Agrobacterium tumefaciens Conn. 3. Effect of thermal shock on bacteria in relation to tumorinducing ability.

Stonier, Tom (Manhattan College, Bronx, N.Y.), Robert E. Beardsley, Lowell Parsons, and James McSharry. Agrobacterium tumefaciens Conn. III. Effect of thermal shock on bacteria in relation to tumor-inducing ability. J. Bacteriol. 91:266-269. 1966.-Bacteria heated to 42 C for 30 min exhibit a decrease in tumor-initiating ability without a detectable loss in viability. The thermal shock inhibits subsequent bacterial growth for up to 1.5 hr. As bacterial growth recovers, so does tumor-initiating ability. Respiration of the culture is somewhat increased by the heat treatment. The data suggest that living, actively respiring bacteria do not induce tumors unless they are also growing. The results also point to the necessity for excluding bacterial growth inhibition when interpreting data on the effect of various agents on tumor initiation.