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 bacteria from deep-sea vents with those of human and animal bacterial pathogens. Their evolutionary relationship suggests that animal pathogens came from the deep.

Life on the ocean floor may have provided bacteria with the survival strategies to cope with life as pathogens, says Satoshi Nakagawa of the Japan Agency for Marine-Earth Science and Technology, Yokosuka, whose team carried out the analysis.

Deep-sea or hydrothermal vents spew superheated water, rich in chemicals, from volcanically active mid-ocean ridges. Here, bacteria feeding on methane and sulphides support large communities of exotic animals.


The study found that 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 extreme temperature changes in these environments.

The ability to survive in an ever-changing environment is also useful for pathogens under attack from their host’s immune system. The team suggests that the bacteria initially lived with vent invertebrates before swapping that location for life as a pathogen.

Nakagawa says he does not know how the bacteria jumped from the deep sea to the human body “The best answer might come from the fossil record,” he says.

Mysteries of the Deep Sea – The deep sea is one of the harshest habitats on Earth, but is home to many remarkable creatures. Learn more in our comprehensive special report.

Journal reference: Proceedings of the National Academy of Science (DOI: 10.1073/pnas.0700687104)