Scientists brave ‘world’s worst water’ to watch wild bacteria evolving

For almost a decade, Jillian Banfield has been travelling to a place that “pushes the limits of human endurance” – Richmond Mine in Northern California. Its abandoned caverns can reach 48 degrees Celsius and 100 per cent humidity. They are low in oxygen. They contain possibly the most acidic naturally occurring water on Earth, with a pH value of -3.6. But even in these conditions, there is life. Bacteria grow within the cave, floating in thin films on top of its hot, acidic water. They are the lords of their extreme world, and they provide an unrivalled opportunity to study how wild microbes evolve. The mine ecosystem is extremely simple. The dominant species is a bacterium called Leptospirillum that lives in sulphuric acid and eats iron. Only a handful of other microbes share the mine, and most migrants would simply die. This is an ideal community for keen scientists – ...