緑藻クラミドモナスにおける窒素欠乏による光合成的水素産生の誘導
The unicellular green alga Chlamydomonas reinhardtii produces molecular hydrogen via the [FeFe]-hydrogenase HYD1, which accepts electrons from ferredoxin PetF under photosynthetic conditions. This study examined hydrogen evolution triggered by nitrogen starvation, a condition known to promote starch and lipid accumulation. Nitrogen-deprived cells maintained higher photosystem II photochemical activity initially, causing approximately a 2-day delay in hydrogen production onset relative to sulfur-deprived cultures. Despite substantial starch accumulation, both hydrogen yields and the degree of starch degradation were markedly lower under nitrogen deficiency than under sulfur deficiency. Starch breakdown rates in darkness were comparable between the two nutritional conditions. Methyl viologen treatment enhanced photosystem II efficiency in sulfur-depleted cells but showed minimal effect under nitrogen starvation. Degradation of the cytochrome b6f complex and reduced ferredoxin levels under nitrogen starvation are proposed as factors limiting the conversion of carbohydrate reserves into hydrogen gas.
Nitrogen starvation leads to degradation of the cytochrome b6f complex and reduced ferredoxin levels, creating a bottleneck in photosynthetic electron flow to HYD1-mediated hydrogen production.
This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/22020754