WHAT is the difference between the bacteria around a deep-sea vent and those in the human body? Surprisingly little, according to a comparison of the genomes of non-pathogenic bacteria from deep-sea vents with those of human and animal bacterial pathogens.
Their evolutionary relationship suggests that animal pathogens came from the deep (, DOI: 10.1073/pnas.0700687104).
Life on the ocean floor may have provided bacteria with the survival strategies to cope with life as a pathogen, says Satoshi Nakagawa of the Japan Agency for Marine-Earth Science and Technology, Yokosuka, whose team carried out the analysis. Vent bacteria frequently lose genes, develop new mutations or acquire genes from evolutionarily distant sources. That is an advantage when dealing with the steep chemical gradients and temperature changes at deep-sea vents.
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The ability to survive in an ever-changing environment is also useful for pathogens under attack from their host鈥檚 immune system. The team suggests that the bacteria initially lived with vent invertebrates before swapping symbiosis for life as a pathogen.
Nakagawa says he has no idea how the bacteria jumped from the deep sea to the human body. 鈥淭he best answer might come from the fossil record,鈥� he says.
