Dandekar & Chandler:Casein growth experiments: Difference between revisions
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''for 1000 mL'' | ''for 1000 mL'' | ||
''Requires flushing with inert gas'' | ''Requires flushing with inert gas if using for anaerobic experiments (steps 1-4)'' | ||
800 ml ddH2O | 800 ml ddH2O | ||
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- Autoclave for 45 min | - Autoclave for 45 min | ||
For anaerobic experiments: | |||
1. Pour PM into round flask, flush with argon gas for 30 min, close with rubber stopper, and place medium and 16 ml [http://www.chemglass.com/product_view.asp?pnr=CLS-4208 hungate tubes] (including lids and rubber stopper) into anaerobic glove box | 1. Pour PM into round flask, flush with argon gas for 30 min, close with rubber stopper, and place medium and 16 ml [http://www.chemglass.com/product_view.asp?pnr=CLS-4208 hungate tubes] (including lids and rubber stopper) into anaerobic glove box | ||
Revision as of 11:02, 6 March 2014
Back to Protocols
Casein growth FYIs
- 1% casein medium is somewhat opaque, but this is not why OD cannot be used as a measure of growth
- As pseudomonas elastase/proteases break down casein, the turbidity in the tube increases as the bits of degraded protein accumulate
- -- WT PAO1 will turn the tube milk white and completely opaque after ~4 hours after the first few days of passage into fresh medium
- -- A LasR mutant should NOT show the milky tube phenotype! If it does, you have contamination
- if you want to keep the casein solution you have made, be sure to keep a negative control to rule out contamination there
- To enumerate growth, colony counts should be performed
Casein media recipes
1% casein medium
1% Casein sodium salt from bovine milk [from Sigma]
1x PM medium or 1x M9
- Stir at medium high speed until casein is dissolved (can take anywhere from 1-3 hours depending on how awesome your stir plate is)
- Filter sterilize
- -- Note that filter surface area is the same size in the 250 ml and 500 ml filter sterilization units; because the filters will clog, it's better to aliquot into 250 ml or smaller bottles
PM Medium
for 1000 mL
Requires flushing with inert gas if using for anaerobic experiments (steps 1-4)
800 ml ddH2O
25 ml 0.5M Na2HPO4
25 ml 0.5M KH2PO4
10 ml 10% (NH4)2SO4
10 ml concentrated base (recipe follows)
- Bring volume to 1000 ml and pH to 6.8
- Autoclave for 45 min
For anaerobic experiments: 1. Pour PM into round flask, flush with argon gas for 30 min, close with rubber stopper, and place medium and 16 ml hungate tubes (including lids and rubber stopper) into anaerobic glove box
2. Pour 10 ml into hungate tubes, and close with rubber stopper and lid
3. Remove tubes from glove box and autoclave
4. Add carbon sources from sterile stock solutions (e.g., acetate and succinate)
Concentrated base for PM
for 1000 mL
Casein growth protocols
Starting casein cultures
4 days before the start of experiment
- From frozen stock, streak to LB plate and grow O/N at 37°C
3 days before
- Pick a single colony and inoculate into LB + 5mM MOPs buffer
- Grow O/N at 37°C with shaking
2 days before
- Into an 18 mm tube with 3 mL 1% casein, transfer 30 μL O/N LB culture (Day 1 casein culture')
- Grow O/N at 37°C with shaking
1 day before
- Into fresh 1% casein, transfer 100 μL from Day 1 casein culture to start Day 2 casein culture
- Grow O/N at 37°C with shaking
Use this Day 2 culture to set up casein experiments