Table 2-2. Conditions under which polyhedral organelles are formed Growth conditions Aerobic or anaerobic Polyhedra formation Succinate/PD Aerobic Yes Succinate/PD/B12 Aerobic Yes PD/B12 Aerobic Yes LB Aerobic No LB/PD Aerobic No Glucosea Aerobic No Glycerol Aerobic No Succinate Aerobic No Pyruvate/fumarate/PDb Anaerobic Yes PD/tetrathionateb Anaerobic Yes Glycerol/fumarate Anaerobic Rare Glycerol/tetrathionate Anaerobic Rare Glucosea Anaerobic No Pyruvate/tetrathionateb Anaerobic No Pyruvate/fumarate/tetrathionateb Anaerobic No Pyruvate/fumarateb Anaerobic No aResults provided by Dr. Thomas Bobik. bResults provided by Robert Busch. was during aerobic growth on a mixture of succinate and PD or during anaerobic growth on a mixture of pyruvate, fumarate, and PD. Anaerobic growth on succinate/PD minimal medium was not performed since S. enterica is unable to metabolize succinate anaerobically. To determine if catabolism of PD is a prerequisite for polyhedral organelle formation, aerobic growth of S. enterica on succinate/PD minimal medium was conducted in both the presence and absence of CN-B12. Under aerobic conditions without CN-B12 supplementation, S. enterica is unable to catabolize PD since de novo synthesis of B12 occurs only under anaerobic conditions (Miuller et al. 1990, Miuller et al. 1991). Polyhedral organelles were observed in cells under both conditions indicating that the catabolism of PD is not required for the formation of the polyhedra organelles in S. enterica. Polyhedral organelles were not formed on LB medium supplemented with