In this study ethanol stimulates the growth rate of cyanobacteria and acetate has no effect on cyano growth rate.
Characterization of an Alcohol Dehydrogenase from the Cyanobacterium Synechocystis sp. Strain PCC 6803 That Responds to Environmental Stress Conditions via the Hik34-Rre1 Two-Component System▿†
http://jb.asm.org/content/191/13/4383.full
From it:
"As shown in Table 2, the enzyme was active toward a wide variety of primary alcohols and their corresponding aldehydes, but neither ketones nor secondary alcohols were effective substrates."
Table 2:
http://jb.asm.org/content/191/13/4383/T2.expansion.html