ability of bacteria to survive extreme conditions could potentially lead to a process called ‘forward contamination.
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“It is quite possible that distinctions in gene regulation can alter the expression levels of key proteins thereby changing the organism’s resistance properties without gain or loss of a particular gene. These are potential genes of interest with respect to the resistance of the spores of this strain” said Tirumalai.
As it turns out, four of these genes are found on phage elements of the bacterial strain. Phage, short for bacteriophage, is a virus that infects bacteria. Phages are major facilitators for transferring genes between microbes. More.
Conclusions: It is not immediately obvious that the presence or absence of any specific gene or combination of genes is responsible for the variations in resistance seen. It is quite possible that distinctions in gene regulation can alter the expression levels of key proteins thereby changing the organism’s resistance properties without gain or loss of a particular gene. What is clear is that phage elements contribute significantly to genome variability. Multiple genome comparison indicates that many strains named as B. pumilus likely belong to the B. safensis group. (open access) – Madhan R. Tirumalai, Victor G. Stepanov, Andrea Wünsche, Saied Montazari, Racquel O. Gonzalez, Kasturi Venkateswaran, George E. Fox. Bacillus safensis FO-36b and Bacillus pumilus SAFR-032: a whole genome comparison of two spacecraft assembly facility isolates. BMC Microbiology, 2018; 18 (1) DOI: 10.1186/s12866-018-1191-y Abstract More.
Future headline: We have met the aliens and they are our bugs.
See also: Complex organic molecules found on Saturn’s moon Enceladus. At this point, it will be just as interesting if Enceladus has “all of the basic requirements for life as we know it” but does not have life. That would cast doubt on the thesis that life naturally evolves when the conditions are right. Of course, we will need quite a few examples to be sure.
Looking for life in all the hard places – a guidebook Researcher: “We are using Earth to guide our search for life on other planets because it is the only known example we have,” said Timothy Lyons, a distinguished professor of biogeochemistry and director of the Alternative Earths Astrobiology Center.
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Could alien life be buried in ET oceans?