The ability of some photosynthetic microorganisms, particularly cyanobacteria and microalgae, to produce hydrogen (H2) is a promising alternative for renewable, clean-energy production. However, the most recent, related studies point out that much improvement is needed for sustainable cyanobacterial-based H2 production to become economically viable. In this study, we investigated the impact of induced O2-consumption on H2 photoproduction yields in the heterocyte-forming, N2-fixing cyanobacterium Nostoc PCC7120. The flv3B gene, encoding a flavodiiron protein naturally expressed in Nostoc heterocytes, was overexpressed. Under aerobic and phototrophic growth conditions, the recombinant strain displayed a significantly higher H2 production than the wild type. Nitrogenase activity assays indicated that flv3B overexpression did not enhance the nitrogen fixation rates. Interestingly, the transcription of the hox genes, encoding the NiFe Hox hydrogenase, was significantly elevated, as shown by the quantitative RT-PCR analyses. We conclude that the overproduced Flv3B protein might have enhanced O2-consumption, thus creating conditions inducing hox genes and facilitating H2 production. The present study clearly demonstrates the potential to use metabolic engineered cyanobacteria for photosynthesis driven H2 production.

中文翻译：

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Flv3B黄素二铁的过量生产会通过固氮蓝细菌Nostoc PCC 7120增强光生物产氢。

一些光合微生物，特别是蓝细菌和微藻产生氢气（H2）的能力是可再生清洁能源生产的有前途的替代方法。但是，最新的相关研究指出，要使基于蓝藻的可持续H2生产在经济上可行，还需要进行大量改进。在这项研究中，我们调查了诱导的O2消耗对形成H2的固定N2的蓝细菌Nostoc PCC7120中H2光产生的影响。flv3B基因编码Nostoc异种细胞中天然表达的flavodiiron蛋白质，过表达。在有氧和光养生长条件下，重组菌株显示出比野生型显着更高的H 2产生量。固氮酶活性测定表明flv3B过表达不会提高固氮率。有趣的是，如定量RT-PCR分析所示，编码NiFe Hox氢化酶的hox基因的转录显着提高。我们得出结论，过量生产的Flv3B蛋白可能增强了O2的消耗，从而创造了诱导hox基因和促进H2产生的条件。本研究清楚地证明了利用代谢工程蓝细菌进行光合作用驱动的H2产生的潜力。因此创造了诱导hox基因并促进H2产生的条件。本研究清楚地证明了利用代谢工程蓝细菌进行光合作用驱动的H2产生的潜力。因此创造了诱导hox基因并促进H2产生的条件。本研究清楚地证明了利用代谢工程蓝细菌进行光合作用驱动的H2产生的潜力。