Microbial hydrogen production from sweet potato starch residue

Clostridium Butyricum could produce hydrogen from a sweet potato starch res idue upon supplementation of nitrogen sources. A repeated batch culture usi ng a mixed culture of C. butyricum and Enterobacter aerogenes produced hydr ogen with a yield of 2.4 mol H-2/mol glucose under a controlled culture pH of 5.25 in a medium consisting of the sweet potato starch residue and 0.1% Polypepton without addition of any reducing agents. Rhodobacter sp. M-19 pr oduced hydrogen from the supernatant of the culture broth obtained in the r epeated batch culture containing C. butyricum and E. aerogenes when 50 mug/ l Na2MoO4. 2H(2)O and 20 mg/l EDTA were added to the supernatant and it was cultured under a controlled culture pH of 7.5. A high yield of hydrogen of 7.0 mol H-2/mol glucose from the starch remaining in the starch residue wa s attained in two-step repeated batch cultures containing C. butyricum and E. aerogenes, and by Rhodobacter sp. M-19.