Production of hydrogen by a hydrogenase-deficient mutant of Rhodobacter capsulatus

• Published in: Journal of fermentation and bioengineering 1998-01, Vol.85 (5), p.470-475
• Main Authors: Ooshima, Hiroshi, Takakuwa, Susumu, Katsuda, Tomohisa, Okuda, Masaki, Shirasawa, Takeshi, Azuma, Masayuki, Kato, Jyoji
• Format: Article
• Language: English
• Subjects: BACTERIA; Biological and medical sciences; Biotechnology; ENZIMAS; ENZYME; ENZYMES; ethanolamine; Fundamental and applied biological sciences. Psychology; HIDROGENO; HYDROGEN; hydrogen production; hydrogenase deficient mutant; HYDROGENE; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; MUTANT; MUTANTES; MUTANTS; Rhodobacter capsulatus
• ISSN: 0922-338X
• DOI: 10.1016/S0922-338X(98)80064-0

The characteristics of Rhodobacter capsulatus ST410, a mutant of the wild strain B100 lacking hydrogenase activity, were investigated from the viewpoint of hydrogen production. When 30 mM dl-malate and 7 mM l-glutamate were used as carbon and nitrogen sources, respectively, in an argon atmosphere, a specific hydrogen evolution rate of 0.14 ml/h/mg-dry cells was obtained at 6600 lx and 33°C. The evolution rate strongly depended on the light intensity: the higher the light intensity, the larger the evolution rate became up to at least 6600 lx. R. capsulatus ST410 converted 60 mM malate to hydrogen at a yield of 68%, calculated as a percentage of the stoichiometric maximum for the complete conversion of the carbon source to H 2 and CO 2. On the other hand, when the wild strain was used under the same conditions, the yield was only 25%. R. capsulatus ST410 converted not only malate but also glucose and cellobiose to hydrogen with good yields (60% for 30 mM glucose and 66% for 7.5 mM cellobiose). Ethanolamine was found to be a good nitrogen source, which permitted a large amount of hydrogen to be evolved and also depressed the cell growth to low levels.