In the Gulf of Mexico, nature’s janitors are hard at work, mopping up the aftermath of a man-made disaster. On 20 April, 2010, an explosion at the Deepwater Horizon rig unleashed the largest oil spill in US history. Now, a team of American scientists led by Terry Hazen have shown that just a month or so after the incident, a microscopic clean-up crew had already started to digest the mess.

The ocean is home to many groups of bacteria that can break down the chemicals found in crude oil. Some, like Alcanivorax, are oil-eating specialists that are usually found in low numbers, only to bloom when oil spills provide them with a sudden banquet. That’s exactly what