Table of Contents
Why is a wavelength of 600 nm used to measure growth of bacteria could another wavelength be used?
600 is traditionally used because you are looking for optical density which is proportional to the number of bacterial cells in the cuvette. Alternative wavelengths can also be used if the bacterium displays a specific chromophore.
Why do we use 600 nm to measure absorbance?
Cells of many bacteria are almost colorless and real light absorption is marginal. OD600 is preferable to UV spectroscopy when measuring the growth over time of a cell population because at this wavelength, the cells will not be killed as they would under too much UV light.
What is typically measured using a spectrophotometer set at a wavelength of 600 nm?
The turbidity measurement of microbial cultures is a commonly used method to determine the growth phase or cell number in an actively growing culture. Most often, these determinations are done using a spectrophotometer to measure the absorbance at 600 nm.
What is 600 nm wavelength?
Red light has a wavelength of about 600 nm.
How is od600 calculated?
Expected OD 600 is determined by counting cell number using an alternative technique (for example microscope slide method) and converting to OD 600 using the rule of thumb that 1 OD 600 = 5 x 108 cells/ml for E. coli.
What are the phases of bacteria?
Bacterial colonies progress through four phases of growth: the lag phase, the log phase, the stationary phase, and the death phase. The generation time, which varies among bacteria, is controlled by many environmental conditions and by the nature of the bacterial species.
How is OD600 calculated?
Difference in OD600 Readings Expected OD 600 is determined by counting cell number using an alternative technique (for example microscope slide method) and converting to OD 600 using the rule of thumb that 1 OD 600 = 5 x 108 cells/ml for E. coli.
What color has a wavelength of 600 nm?
Spectral colors
| Color | Wavelength (nm) | Frequency (THz) |
|---|---|---|
| green | 500–565 | 530–600 |
| yellow | 565–590 | 510–530 |
| orange | 590–625 | 480–510 |
| red | 625–700 | 400–480 |
How full should you fill a cuvette?
Fill the cuvette about 3/4 full of the solution you wish to test. Wipe the outside of the cuvette with a lint-free, soft tissue (a Shurwipe or and Accuwipe) to remove any moisture or fingerprints from the outside surface.
Does cuvette size affect absorbance?
The absorbance is directly proportional to the length of the light path (l), which is equal to the width of the cuvette.
What Colour is 470 nm?
Blue
Physics of color
| Color | (nm) | (eV) |
|---|---|---|
| Cyan | 500 | |
| Blue | 470 | 2.64 |
| Violet (visible) | 420 | 2.95 |
| Near ultraviolet | 300 | 4.15 |
What color is light at 500 nm?
The colors of the visible light spectrum
| colour | wavelength interval | frequency interval |
|---|---|---|
| yellow | ~ 565–590 nm | ~ 530–510 THz |
| green | ~ 500–565 nm | ~ 600–530 THz |
| cyan | ~ 485–500 nm | ~ 620–600 THz |
| blue | ~ 440–485 nm | ~ 680–620 THz |