AGROBACTERIUM TUMEFACIENS: THERMAL INACTIVATION OF TUMOR-INDUCING ABILITY.

Treating cultures of Agrobacterium tumefaciens at 39 degrees to 48 degrees C reduces the infectivity of the bacteria without necessarily affecting viability. Destruction of the capacity to initiate tumor growth follows first-order kinetics from which rate constants for thermal inactivation are derived. From these rates, values for heat of activation of 56.7 kcal mole(-1) and entropy of activation of 107 cal mole(-1) deg(-1) are obtained. A particular protein or nucleoprotein active in the process of infection may be inactivated by the treatment.