Yoshida Akihito, Nishimura Taku, Kawaguchi Hideo, Inui Masayuki, Yukawa Hideaki
Microbiology Research Group, Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Soraku-Gun, Kyoto, Japan.
Appl Microbiol Biotechnol. 2007 Mar;74(4):754-60. doi: 10.1007/s00253-006-0721-y. Epub 2006 Nov 17.
A three-step biohydrogen production process characterized by efficient anaerobic induction of the formate hydrogen lyase (FHL) of aerobically grown Escherichia coli was established. Using E. coli strain SR13 (fhlA (++), DeltahycA) at a cell density of 8.2 g/l medium in this process, a specific hydrogen productivity (28.0 +/- 5.0 mmol h(-1) g(-1) dry cell) of one order of magnitude lower than we previously reported was realized after 8 h of anaerobic incubation. The reduced productivity was attributed partly to the inhibitory effects of accumulated metabolites on FHL induction. To avoid this inhibition, strain SR14 (SR13 DeltaldhA DeltafrdBC) was constructed and used to the effect that specific hydrogen productivity increased 1.3-fold to 37.4 +/- 6.9 mmol h(-1) g(-1). Furthermore, a maximum hydrogen production rate of 144.2 mmol h(-1) g(-1) was realized when a metabolite excretion system that achieved a dilution rate of 2.0 h(-1) was implemented. These results demonstrate that by avoiding anaerobic cultivation altogether, more economical harvesting of hydrogen-producing cells for use in our biohydrogen process was made possible.
建立了一种三步生物制氢工艺，其特点是能有效地厌氧诱导需氧生长的大肠杆菌甲酸氢裂解酶（FHL）。在此工艺中，使用细胞密度为8.2 g/l培养基的大肠杆菌SR13菌株（fhlA（++），DeltahycA），厌氧培养8小时后，实现的比产氢率（28.0±5.0 mmol h⁻¹ g⁻¹干细胞）比我们之前报道的低一个数量级。产氢率降低部分归因于积累的代谢产物对FHL诱导的抑制作用。为避免这种抑制，构建了SR14菌株（SR13 DeltaldhA DeltafrdBC）并使用，结果比产氢率提高了1.3倍，达到37.4±6.9 mmol h⁻¹ g⁻¹。此外，当实施达到2.0 h⁻¹稀释率的代谢产物排泄系统时，实现了144.2 mmol h⁻¹ g⁻¹的最大产氢率。这些结果表明，通过完全避免厌氧培养，使得在我们的生物制氢工艺中更经济地收获产氢细胞成为可能。
