ohh gee two of my favorite subjects, i have been experimenting making exotic ferments for quite sometime now water kefir being my solid favorite for most things, i will say the tannins are very harsh for many micro organisms, and i would tread very lightly there, also most of the lacto family are facultative as aposed to obligate which means they survive aerobicly and anearobicly so you dont need to make disgusting anearobic compounds...also i would tend to go alcohol yeast or live vineagar...these would be the most hearty organisms you would also get the strongest pull with a solution high in alcohol or natural acids, though the alcohol would be more of a tincture while the acids in vineagar would act more like you are fantasising doing all sorts of bonding and restructuring and such, the reference to sweet ayahuaska is unfermented or unly lightly fermented, if they let it ferment for any significant time it gets sour because they eat all the sugars, (caapi tends to be fairly high in sugers in some cases) i would avoid using vegetables as food sources in a sensitive ferment your just inviting wierdness...i have succesfully made kefir and mead with psliocin/psilocybin, we found (anocdotaly) that it increases innitial potency, and then after about a week starts to mellow and the experience changes pretty significantly, we also were experimenting with tartaric acid as a way to preserves the active molecules...i have also experimented with fermenting a variety of other neuro transmitters...definitly want to try getting your culture used to it before you start puting large amounts in, it might be worth concentrating you plant matter before fermenting...maybe do a resin tek, then you would also have the opportunity to pul alot of those tannins out with the egg white/geletin tek...