As it have noted everywhere, there are control positive and negative strains for biofilm formation, however, when detecting the level of biofilm formation (strong, weak, ...) several different quantities have considered. Is there any specific formula for the levels determination based on OD values?
kind regards...
Put up 5 negative controls (only liquid media or saline without bacteria).
calculate mean OD of the neg. controls and add +2SD (Standard deviation of the values tpo it).
If any test biofilm well has OD above this value, it is taken positive.
thanks so much Dear Bhattacharyya
May I request a reference for this calculation method?
Dear Abdolmajid,
A better approach would be to use the negative control data (using sterile media) to compare with each of your tests using something like Dunnett's comparisons of means using a control. This will allow you to test the significance of the difference in OD600 (or whichever measurement you use - we use Crystal violet binding as measured by A575) directly, rather than accepting a common practice of plus or minus 2 SE,
Regards, Andrew
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