Metabolic characterization of the viable, residually dividing and nondividing cell classes of recombination-deficient strains of Escherichia coli.

The abilities of rec+, recB- recC-, recA-, and recA- recB- rec C- strains to support growth of bacteriophage T4, to take up oxygen, and to maintain cell integrity have been measured. (i) With respect to bacteriophage T4 growth, T4 phage is produced with identical lysis time in single -step growth curves with all strains tested. rec- strains show reduced phage production (fewer infected centers), but the average burst size per infected center is the same for all strains tested. Some rec- cells are unable to produce any phage, whereas the remainder of the rec-cells produce phage as rapidly and as efficiently as rec+ cells. (ii) With respect to oxygen consumption, rec- strains are deficient relative to the rec+ control to the same extent as the deficiency in phage production by theculture. The reduction in oxygen consumption is coordinate with reduction in rate of mass increase of the rec- culture. (iii) With respect to cell integrity, rec- cultures show increased lysis as measured by release of beta-galactosidase into the medium. The kinetics of release suggest that rec- nondividing cells all eventually lyse. These results are most consistent with the idea that rec- residually dividing cells and viable cells are metabolically normal according to the parameters we have measured, whereas nondividing cells are metabolically inactive.