The effect of different seawaters on survival and growth of biotin-, isoleucine-, and uracil-requiring mutants of the marine bacterium, Serratia marinorubra, has been investigated. Samples of seawater were collected from coastal waters, the California Current, and central North Pacific waters at depths of 1, 25, 50, 100, 250, and 500 m. The growth or survival of the test bacterium in basal medi...