Extremely Low D/H Ratios of Photoproduced Hydrogen by Cyanobacteria

Yao-Hua Luo, Leonel Steinberg, Shoichiro Suda, Shuzo Kumazawa, Akira MitsuiPlant and Cell Physiology, Volume 32, Issue 6, September 1991, Pages 897–900,

Abstract

Cyanobacteria, having primary photosynthetic reactions similar to higher plants, are capable of producing large quantities of molecular hydrogen by nitrogenase and/or hydrogenase delivering electrons to hydrogen ions via ferredoxin or oxidation of NADPH. We measured the deuterium/hydrogen (D/H) ratios of the hydrogen gas photoproduced by Synechococcus sp. Miami BG 043511 and Anabaena sp. TU 37-1, and demonstrate that ΔD values of their hydrogen gas are extremely low (about − 600%) when compared with that of available water (−7%).This depletion gives a mean fractionation factor (a) of 0.43, which is similar to that calculated for hydrogen ions at equilibrium with water (0.35) and hydrogen produced by electrolysis of water (0.24) but significantly different from those of carbon bound hydrogens (>0.83). Thus hydrogen ions available for protonation of NADP+ may be extremely deuterium depleted. Our results may explain why D/H ratios of nitrated cellulose or lipids from most plants are always depleted relative to water available for photosynthesis.

REVIEW

Photobioreactor cultivation strategies for microalgae and cyanobacteria

Tylor J. Johnson Sarmila Katuwal Gary A. Anderson Liping Gu Ruanbao Zhou William R. GibbonsFirst published: 08 March 2018 https://doi.org/10.1002/btpr.2628

Abstract

The current burden on fossil‐derived chemicals and fuels combined with the rapidly increasing global population has led to a crucial need to develop renewable and sustainable sources of chemicals and biofuels. Photoautotrophic microorganisms, including cyanobacteria and microalgae, have garnered a great deal of attention for their capability to produce these chemicals from carbon dioxide, mineralized water, and solar energy. While there have been substantial amounts of research directed at scaling‐up production from these microorganisms, several factors have proven difficult to overcome, including high costs associated with cultivation, photobioreactor construction, and artificial lighting. Decreasing these costs will substantially increase the economic feasibility of these production processes. Thus, the purpose of this review is to describe various photobioreactor designs, and then provide an overview on lighting systems, mixing, gas transfer, and the hydrodynamics of bubbles. These factors must be considered when the goal of a production process is economic feasibility. Targets for improving microalgae and cyanobacteria cultivation media, including water reduction strategies will also be described. As fossil fuel reserves continue to be depleted and the world population continues to increase, it is imperative that renewable chemical and biofuel production processes be developed toward becoming economically feasible. Thus, it is essential that future research is directed toward improving these processes. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:811–827, 2018