After the Fall, Before the Fall, During the Fall

APRIL 2014

The sheep pasture high in New Zealand hills lay thick in white clover. One corner of the pasture had been planted with chicory, but the clover grew wild. Low, white-flowered, sweet-smelling, it attracted the bees buzzing above the fenced pasture. Sheep munched contentedly, flicking their tails. Beside the fence, two lambs chased each other.

The clover’s root system, fibrous and fast-growing, laced itself through the soil. The original tap root extended three feet deep; branches clustered thickly near the top grew, in turn, a mass of fine rootlets. Much of the system was slimed with new bacteria, created by a long chain of plasmid swaps. There had been more than enough candidates for this gene-swapping: a teaspoon of the sheep pasture’s soil contained over 600 million bacteria. The new anaerobic strain included a gene that broke down carbohydrates, producing carbon dioxide and alcohol.

The alcohol accumulated on the plant roots. In a short time the fermentation had deposited ethanol on the plant roots in a concentration of one part per million. When the concentration reached twice that, the clover began to die.

The new bacteria went on multiplying. A ewe munched up a handful of clover, jostling the root system so that it touched another. The ewe ambled on toward her lamb.