For calculation of the generations in broth medium, I determine the initial number of bacteria and then the final number of them in a given time. Afterwards, by using the formula, I can determine the generations.
Now I would like to know the method to determine the number of generation in a solid culture medium.
Bacterial growth in solid environment could be studied with microcalorimetric analysis.
please see the following paper:
Microcalorimetric study of the growth of bacterial colonies of Lactococcus lactis IL1403 in agar gels.
Kabanova N, Stulova I, Vilu R. Food Microbiol. 2012 Feb;29(1):67-79. doi: 10.1016/j.fm.2011.08.018.
by counting, by turbidimetry or by flow cytometry.
p'se us these key words in google for more details.
Unless, contact again on [email protected]
regards,
I think it is not possible to do this determination in solid medium. For achieved this you should count the number of bacteria every hour on the plate for example. Maybe taking a picture, but you would have much error accompanied, even if to make a densitometry analysis of the photo, and you would have to do a calibration curve to know how many cells correspond to a pixel for example. I work with yeast and never saw that parameter determined in plates. Also, the generation time is generally measured in the exponential growth phase, in this phase the cell growth is constant, as well as the duplication of cells. In solid medium cells rapidly deplete their immediate resources and one of the criteria in the exponential phase growth is that none of the nutrients are limited.
Solid culture medium - are you refering to growth on selected agar medium?
Resuspend a single colony in a suitable medium, count the cells by whatever method you prefer, and run the same calculation as for growth in exponential phase in liquid media, assuming that the initial number of cells is 1.
Not ideal, but may suit you depending on what you want.
I suggest grow you bacteria on a membrane (e.g, polycarbonate, pore size 0.2 um) laid on the agar medium. Before the experiment, the membrane should be autoclaved or UV sterilized. To count the bacteria, remove the membrane, detach the bacteria and suspend in liquid medium and do plate counting, flow cytometery, or protein measurement.
Dear Rasoul!
Hi! It is the same method as in liquid medium. But as your culture was made on solid medium, you will, prior to begin yr biomass determination, dilute all colonies in peptone solution for example. Remember that yr calculation of g is carried out in exponential phase.
Regards,
I would never recommend to do this, but if liquid media are not an option, you could try the following. The number of colonies on the plate are of no concern to determine the growth rate. What you could try is to measure the speed at which a colony doubles its surface. Measure the surface under a microscope of an upcoming colony and measure during some appropriate time interval. The surface is a measure of doubling time. Far from ideal, but maybe an acceptable approximation. (Please do this for several colonies and take an average/standard deviation)
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