Optimal oxygen addition was 0.28 mL/(g TS·day) for corn straw.
Oxidation reduction potential of micro-aerobic fermentation was −300 ∼ −150 mV.
Micro-aerobic hydrogen production was butyric acid-type fermentation.
The micro-aerobic condition had strong buffer ability.
Citrobacter sp. and Escherichia sp. were unique to micro-aerobic system.