Utilization of hydrogen gas production for electricity generation in fuel cell by <i>Enterobacter aerogenes</i> ADH 43 with many kinds of carbon sources in batch stirred tank reactor

Abstract

Enterobacter aerogenes ADH-43 is a hydrogen gas (H₂) producing mutant bacterium and a facultative anaerobic microbe. This double mutant was obtained by classical mutagenetically treated in order to enhance H₂ production. In addition, this mutant has ability to degrade molasses from sugar factory as well as other carbon sources. The main goals of this research were to use E. aerogenes ADH-43 for fermentation in order to decide the best carbon sources and optimum concentration from molasses, glucose, cassava sugar, glycerol and biodiesel waste media in vial bottle. Moreover, to stabilize H₂ production, it was operated at 37°C and an initial pH 6.8. Performing the research in batch and fed-batch culture, utilizing it by converting to electricity using fuel cells in 50 ml vial bottle, 2% total sugar concentration of sugar cane molases was found to be the highest H₂ production (9.38 L H₂/L medium) during 24 h fermentation. It was also observed that in batch culture at 12 h fermentation, the volume, flow rate maximum, and the yield of H₂ production were 1.6 L H₂/L sugar molases, 73.4 ml H₂/min, and 2.99 mol H₂/mol sugar molases, respectively. Both sugar was consumed perfectly, colony count was 1.7 10⁷ cfu/ml, pH was nearly constant at 6.0, and finally the H₂ was drifted to fuel cell to generate electrical power until 4 V 0.25 A. Moreover, the volume, flow rate maximum, and the yield of H₂ production were 2.12 L H₂/L sugar molases, 107.7 ml H₂/min, and 3.84 mol H₂/mol sugar molases, respectively when the fed-batch culture was performed. This means nearly 1.3- fold yield of H₂ as compared to batch culture was obtained by adding 0.5 L of 2% sugar cane molasses at 5 and 12 h of fermentation in order to reach 7.0 V, 5.3 W and 0.38 A by a fuel cell.

Keywords: Enterobacter aerogenes ADH-43, H₂ production, molasses and fuel cell