Nondividing, Bacteroid-Like Rhizobium trifolii: In Vitro Induction Via Nutrient Enrichment

James E. Urban
1979 Applied and Environmental Microbiology  
Rhizobium trifolii 0403 maintained in exponential phase via periodic dilution doubled in 210 min in mannitol-salts medium and doubled in 244 min in glycerolsalts. In both media, cell number and optical density increased in parallel. When exponentially growing cells in either medium were supplemented with a mixture of glucose, Casamino Acids, succinate, and yeast extract, optical density continued to increase but, within less than the time required for one doubling, division ceased. The increase
more » ... eased. The increase in optical density coupled with division cessation resulted in the formation of large, pleomorphic, nondividing cells. Large cells apparently increased in size as a result of swelling only at regions of most recent cell envelope synthesis. Greater than 95% of the cells in a population swelled, and commitment to swelling occurred within two doubling time equivalents. Swollen cells eventually reached a characteristic maximum size and exhibited osmotic fragility.
doi:10.1128/aem.38.6.1173-1178.1979 fatcat:rgc2fsmflbhwfccmy35lhfocri