Chocoholic germs can provide hydrogen, the clean-burning energy of the future, New Scientist reports.
British scientists fed Escherichia coli bacteria a diluted mix of waste caramel and nougat.
The germs tucked into the sugar and in the process produced hydrogen, using their own enzyme, called hydrogenase.
The hydrogen was used to power a fuel cell, generating enough electricity to drive a small fan.
The experiment has applications far beyond the lab.
Waste chocolate, instead of being thrown away by confectionary companies, could be turned into hydrogen and used to help power their factories or sold to energy companies.
The British team, led by Lynne Mackaskie at the University of Birmingham, central England, got the same bacteria to tuck into catalytic converters from old cars.
The bacteria cleverly recovered the precious metal palladium after they were immersed in a vat with hydrogen and liquid waste from spent converters.
The work is reported in full in the specialist journal, Biochemical Society Transactions.