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N0obL3T 05-03-2012 07:51 PM

Need help with a quantitative assay
I have recently started working in a chemical engineering lab as a summer student and am now required to devise a bacterial assay to assess the antibacterial properties of a photocatalyst on activated carbon.

The problem I am faced with is trying to determine the best course of action to obtain quantitative data on the antibacterial effects of this catalyst against E.coli.

The main issues that arise consist of the difficulty of using OD measurement methods due to the nature of the catalyst (activated carbon/black powder) and the difficulty of separating the catalyst from the bacterial culture to use standard plate count methods (particles interacting with damaged cells, gel inconsistencies). This is the first time I would be devising a full protocol by myself, so I wouldn't mind getting all the help I can get. I guess my question comes down to if anyone has advice on methods they know of that could help me in my situation.


p.s. for preliminary zone of inhibition testing, I was considering incubating agar plates right-side up (as opposeed to the usual upside down), because the catalyst discs to be used will not adhere well to the agar gel. Is there anyway to minimize the condensation from the plates to avoid this issue?

Jorge1907 05-06-2012 10:02 AM

Re: Need help with a quantitative assay
Wonder how a photocatalyst will be effectively activated if assocated with an opaque carrier like carbon black - but engineers playing at microbiology never fail to surprise.

If your putative antimicrobial material is insoluble, zone of inhibition testing will not be useful. You could attempt an MPN-type of approach - combine bacterial suspension with material (photoactivated before or consistent with exposure of culture), incubate, dilute a sample through a series of ten-fold dilutions towrd extinction in broth - incubate, noting the dilution that showed growth either visually (might try adding TTC and look for color change), by streak to an agar medium, etc. Would be helpful to use a medium that neutralizes the putative antimicrobial activity but you're not assured at this point that there is any so I'd just go with above for now.

Is this Titanium oxide?

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