Ni (II) and Mg (II) ions as factors enhancing biohydrogen production by Rhodobacter sphaeroides from mineral springs

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• 作者：Lilit Hakobyan^a ; Lilit Gabrielyan^a ; Armen Trchounian^a ; ^b ; ^{Trchounian@ysu.am}
• 关键词：Ni (II) ; Mg (II) ; pH ; Oxidation-reduction potential ; Hydrogen photoproduction ; Rhodobacter sphaeroides
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：May, 2012
• 卷：37
• 期：9
• 页码：7482-7486
• 文件大小：359 K

摘要

Various metal ions play a key role in biohydrogen (H₂) production by phototrophic bacteria through incorporation into or stimulating the responsible enzymes and/or related pathways. The Ni (II) and Mg (II) ions effects on growth and H₂ production by Rhodobacter sphaeroides strain MDC6521 isolated from mineral springs in Armenia were established. The highest growth specific rate was obtained with 4-6聽渭M Ni²⁺ and 5聽mM Mg²⁺. pH of the growth medium changed from 7.0 to 9.2-9.4 during the bacterial growth up to 72聽h in spite of Ni²⁺ added but pH increased in different manner with Mg²⁺. In the presence of 2-4聽渭M Ni²⁺ external oxidation-reduction potential (ORP) decreased to more negative values (鈭?00聽卤聽15聽mV). This decrease of ORP indicated 鈭?.7-fold enhanced H₂ yield (9.80聽mmol聽L^鈭?) with Ni²⁺ compared with the control (without Ni²⁺). The H₂ yield determined in the medium with Mg²⁺ was 鈭?.2 fold higher than that with 1聽mM Mg²⁺. These results reveal new regulatory ways to improve H₂ production by R. sphaeroides those were depending on Ni²⁺ and Mg²⁺ of different concentrations.