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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 18, No. 3, 2015, pp. 221-230
Bioline Code: ej15037
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 18, No. 3, 2015, pp. 221-230

 en Photo-fermentational hydrogen production of Rhodobacter check for this species in other resources sp. KKU-PS1 isolated from an UASB reactor
Assawamongkholsiri, Thitirut & Reungsang, Alissara

Abstract

Background: In this study, the detection of nifH and nifD by a polymerase chain reaction assaywas used to screen the potential photosynthetic bacteria capable of producing hydrogen from five different environmental sources. Efficiency of photo-hydrogen production is highly dependent on the culture conditions. Initial pH, temperature and illumination intensity were optimized for maximal hydrogen production using response surface methodology with central composite design.
Results: Rhodobacter check for this species in other resources sp. KKU-PS1 (GenBank Accession No. KC478552) was isolated from the methane fermentation broth of an UASB reactor. Malic acid was the favored carbon source while Na-glutamate was the best nitrogen source. The optimum conditions for simultaneously maximizing the cumulative hydrogen production (Hmax) and hydrogen production rate (Rm) from malic acid were an initial of pH 7.0, a temperature of 25.6°C, and an illumination intensity of 2500 lx. Hmax and Rm levels of 1264 ml H2/l and 6.8 ml H2/L-h were obtained, respectively. The optimum initial pH and temperature were further used to optimize the illumination intensity for hydrogen production. An illumination intensity of 7500 lx gave the highest values of Hmax (1339 ml H2/l) and Rm (12.0 ml H2/L-h) with a hydrogen yield and substrate conversion efficiency of 3.88 mol H2/molmalate and 64.7%, respectively.
Conclusions: KKU-PS1 can produce hydrogen from at least 8 types of organic acids. By optimizing pH and temperature, a maximal hydrogen production by this strain was obtained. Additionally, by optimizing the light intensity, Rm was increased by approximately two fold and the lag phase of hydrogen productionwas shortened.

Keywords
nifD; nifH; Photo fermentation; Purple-non-sulfur bacteria

 
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