In a 20 day incubation experiments very little of the starch had
been removed but starch removal increased in the 25-day and
30-day incubations. Yeast has two types of a-glucoamylases
(EC:3.2.1.3) (KEGG, 2013) but metabolism of starch only became
apparent after most of the other useable organic carbon sources
had begun to run out but yeast would not have been able to make
full use of starch because it lacks a full range of amylases such as
b-glucoamylases.