My new word for the day and first post.
I've got a notebook that I keep notebook pages of kanji in and attempt to add to with compounds when I find them today I'm working on haha 母 and found a new word to go with it was:
yeast 酵母/こうぼ/koubo (lit. ferment mother)
the first character is fermentation
when used in yahoo honyaku it doesn't translate alone so I'm going to assume this is the more popular usage unless you use イースト which seems not right more used for east
I even found a cute website with a mother demonstrating yeast to her daughter in a glass.