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

作者：Hakobyan Lilit; Gabrielyan Lilit; Trchounian Armen^*

来源：International Journal of Hydrogen Energy, 2012, 37(9): 7482-7486.

DOI：10.1016/j.ijhydene.2012.01.144

• Ni (II)
• Mg (II)
• pH
• Oxidation-reduction potential
• Hydrogen photoproduction
• Rhodobacter sphaeroides

Various metal ions play a key role in biohydrogen (H-2) 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 H-2 production by Rhodobacter sphaeroides strain MDC6521 isolated from mineral springs in Armenia were established. The highest growth specific rate was obtained with 4-6 mu M Ni2+ and 5 mM Mg2+. pH of the growth medium changed from 7.0 to 9.2-9.4 during the bacterial growth up to 72 h in spite of Ni2+ added but pH increased in different manner with Mg2+. In the presence of 2-4 mu M Ni2+ external oxidation-reduction potential (ORP) decreased to more negative values (-800 +/- 15 mV). This decrease of ORP indicated similar to 2.7-fold enhanced H-2 yield (9.80 mmol L-1) with Ni2+ compared with the control (without Ni2+). The H-2 yield determined in the medium with Mg2+ was similar to 2.2 fold higher than that with 1 mM Mg2+. These results reveal new regulatory ways to improve H-2 production by R. sphaeroides those were depending on Ni2+ and Mg2+ of different concentrations.

• 出版日期2012-5