my bacterial culture- E. aerogenes & Klebsiella are giving methyl red test positive, what can be the reason?
Also giving difficulty in interpretation of results of VP test. Never faced such problem previously.
IF PURE CULTURES THEN SHOULDNOT BE PROBLEM SO NEED TO CHECK FOR PURITY
You have used ATCC cutures & checked the purity so no question of contamination . I can suggest that the cultures used for MR testing shoul be minimum 48 h grown as early stage culture may result false-positive MR.
Now a days even the ATCC also reported contaminant so check the purity of the culture by 16S rRNA . Following is one of case study for contamination in ATCC culture.
Article A Laboratory Case Study of Efficient Polyhydoxyalkonates Pro...
The methyl red test must not be performed unless the medium has been incubated for a minimum of 48 hours. Tests that are run too early may result in false-positive interpretation. It is important that a light inoculum be used. If an inoculum is too heavy, bacterial growth may be inhibited and result in invalid test results. False-positive VP results may occur if VP tests are read beyond one hour following the addition of reagents.
Thank you all for your response. It did help me cross check and get the appropriate results.
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