# A microbial growth curve # # The data are of an experiment in which the bacterium Lactococcus lactis was # grown in a culture in a microplate well. The optical density (OD) or light # scatter at 600 nm was measured for more than 60 hours. # # The background scatter of the medium has been subtracted from the data. # # The OD or scatter is roughly proportional to the biomass or number of cells # in the culture. We see an initial fast, exponential growth phase, which slows # down as the OD reaches a value of 0.5. A little later growth arrests and the # OD peaks sharply around 10 hours. The decrease of OD after 10 hours is not # well understood. It may be caused by several factors like lysis of cells, the # formation of long chains and precipitation of cells to the bottom of the # well. We assume that the maximal OD reached is indicative of the maximal # amount of biomass formed in the growth medium. time OD 0 0.002 0.25 0.0014 0.5 0.0014 0.75 0.0016 1 0.0021 1.25 0.0023 1.5 0.0029 1.75 0.0039 2 0.005 2.25 0.0064 2.5 0.0082 2.75 0.0105 3 0.0139 3.25 0.0178 3.5 0.023 3.75 0.0293 4 0.0377 4.25 0.0477 4.5 0.0617 4.75 0.0798 5 0.1021 5.25 0.1318 5.5 0.1684 5.75 0.2159 6 0.2679 6.25 0.3249 6.5 0.3944 6.75 0.4779 7 0.5432 7.25 0.6027 7.5 0.6768 7.75 0.7506 8 0.8324 8.25 0.8952 8.5 0.9436 8.75 0.9672 9 0.9818 9.25 0.997 9.5 1.0132 9.75 1.0218 10 1.0208 10.25 1.0153 10.5 1.0124 10.75 1.0066 11 1.0062 11.25 0.9976 11.5 0.9939 11.75 0.9925 12 0.9886 12.25 0.9889 12.5 0.9807 12.75 0.9801 13 0.9812 13.25 0.9755 13.5 0.9737 13.75 0.9658 14 0.9672 14.25 0.9627 14.5 0.9658 14.75 0.9604 15 0.9605 15.25 0.9593 15.5 0.9497 15.75 0.9488 16 0.9447 16.25 0.9419 16.5 0.9437 16.75 0.9394 17 0.9351 17.25 0.9303 17.5 0.9307 17.75 0.9241 18 0.9209 18.25 0.9181 18.5 0.9134 18.75 0.9092 19 0.9093 19.25 0.9023 19.5 0.8997 19.75 0.9 20 0.895