These are derived forms of bacteria that are adapting to artificially stringent environmental conditions, and they were found in a geologically young lake so no, this is not the bacterium primeval.

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Yet there are no substantiated reports of antibiotic-resistance genes jumping from a plant to a bacterium.

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Specifically they discovered that Pythium ultimum, a fungus that attacks aubergines, peppers, lettuces, tomatoes and cucumbers as seedlings, Clavibacter michiganensis, a bacterium that kills young plants and deforms fruits, and Streptomyces scabies, a second bacterium, which causes potatoes to develop revolting scabs and for which no treatment currently exists, all stopped growing in the presence of the oil.

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Before now, Dr Clarke told the BBC, the bacterium being studied had been seen influencing levels of minerals in lakes and seas but no-one really knew how it did it.

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