fungal nutrient broth?

Okay, to satisfy my own need for scientific investigation, no matter how amateur, I've begun inspecting any types of growth or organisms growing on foods accidentally left out (or stuff in unknown places by my children to be discovered later or left in the fridge to long). One of the interesting things is that plates with oil on them (we use olive oil and flaxseed oil) left out for the same amount of times having been used for similiar dishes tend to NOT visibly grow things (from mold to creepy crawlies) or develop nasty odors. However when I mixed straight vitamin C with flaxseed oil and water and accidentally left it in the spare room in a fit of absentmindedness it DID grow a particularly beautiful green white mold. It grew on the surface and not into the oil between the surface and the water. It seemed very healthy looking. I wanted to save some for microscope inspection but had no suitible safe place to keep it until I could do so. Sad:(. But it leads me to suspect (using experiential learning, not what I can go look up in a text book) that oil is a useful inhibitor of maggots, fruit flies, mold, and though I could not directly observe it without microscopic aid, I suspect bacteria. However, when the appropriate nutrients in the appropriate forms (such as dissolvable powder) are mixed, oil may be a suitable media or surface to grow specific fungi (and/or bacteria). Olives with garlic stored in vinegar(with possilbe sulfites) salt, water and lactic acid attract fruit flies. I was always under the impression that vineger (acetic acid) isa preservative. Perhaps its not a preservative in the case of fruit flies, but preserves against bacteria and mold (I believe garlic has been shown to be anti-fungal and anti-bacterial) or perhaps another ingredient negates certain preservative properties such as the lactic acid. Without proof, who knows. I suspect it doesn't significanty repel fruit flies, the preservative properties of the ingredients are limited to bacteria and mold.