Practice question

Generation time defines kinetic metric of prokaryotic proliferation, interval required for population to double in cell number during balanced growth. Since bacteria propagate by binary transverse fission, each mother cell splits into two genetically identical daughters after chromosome replication, partition via ParABS, and septal wall formation by divisome. Therefore cell number doubling corresponds to one complete cell cycle. During exponential phase generation time g remains constant, specific growth rate mu equals 0.693 over g. Values vary dramatically: Vibrio natriegens fastest known 10 minutes, Escherichia coli 20 minutes in Luria broth at 37C, Bacilus subtilis 30 minutes, Mycobacterium tuberculosis 18 hours, Mycobacterium leprae days. Medium richness, temperature near optimum, aeration, pH influence g. Measuring g via viable counts plotting log CFU versus time allows calculation of growth yield, prediction of contamination load in food safety, optimization of starter cultures, and assessment of fitness costs associated with antibiotic resistance mutations altering ribosomal or division kinetics.