Biofilm formation test
Reagents:
- Staphylococcus aureus solution (37℃, 200rpm, overnight culture)
- Anti-microbial peptides stock solutions (1mg/ml) (or AMPs: LL-37, Grammistin-Pp1, GF-17) (China Peptides, Suzhou)
- LB Broth
- 96-well transparent plate
Procedure:
- Dilute 200μl Staphylococcus aureus of stationary phase to 2ml volume using LB.
- Mix 100 μl diluted S. aureus (in step 1) and 100 μl peptide solutions of different concentrations and transfer the mixture in 96-well plate.
- Add 200μl LB to each well in column 1 of both plates.
- Add 20μl S. aureus (from step 2) and 180μl LB to each well in column 2 of both plates.
- Add 200μl S. aureus+AMP solution (from step 3) to wells 1-4, 5-8 in column 3,4,5,6,7,8,9,10,11,12 (4 repeats for each concentration of AMP).
- Seal plates with tape and incubate at 37℃ in plate reader for 24h.
Our setting for LL-37 and Grammistin-Pp1:
Sample plate for GF-17 and Mixed anti-microbial peptides:
Biofilm staining
- Pipette LB out of the 96-well plate.
- Add 200ul ddH2O in each well.
- Pipette H2O out.
- Add 200μl ddH2O in each well.
- Pipette H2O out.
- Incubate for 15min in 37 ℃.
- Air dry (for around 15min).
- Add 200μl crystal violet (0.1%) in each well.
- Wash with ddH2O three times.
- Add 200μl 95% ethanol.
- Read ABS595.