Question

Table 2 (1): Bacterial abundance and absorbance of suspensions of E.coli - class data. (Average the class data and put the numbers in here). Test tube Bacterial abundance (CFU/mL) Absorbance (660nm) 0.9441 6.7.27 2. 27x10 1398109 9.27x108 6.537 0.371 0.273 01186 7.loxlu 8 4.80x108 2.76x108 Figure 2 [2]: Standard curve with the class data. Plot Absorbance versus Bacterial Abundance (CFU/ml using table 2. Graphs must be hand-drawn (not computer generated). Draw a best-fit line. on 50

if my optical density was 0.032 what would be the bacterial aboundance based on the plot

Answer 1

To answer this question, first you need to plot a bacterial concentration versus absorbance graph.

Bacterial population Vs. absorbance Absorbance 5 10 15 20 Bacteria CFU per ml (*10^8)

Then you need to extrapolate the graph as follows -

Bacterial population Vs. absorbance Absorbance 5 6.5 x 10^8 10 15 20 Bacteria CFU per ml (*10^8)

I think you have mistaken. 0.032 is a very less value and it have a very less number of bacterial cells. 0.032 should be correct. And if this is the value, then the data which you have given, is invalid.

So I have extrapolated the graph by using 0.32. At this OD, concentration will be 6.5 × 10^8 CFU per ml.

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