Effect of Fe (III) Ions on Hydrogenase Activity and Growth of the Cupriavidus necator H16 Strain in Diverse Growth Media

• Date: 2025
• Main Authors: Nikolyan, S.H., Margaryan, A.A., Poladyan, A.A., Ніколян, С.Г., Маргарян, А.А., Полядян, А.А.
• Format: Article
• Language: English
• Published: PH "Akademperiodyka" of the NAS of Ukraine 2025
• Online Access: https://ojs.microbiolj.org.ua/index.php/mj/article/view/327
• Journal Title: Microbiological Journal

Cupriavidus necator H16 possesses oxygen-tolerant [NiFe] hydrogenases, which can oxidize H2 in the presence of oxygen (O2), easily adapts between autotrophic and heterotrophic lifestyles, and has significant biotechnological potential. Aim. Тo investigate the growth characteristics of C. necator H16 using different nutrient media and heavy metal, particularly iron ions, for determination of optimal conditions maximizing Hyd activity. Methods. C. necator H16 was cultivated heterotrophically using Nutrient Broth (NB) and Fructose-Nitrogen (FN) minimal growth media, pH 7.0. The effects of iron (Fe(III)) ions on the activity of the bacterial H2-oxidizing Hyds (hydrogenases) and its growth properties were investigated. Bacterial growth was monitored by determining the optical density, OD570, under 570 nm. The total H2-oxidizing Hyd activity of whole cells of C. necator H16 was measured over a 72-hour growth period. Results. In the control samples without adding Fe ions, the activity was observed in the range of 0.5–0.2 U mg–1 cell dry weight (CDW) in both NB and FN media for up to 48 hours of bacterial growth. However, when 54 µM Fe ions were added to the media, the H2-oxidizing Hyd activity increased approximately 2–3 fold after 24 and 48 hours in both FN and NB media, compared to the control samples. Additionally, in the samples supplemented with Fe ions, a shift in the ORP from positive to negative values was observed, primarily starting from the exponential growth phase. After 24 hours, the NB medium showed stimulated biomass formation and Hyd activity compared to the FN medium. Conclusions. These findings suggest that certain conditions, such as the presence of higher amounts of iron ions and specific growth media, can enhance the Hyd activity during bacterial heterotrophic growth.