Re-routing photosynthetic energy for continuous hydrogen production in vivo

Abstract

BackgroundHydrogen is considered a promising energy vector that can be produced from sustainable resources such as sunlight and water. In green algae, such as Chlamydomonas reinhardtii, photoproduction of hydrogen is catalyzed by the enzyme [FeFe]-hydrogenase (HydA). Although highly efficient, this process is transitory and thought to serve as a release valve for excess reducing power. Up to date, prolonged production of hydrogen was achieved by the deprivation of either nutrients or light, thus, hindering the full potential of photosynthetic hydrogen production. Previously we showed that the enzyme superoxide dismutase (SOD) can enhance HydA activity in vitro, specifically when tied together to a fusion protein.ResultsIn this work, we explored the in vivo hydrogen production phenotype of HydA–SOD fusion. We found a sustained hydrogen production, which is dependent on linear electron flow, although other pathways feed it as well. In addition, other characteristics such as slower growth and oxygen production were also observed in Hyd–SOD-expressing algae.ConclusionsThe Hyd–SOD fusion manages to outcompete the Calvin–Benson cycle, allowing sustained hydrogen production for up to 14 days in non-limiting conditions.

Membrane Inlet Mass Spectrometry: A Powerful Tool for Algal Research

“…H 2 photoproduction by microorganisms has recently regained huge interest for biofuel production due to recent improvements in strains and experimental protocols ( Tóth and Yacoby, 2019 ). The use of MIMS should help in evaluating the upcoming combination of newly developed H 2 production protocols ( Kosourov et al., 2018 ; Nagy et al., 2018 ) and previously characterized mutants photo-producing more H 2 ( Tolleter et al., 2011 ; Eilenberg et al., 2016 ; Burlacot et al., 2018 ; Ben-Zvi et al., 2019 ). This has recently started using flv mutants ( Jokel et al., 2019 ) and is promising for future bio H 2 production developments.…”

Hyaluronic Acid Allows Enzyme Immobilization for Applications in Biomedicine

“…Production of hydrogen ( ) for a comparatively clean and renewable option was also attempted through the usage of enzyme-facilitated metabolism algal functions [ 3 , 29 ]. Among current methods for production are pyrolysis [ 30 , 31 , 32 ] and gasification [ 33 , 34 ] of carbon-based fossil fuels, sewage sludge, biomass as well as steam reforming of natural gas [ 35 , 36 ], and electrolysis of water [ 34 , 37 , 38 ], respectively.…”

“…To mitigate such limitations, enzyme immobilization has become a prevalent approach. This review provides an overview of current implementation of enzymes in synthetic applications with focus on biofuel [ 1 , 2 , 3 ], textile [ 4 , 5 , 6 , 7 , 8 ], detergent [ 4 ], waste management [ 8 , 9 ], and food and drink industries [ 10 , 11 ] respectively. Subsequently, particular attention is directed towards enzyme immobilization using hyaluronic acid (HA) scaffolds, a polysaccharide consisting of alternating β-1,4-D-glucuronic acid and β-1,3-N-acetyl-D-glucosamine rings known for its high biocompatibility, biodegradability, viscoelasticity, and hydrophilicity [ 12 , 13 , 14 ], to thus help emphasize enzymes’ implementation in biomedical applications.…”

Biohydrogen production from microalgae—Major bottlenecks and future research perspectives

“…[46] Expression of a hydrogenasesuperoxide dismutase fusion protein resulted in an expression of 20 ml H 2 /d/L culture for 14 days. [47] A C3 mutant of C. reinhardtii with an imbalance in the ratio of PSI/PSII (0.85 for the wild type and 0.33 for the C3 mutant) resulted in an over-reduction of the plastoquinone pool and sustained hydrogen production at the rate of 3 ml H 2 /d/L for 42 days. [48] Other studies inhibit carbon fixation by deftly manipulating culture conditions such as limited carbon substrate supply in the form of CO 2 [49] or pulsing light in prolonged dark incubation periods.…”