1why did you set the wavelength of the spectrophotometer at

1)why did you set the wavelength of the spectrophotometer at 595 nm when you measure OD of the E.coli culture?

2)what difference do you expect to see between the colonies on the LB agar plate and the colonies on the GMS plate?

Solution

When measuring light scattering it is important to consider the wavelength of light used a bacterial culture. Microorganisms may contain numerous macromolecules that will absorb light, including DNA (254 nm), proteins (280 nm), cytochromes (400-500 nm), and possible cell pigments. When measuring bacteria by light scattering it is best to pick a wavelength where absorption is at a minimum and for most bacterial cultures wavelengths around 595 nm are a good choice. However, the exact wavelength chosen is species specific.Therefore, it is best to pick a wavelength where absorption is at a minimum.

The LB (Luria-Bertani) broth is both food and water for the bacteria. It will help make the bacteria healthy after poking holes in them, shoving DNA into them. Now the bacteria can become metabolically active and begin making proteins, specifically the amp resistance gene, which they will need this protein before being placed into the environment of Ampilcillian.