Ethanol production is simple fermentation of sugar by yeast. It is possible to ferment complex starches by use of a mold called Aspergillus oryzae. The mold converts complex starches into simple sugars that the yeast can convert to ethyl(or ethanol), wich is drinkable alcohol.
The japanese invented this process to make rice wine...aka sake...pronounced “socky’.
But the fibrous matter, or cellulose, can only be converted to wood alcohol(methanol). As far as I know, that is. In the old days of bootlegging moonshine, a bad batch that killed people was simply a batch of grain alcohol(ethanol) that had been contaminated with a bit of wood alcohol. Bacteria produces wood alcohol. Yeast produces grain alcohol.
Then there is potato oil, or fusel oil. This is a nasty byproduct of normal fermentation that gives you a headache with your hangover.
Thanks for the info.