My feeling is you're virtually always going to have more bacteria than fungi in a compost tea. Most bacteria seem to like, or at least not mind floating about in solution. Most fungi seem to prefer being anchored to something. Fungi have hyphae and can physically penetrate solid objects with it (sexy, I know). They secrete (ohh yeah) enzymes which help them do a lot of their digesting outside of the cell (extracellularly), which I imagine could be difficult in a solution where stuff keeps floating by and away.
Fungi will grow in teas, though, under the right conditions. The more fungal filaments you have to begin with, the greater the likelihood you'll succeed at getting something dominated by fungi. The typical procedure is to "jump start" the fungi in the compost\humus you're using. You do this by taking a cup full of compost and mixing in a foodstock with the tougher to digest components like cellulose and lignin. Something like oatmeal, flax seed meal, brown rice flour, etc. kelp meal should work, too. If you use oatmeal or a bulkier material, grind it up first to near powder consistency.
Moisten after mixing, but try not to get it too wet, then put it somewhere warm and dark. You may want to cover it partially as you also don't want it to dry out. After 3-5 days or more you'll have a fuzzy white (and maybe green, or yellowish) mass of mycelium. Break this up into nugget, nickle-quarter sized pieces and brew with
Quality compost\castings should not really have pathogens in the first place. Any opportunists are actually suppressed by the activity of beneficial or neutral microbes in the material. The best of the beneficial microbes live in harmony or symbiosis with the plant roots in the rhizosphere. Plant roots exude compounds to feed these microbes and actually influence what kinds of microbial communities are growing there.
Microbes live on plant leaves, as well. When you foliar/spray finished AACT, you cover the leaves in a layer of microbes which will continue to exert their beneficial effects. At the very least, a microbe can be "good" simply by not being "bad": taking up space and resources, and out-competing the microbes which could really do the plant harm.
