Ni (II) and Mg (II) ions as factors enhancing biohydrogen production by Rhodobacter sphaeroides from mineral springs
메타 데이터
바이오화학분류
바이오정밀화학
연료
논문
Ni (II) and Mg (II) ions as factors enhancing biohydrogen production by Rhodobacter sphaeroides from mineral springs
학술지
International journal of hydrogen energy
저자명
Hakobyan, L.; Gabrielyan, L.; Trchounian, A.
초록
Various metal ions play a key role in biohydrogen (H<SUB>2</SUB>) 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<SUB>2</SUB> production by Rhodobacter sphaeroides strain MDC6521 isolated from mineral springs in Armenia were established. The highest growth specific rate was obtained with 4-6 μM Ni<SUP>2+</SUP> and 5 mM Mg<SUP>2+</SUP>. 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 Ni<SUP>2+</SUP> added but pH increased in different manner with Mg<SUP>2+</SUP>. In the presence of 2-4 μM Ni<SUP>2+</SUP> external oxidation-reduction potential (ORP) decreased to more negative values (-800 +/- 15 mV). This decrease of ORP indicated ~2.7-fold enhanced H<SUB>2</SUB> yield (9.80 mmol L<SUP>-1</SUP>) with Ni<SUP>2+</SUP> compared with the control (without Ni<SUP>2+</SUP>). The H<SUB>2</SUB> yield determined in the medium with Mg<SUP>2+</SUP> was ~2.2 fold higher than that with 1 mM Mg<SUP>2+</SUP>. These results reveal new regulatory ways to improve H<SUB>2</SUB> production by R. sphaeroides those were depending on Ni<SUP>2+</SUP> and Mg<SUP>2+</SUP> of different concentrations.