EFFECT OF R-PLASMID-RP1 ON THE NUTRITIONAL-REQUIREMENTS OF ESCHERICHIA-COLI IN BATCH CULTURE

The minimal nutritional requirements of E. coli have been quantitively determined in batch culture for cells with (R+) and without (R-) the R plasmid RP1. In these conditions R+ cells have a greater requirement than R- for several nutrients, particularly Mg2+, K+, Fe2+ and PO43-. The maximum growth rate in a simple salts medium was the same for R+ and R- cells. At low concentrations of phosphate, the specific growth rate of R+ cells differed from that found for R- cells. The R plasmid was stable in simple salts medium, irrespective of the nutrient ultimately depleted by growth, but, on storage, R+ cells survived for a shorter time than R- cells.