BGL-a with 19 copies δ-integrated bgl was gained and then seven ploidy series strains.
Mating type effect: specific activity of BGL-aα was lower than that of BGL-aa or -αα.
Maximum OD660 decreased with ploidy and specific activity increased with ploidy.
No typical mating type and ploidy effect on ethanol production in 10% cellobiose.
BGL-aα produced ethanol (titer 35.65 g/L and yield 83.69%) from pretreated corncob.