THE ROLE OF INTERCELLULAR FLUID AND BACTERIAL ISOLATE ON THE INVIVO PRODUCTION OF TABTOXIN AND TABTOXININE-BETA-LACTAM

In Woolley''s medium 17 isolates of tabtoxin-producing pathovars of Pseudomonas syringae produced tabtoxin. However, when the medium was supplemented with intercellular fluid from tobacco leaves, 14 of the isolates now produced tabtoxinine-.beta.-lactam rather than tabtoxin. At the time chlorosis first became evident in leaves infected by these isolates, only tabtoxinine-.beta.-lactam could be detected in the intercellular fluids, and no peptidase activity towards tabtoxin was detectable. Intercellular fluids from leaves infected by the 3 unusual isolates contained only tabtoxin. Depending upon the isolate, the intercellular environment can control which molecular form of the toxin is produced.