Is it necessary to lower the pH of Mueller-Hinton agar supplemented with 2% glucose in order to prevent bacterial contamination?
Can we add conc HCL to lower the pH?
Many fungi grow better at acidic pH, whereas few bacteria (known as acidophiles) grow at acidic pH. That is why the pH of some media for culturing fungi such as SDA is acidic. However, such media also contains constituents that inhibit bacterial growth.
To use Mueller-Hinton agar supplemented with 2% glucose for anti-fungal susceptibility testing you will need to add a broad spectrum antibiotic such as streptomycin (100 ug/ml). Lowering the pH may not be important, since fungi can also grow at neutral pH.
Lowering the pH will not prevent bacterial contamination - the pH here should be 7.2-7.4 Article Susceptibility test for fungi: Clinical and laboratorial cor...
If you're having trouble with bacterial contamination - make sure your fungal cultures are pure and check your aseptic technique.
Many fungi grow better at acidic pH, whereas few bacteria (known as acidophiles) grow at acidic pH. That is why the pH of some media for culturing fungi such as SDA is acidic. However, such media also contains constituents that inhibit bacterial growth.
To use Mueller-Hinton agar supplemented with 2% glucose for anti-fungal susceptibility testing you will need to add a broad spectrum antibiotic such as streptomycin (100 ug/ml). Lowering the pH may not be important, since fungi can also grow at neutral pH.
If no measure is taken to inhibit bacterial growth, then it is of no advantage.
... discover the procedure that will be best suited for your purpose.
... Ciprofloxacin will do just fine... then again you have to take into cognizance the effect of lowering pH on the antibacterial activity of ciprofloxacin (or any other antibiotics for that matter)
Article Susceptibility test for fungi: Clinical and laboratorial cor...
Generally for the growth of bacteria neutral pH(&-7.5) is favorable.
For the fungi slightly acidic pH (5-6) is preferable, or it is reduced itself during the growth of fungi.
The adjustment of pH can be done by H Cl/ NaOH during the media preparation.
This pH adjustment is done as it is optimal for the growth of the organism.
It can also minimize the growth of bacteria to some extent, you can make use of antibacterial antibiotics for the inhibition of antibacterial growth. Similarly anti fugal antibiotics for the inhibition of fungal growth as per the requirement.
pH within the range of Sabouraud agar will do little to discourage bacterial growth. Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis grow well enough on Sabouraud agar. More importantly - there should be no reason why you need to inhibit bacterial contamination - if you're working with a pure culture of the fungal isolate and have reasonable aseptic technique and equipment. The objective mentioned was susceptibility testing and departure from established media criteria (here pH) may generate results inconsistent with expectations.
be aware that altering the the pH or including antibiotics in the agar can interfere with the antibiotics you want to test. I suggest you sub culture your fungi until it is contaminant free then perform the sucseptibility testing according to standardized methods. Candida and Aspergillus is normal human pathogens and Eucast methods work well - use MIC strips (E-test). See Assel Saeeds answer above.
Good luck!
Lowering pH enhance growth of lactic acid bacteria and many bacterial pathogens can grow at decreased pH values ,You can work at asceptic conditions and you will success
Müller-Hinton Agar (modified to determine susceptibility to antimycotics, according to the CLSI standard) is recommended for studying the sensitivity of yeasts and fungi to antimicotics by the disk diffusion method.
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