I recently attempted to Create growth curves for Candida Albicans and Penicillium rubens and have failed miserably, I'd like to share with you my protocol to see maybe I'm missing something:
- I grew starter cultures in YM broth over a few nights(yeast culture was 2-3 days old, mold culture was 5-6 days old). I grew both cultures in a semi sealed sterile erlemmayer at room temperature placed on a rotating orbital shaker(spins in a cyrcle) at about 65 rpms. - I saw massive growth in both starter cultures.
- I considered the grown starter cultures as 7 log (10,000,000 CFU/ml) concentration and I diluted both starters x4 and x5 and infected new samples (clean ym broth in erlenmeyer) at what I learned is considered 3 log and 2 log growth concentration.
- I placed the 4 samples(2 for each fungi, at 2 different infection levels) on the same rotating shaker and started mesuring time - sampeling each bottle into 2 agar plates (my agar is oxytetracycline - glucose yeast extract agar) at 2 different dilutions (2 log and 3 log).
- I sampeled the yeast samples every 3.5 hours, and diluted it another +1 ratio(1:10) each time considereing 3.5 hours is the average growth time for yeasts, for 7 times total.I sampeled the mold samples every 6 hours, and diluted it another +1 ratio(1:10) each time considereing 6 hours is the average growth time for molds , for 10 times total.
- All plates were left for incubation in room temerature for 3 days (yeasts) and 5 days(molds).
Non of my mold plates showed any growth at all, and my yeast plates showed very random growth, showing some growth over the first few time points, then dropping to very low growth(with some plates showing 0 colonies) before going back to show some growth toward the end of the time points.
Please, if anyone has experience with growth curves or with growing these organisms, I'd appriciate any assistance you can offer.