Beta-galactosidase Screen: Difference between revisions
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<center>'''Making X-gal Plates'''</center> | |||
==Introduction== | |||
<center>These protocols are used to screen bacterial plates for [[beta-galactosidase]] activity using [[X-Gal]] (aka blue white screening). <br> Each of these protocols has its advantages and disadvantages so be sure to check which one works best for you.</center> | |||
==Materials== | |||
*X-gal Stock solution = 100mg/ml in dimethyl formamaide (DMF) | |||
*Agar | |||
*Media of your choice | |||
*Sterile water | |||
==Methods== | |||
===Making X-gal plates=== | |||
*This method is used if: you won't be keeping the plates more than a week, and the media has a neutral pH. | |||
*Colonies may take up to 36 hours to develop on these plates, but all positive colonies will be evenly colored. | |||
#Make the media according to your normal plate recipe and autoclave. | |||
#Let the media cool in a 60°C water bath. | |||
#Add X-gal stock solution at a ratio of 2μL per mL media (also add any antibiotic). | |||
#Swirl gently and pour immediately. | |||
#Once solid keep out of light. | |||
===Spread onto plates=== | |||
*This method is used if: you want to turn an existing plate into an X-gal plate, and the media has a neutral pH. | |||
*Colonies should develop color overnight, but due to uneven distribution of X-gal, all positive colonies may not be evenly colored. | |||
#Take a pre-poured plate and make sure it is dry (i.e. no condensation on the media) and solid. | |||
#Dilute the X-gal stock 1 to 1 with sterile water. | |||
#Pipette 50μL of this dilution onto the plate (If your plate has condensation on it skip the dilution and pipette 25μL of X-gal stock. | |||
#Evenly distribute the solution onto the plate using a spreader. | |||
#Let plate dry for 30mins at 37°C. | |||
===Agar Overlay=== | |||
*This method is used if: your media has a non-neutral pH, you forgot to do one of the other two protocols, or some undergrad in your lab mislabeled the plates. | |||
*Color should appear on fully developed colonies in 2-8 hours. | |||
#Microwave 10ml of water with 0.15g agar for each plate to be screened (e.g. for 10 plates it's 100ml water and 1.5g agar). | |||
#Let the molten agar cool in a 60°C water bath. | |||
#Add 2μL X-gal stock for each mL of molten agar (e.g. 200μL for 10 plates). | |||
#Pour 10 ml over each plate to be assayed. | |||
#Let solidify | |||
#Incubate plates in a dark place | |||
==See also== | |||
*[[Beta-galactosidase assay]] | |||
*[[LacZ staining of cells]] | |||
==References== | |||
[[Category:Protocol]] | |||
[[Category:In vitro]] | |||
[[Category:Protein]] |
Latest revision as of 11:52, 14 September 2011
Introduction
Each of these protocols has its advantages and disadvantages so be sure to check which one works best for you.
Materials
- X-gal Stock solution = 100mg/ml in dimethyl formamaide (DMF)
- Agar
- Media of your choice
- Sterile water
Methods
Making X-gal plates
- This method is used if: you won't be keeping the plates more than a week, and the media has a neutral pH.
- Colonies may take up to 36 hours to develop on these plates, but all positive colonies will be evenly colored.
- Make the media according to your normal plate recipe and autoclave.
- Let the media cool in a 60°C water bath.
- Add X-gal stock solution at a ratio of 2μL per mL media (also add any antibiotic).
- Swirl gently and pour immediately.
- Once solid keep out of light.
Spread onto plates
- This method is used if: you want to turn an existing plate into an X-gal plate, and the media has a neutral pH.
- Colonies should develop color overnight, but due to uneven distribution of X-gal, all positive colonies may not be evenly colored.
- Take a pre-poured plate and make sure it is dry (i.e. no condensation on the media) and solid.
- Dilute the X-gal stock 1 to 1 with sterile water.
- Pipette 50μL of this dilution onto the plate (If your plate has condensation on it skip the dilution and pipette 25μL of X-gal stock.
- Evenly distribute the solution onto the plate using a spreader.
- Let plate dry for 30mins at 37°C.
Agar Overlay
- This method is used if: your media has a non-neutral pH, you forgot to do one of the other two protocols, or some undergrad in your lab mislabeled the plates.
- Color should appear on fully developed colonies in 2-8 hours.
- Microwave 10ml of water with 0.15g agar for each plate to be screened (e.g. for 10 plates it's 100ml water and 1.5g agar).
- Let the molten agar cool in a 60°C water bath.
- Add 2μL X-gal stock for each mL of molten agar (e.g. 200μL for 10 plates).
- Pour 10 ml over each plate to be assayed.
- Let solidify
- Incubate plates in a dark place