00:01
This is a typical microbiological problem.
00:04
We have to calculate the concentration of bacterial cells in initial flask.
00:13
And we make dilutions with different volume of diluent and then inoculate 0 .1 militer of each dilution into the appropriate nutrient medium.
00:25
And after incubation we obtain such results as 25 colonies, 180 colonies and two numerals to count in other plates.
00:40
So for solving this problem first of all let's mark test tubes.
00:46
Here will be first, second, third and fourth.
00:53
And let's calculate the dilution in each test tube.
00:59
Dillusion in the first test tube will be total volume 1 milliliter plus 9 milliliters divided by the volume that was diluted 1 milliliter and we obtain 10 so the first dilution will be 1 to 10 or 10 in power minus 1.
01:34
Next the same dilution so here will be 1 to 10 and the whole dilution will be 10 in power minus 2 dilution in the third test tube let's calculate in the third the total volume of 1 1 militer plus 99 militers divided by 1 milliliter and we obtain 100 so the dilution in the third test tube is 1 to 100 and the total dilution will be 10 in power minus 4 and the last test tube 1 2 10 10 in power minus 5.
02:37
Next, we know the rule that as a result we choose the plate that contains from 30 to 300 colonies.
02:53
So we have to use this plate for calculation of bacterial concentration.
03:01
We see that the concentration of bacteria in test tube number 3 is 100...