Time Magazine (Monday, Oct. 05, 1959)
Bugs in the Reactor

Los Alamos' Omega West is a swimming-pool-type research reactor whose fuel rods are suspended under 25 ft. of water, which acts not only as coolant and moderator but also shields its human operators from radioactivity. In the spring of 1958, physicists peering down through it saw that the water was getting cloudy. They called Chemist-Bacteriologist Eric B. Fowler of the laboratory's radioactive-waste disposal group, who found that it was swarming with microorganisms, about 1 billion per quart. The bugs turned out to be rod-shaped bacteria of the genus Pseudomonas, which were feeding on resin and felt in the water purifying system.

The fierce radiation in the reactor appeared to bother the bacteria hardly at all. When the reactor was shut down but still highly radioactive, they multiplied fast. Even when it was running full blast, they held their own. Since they normally divide every 20 minutes or so, this meant that radiation was killing only about as many as managed to live and divide. Just how much radiation the Pseudomonas got is hard to estimate, because the water circulates at varying distances from the core of the reactor, but Dr. Fowler thinks they may have absorbed more than 10 million rep (roentgen equivalent physical) in an eight-hour day, which is 10,000 times the dose that is fatal to man.

Many other microorganisms must have got into Omega West's deadly water; only the Pseudomonas survived. Perhaps the Pseudomonas have natural resistance to radiation. More likely, under the bombardment of Omega's radiation, normal Pseudomonas underwent mutation, producing a special strain capable of surviving in this atomic blast.

This ability to transform themselves quickly to cope with new conditions is a specialty of humble bacteria, whose constitutions are relatively simple. It is an ability that higher animals cannot emulate, but may have reason to envy.

Raloff: Reactor Bugs (1998)