Time Growth curve (liquid medium inoculated with 1,000,000 cells at time O hrs)

Question

Time Growth curve (liquid medium inoculated with 1,000,000 cells at time O hrs) (hrs) CFU/mL 0 1.00E+06 1.E+10 8 1.04E+06 16 1.04E+06 24 1.06E+06 32 1.50E+06 40 4.00E+06 48 1.60E+07 56 6.40E+07 64 2.56E+08 72 1.02E+09 80 2.46E+09 88 2.84E+09 96 2.89E+09 104 2.84E+09 112 2.89E+09 120 2.92E+09 1.E+09 1.E+08 1.E+07 1.E+06 1.E+05 0 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 Time (hours) Question 26 The data in the table above and plotted on the right are viable plate counts obtained from a bacterial culture inoculated at time = 0 and incubated for 180 hours. 26-C. Using the data above and the equation N - N x 2", where n is the number of generations (n -t/g) estimate the generation time of this microbe under these conditions. (4 pts) OI 7.ao .02x1o" n=log(1o2x10?)-log C 1.60x10 . 30 1 301 le.olg. 24.. 6.0 601 3.9 hrs t: 2 26-D. Approximately how long would be required for a single cell on an agar plate to grow into a colony that would be visible by the naked eye (assume 10 cells in a barely visible colony)? (2 pts) 778 1111141621222222 642086 123445 2086 7889

Explanation / Answer

Generation time is time taken by bacteria (cell) to divide into two cells. After one division the number goes to 2 after 2 it goes to 4. Hence the formula for number of bacterial cells is,

Number of bacterial cells = 2n where n is number of generations.

Barely visible colony number is 106.

Therefore, 106 = 2n. Therefore n = 6/log2 = 19.93 approx. We can round it up to 20 generations or can keep it 19.93.

Total time required = generation time X number of generations = 3.9 hours X 19.93 = 77.73 hours.

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