Hi Mais, 

You can do a serial dilution of your bacteria with fixed amount of fungi and test the minimum inhibitory concentration (MICs) by spreading it on growth media overnight and see if there is 0 growth that indicates your bacteria has fungicidal activity and if the growth seems to be affected and inhibited (fungistatic). There is also a rapid assay to test fungistatic activity. 

I suggest extracting a bacterial culture and testing the extract as opposed to co-culturing method mentioned above. This will allow you to eventually identify the compound of interest in a less complicated system after fractionation. Carrying out an anti-fungi assay over time, with multiple reads in a plate reader (ie 100 uL of fungi to .5, 1, and 2 uL of crude extract in DMSO in triplicate) may provide further insight into the nature of your compound. I commonly come across "active" wells in our assays that are clear in the morning (meaning no growth) and fully grown by 6 PM (this would be a fungistatic or a fungicide that is too low concentration or digested by the organism decreasing the effective concentration with time). Furthermore, if you re-plate fungi after treatment with the crude extract, and the fungi grow, then the compound is most likely a fungi-static. I hope this helps.

Thank you both, Mohammed and Carter.

Carter may I ask you if you know any paper that mentioned this assay?

Hi Mais,

Perhaps this article will be informative for you:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036021

It discusses a couple of different assays, including something similar to the Candida albicans assay that I was mentioning above as well as the commonly accepted disk-diffusion technique (on agar plates).

Are you extracting compounds from the organism in question? If so, you have many more options... Sometimes I encounter an anti-fungal "zone of inhibition" that only seems to manifest on solid state (agar) systems and I can not isolate the active compound from a crude mixture of ethyl acetate extracted fermentations. In these situations, I try to access this anti-fungal compound using different media types (fermentation) or increase the fermentation reaction to get a higher yield of extract (go from 100 mL to 10 L).

I tried to quickly find a publication outlining a procedure for re-testing surviving C. albicans or fungi, but came up empty-handed. This is a commonly used technique in T. vaginalis, and other anaerobic protozoa, to assess how effectively a compound kills a trophozoite (or cyst in the case of E. histolytica and G. lamblia). 

With that said, it may be beneficial to look at treated fungi under a microscope to see if the cells are actually dead or not. Perhaps a stain will help you qualify if a compound is rupturing the cells or preventing them from replicating.

Best of luck.