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The effect of dithiothreitol (DTT) on enhancing ethanol production from syngas using Clostridium strain P11 (ATCC PTA-7826) was investigated in 250 mL serum bottles. Reducing agents help in regeneration of NADH from NAD+. NADH is utilized in the production of alcohol from aldehydes. The effect of DTT was studied in two different media: 0.1% (w/v) yeast extract, and 1% (w/v) corn steep liquor. Strain P11 was fed with syngas every 24 h, and samples were collected to measure pH, cell mass, and product concentrations. Various concentrations of DTT were examined. Results showed more than a 350% increase in ethanol concentration in media that contained at least 7.5 g L-1 of DTT after 360 h of fermentation compared to the control medium (without DTT) in 0.1% (w/v) yeast extract medium. However, only a 35% increase in ethanol production was noticed in 1% (w/v) corn steep liquor in the presence of 2.5 and 5.0 g L-1 of DTT compared to the control medium. The results suggested that the use of small concentrations of DTT in the broth enhances ethanol production from syngas. Improvement in ethanol production efficiency will increase the cost-effectiveness of the syngas fermentation technology.