Fermentative biohydrogen production by a new chemoheterotrophic bacterium Citrobacter sp. Y19

• Published in: International journal of hydrogen energy 2003-12, Vol.28 (12), p.1353-1359
• Main Authors: Oh, You-Kwan, Seol, Eun-Hee, Kim, Jung Rae, Park, Sunghoon
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Citrobacter; Energy; Exact sciences and technology; Facultative anaerobe; Fermentation; Fuels; Glucose; Hydrogen; Sugars
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/S0360-3199(03)00024-7

A newly isolated Citrobacter sp. Y19 for CO-dependent H 2 production was studied for its capability of fermentative H 2 production in batch cultivation. When glucose was used as carbon source, the pH of the culture medium significantly decreased as fermentation proceeded and H 2 production was seriously inhibited. The use of fortified phosphate at 60– 180 mM alleviated this inhibition. By increasing culture temperatures (25–36°C), faster cell growth and higher initial H 2 production rates were observed but final H 2 production and yield were almost constant irrespective of temperature. Optimal specific H 2 production activity was observed at 36°C and pH 6–7. The increase of glucose concentration (1– 20 g/l ) in the culture medium resulted in higher H 2 production, but the yield of H 2 production (mol H 2/mol glucose) gradually decreased with increasing glucose concentration. Carbon mass balance showed that, in addition to cell mass, ethanol, acetate and CO 2 were the major fermentation products and comprised more than 70% of the carbon consumed. The maximal H 2 yield and H 2 production rate were estimated to be 2.49 mol H 2/ mol glucose and 32.3 mmol H 2/ g cell h , respectively. The overall performance of Y19 in fermentative H 2 production is quite similar to that of most H 2-producing bacteria previously studied, especially to that of Rhodopseudomonas palustris P4, and this indicates that the attempt to find an outstanding bacterial strain for fermentative H 2 production might be very difficult if not impossible.