The bacterium Pseudomonas protegens, a plant cohabitant, uses injectio ns of toxic protein to kill soil pathogenic bacteria and fungi eating the root system of plants. Poison of pseudomonad destroys one of the key compounds necessary for almost any cell. This substance is a coenzyme involved in many oxidation-reduction reactions, and its destruction leads to the death of the organism. Exploring the genetic mechanisms of such a "military strategy", scientists found that many bacteria have similar genes coding for specifically-targeted toxins.