Growth curves of selectively resistant strains of E. coli in monoculture with or without herbicide, antibiotic, or both
A, C: determination of the growth rate r of Strhigh/low (AH204/AH211) and Tethigh/low (AH201/AH214), respectively. The gray line represents log transformed OD600 values; the dotted black line represents our estimate of growth during the exponential phase calculated using log(OD) values between 48 and 150 min, the period between the grey dashed vertical lines. In this period log(OD) increased approximately linearly with time indicating exponential growth. B, D: determination of the carrying capacity k of Strhigh/low (AH204/AH211) and Tethigh/low (AH201/AH214), respectively. The gray line represents OD600 values; the dotted black line represents the estimated logistic curve calculated by fitting a logistic growth model using non-linear least squares. Antibiotics were used 0.25µg/mL for Str and 0.05µg/mL for Tet; herbicide concentrations were 1830 ppm ae Kamba and 311 ppm ae Roundup.