"G. coli": bacteria thrive in hypergravity

Bacteria can survive accelerations of 400,000g, making it highly likely that bugs could survive an interplanetary crash-landing aboard an asteroid, or even flourish on high-gravity massive planets, new research has revealed.

Previously, scientists have investigated the behaviour of bacteria under conditions of microgravity - usually in space - which has been show to boost bacterial growth rates, alter the patterns of genes that are expressed and also reduce the production of antibiotic molecules made by some microbial family members. But only a handful of studies have so far explored the reverse situation: exposure to high-g conditions.

Now though, thanks to Japan Agency for Marine-Earth Science-based researcher Shigeru Deguchi and his colleagues, this work has been done. Publishing their findings inPNAS, the team incubated a selection of microbes, including the bacterial species E. coli, in an ultracentrifuge to simulate gravitational accelerations of up to 403,000 times that felt at the Earth's surface.

Surprisingly, despite the extreme conditions, the bugs grew, albeit more slowly than they would do normally. And examining the resulting cells under the microscope revealed that they were structurally intact and resembled control bugs grown under more ideal conditions, despite the 126.5 megapascal pressure they would have felt.

The researchers also modelled how the distribution of molecules would be affected inside the bacteria under the high-g conditions. For the majority of modest-sized molecules, they found, the effect would be negligible with a less than 9% difference in concentration between one end of the cell and the other.

These results, say the team, suggest that, at one thousandth of a millimetre across, bacterial cells are small enough that irreversible deformation due to gravity is not significant to impact on their viability.

From a practical point of view, this suggests that altering the accelerative environment in which bacteria are grown - such as in fermenters - could be used to manipulate the metabolic profile of the cells, for instance to boost antibiotic or drug production in biotechnology settings.

But an even-more tantilising conclusion the researchers draw, however, is that since the deceleration associated with an asteroid impact would be in the order of 300,000g, and this is well within the survival-range for the bacteria studied in this set of experiments, the prospect for panspermia - the interplanetary transit of life aboard celestial bodies - becomes much more plausible...