Practice question

Balanced exponential growth implies each cell divides into two, so number after one generation doubles. In log phase cultures specific growth rate constant, generation time minimal, cells divide asynchronously but average population doubling per generation time. Starting N0, after n generations N equals N0 times two to n. Therefore per generation increase factor exactly two, not one meaning no growth, nor four or eight which would imply multiple fission or formation of tetrads and octads seen in some cocci Sarcina but not typical rods Escherichia coli bacilli dividing by binary transverse fission via divisome septation at midcell. Factor two verified by cell counts and optical density doubling within generation interval. Understanding twofold increase underpins logarithmic plotting, calculation mu equals ln2 over g, and concept that small inoculum amplifies enormously ten generations thousand fold, twenty generations million fold. This explains why contamination control critical and why selective enrichment can amplify rare pathogens rapidly during incubation, also forms basis for quantitative models of population expansion in microbial ecology and infection kinetics.