I regularly make (grow) tempeh and koji and both require a food dehydrator to keep the temperature around 30°C for the duration of the fermentation (in my case,

I regularly make (grow) tempeh and koji and both require a food dehydrator to keep the temperature around 30°C for the duration of the fermentation (in my case, living in the Netherlands, so Western Europe). Both tempeh and koji are molds (mycelium that doesn't produce mushrooms). I also make milk kefir, water kefir, sourdough and kombucha and while none of these cultures require the higher temperatures, they do thrive in the higher temperatures. I also grow quite a few species of mushrooms and have learned that a lot of species incubate quite aggressively at higher temperatures (25-35°C).