Calculating Maximum Specific Growth Rate ($\mu_{max}$)
The maximum specific growth rate ($\mu_{max}$) represents the maximum rate at which a microorganism population increases under optimal conditions during its exponential growth phase.
The relationship between biomass ($X$) and time ($t$) during exponential growth can be expressed logarithmically. By taking the natural logarithm (ln) of the biomass concentration, we get:
$ $ \ln X = \mu t + \ln X_0 $ $
Where:
- $X$ is the biomass concentration at time $t$.
- $X_0$ is the initial biomass concentration at $t=0$.
- $\mu$ is the specific growth rate.
- $t$ is the time.
This equation is in the form of a linear equation ($y = mx + c$), where:
- $y = \ln X$
- $x = t$
- The slope ($m$) is the specific growth rate ($\mu$).
- The y-intercept ($c$) is $\ln X_0$.
Determining $\mu_{max}$
To find the maximum specific growth rate ($\mu_{max}$), we need to determine the slope of the plot of ln X versus t specifically during the exponential growth phase. This phase is characterized by a constant and maximal specific growth rate.
Therefore, the correct method is calculating the slope of the $\ln X$ versus $t$ curve during this specific phase.
Important Questions from Kinetics of Cell Growth
- In the process of generating a clonal mammalian cell line, a single cell was seeded in a well of a cell culture plate. After the first 48 hours, one of the progeny cells underwent apoptosis due to a new mutation. If the doubling time of the cells is 24 hours and no more cell death occurs, the total number of cells after a total of 7 days from seeding will be ______. (answer in integer)
- A synchronous culture containing $1.8 \times 10^5$ monkey kidney cells was seeded into three identical flasks. The doubling time of these cells is 24 h. After 24 h, the cells from all the three flasks were pooled and dispensed equally into each well of three 6-well plates. The number of cells in each well will be ________ $\times 10^4$.
- Which one of the following is NOT used for the measurement of cell viability in animal cell culture?
- A T-flask is seeded with $10^5$ anchorage-dependent cells. The available area of the T-flask is $25 \text{ cm}^2$ and the volume of the medium is $25 \text{ ml}$. Assume that the cells are rectangles of size $5 \text{ µm} \times 2 \text{ µm}$. If the cells grow to monolayer confluence after $50 \text{ h}$, the growth rate in number of cells/($\text{cm}^2.\text{h}$) is _________ $ \times 10^5$.
- Determine the correctness or otherwise of the following Assertion (a) and the Reason (r) Assertion: In synchronous culture, majority of the cells move to next phase of the cell cycle simultaneously. Reason: Synchronous culture could be obtained by starving cells for essential nutrient components.
