Evidence is accumulating to challenge the paradigm that biogenic methanogenesis, considered a strictly anaerobic process, is exclusive to archaea. We demonstrate that cyanobacteria living in marine, freshwater, and terrestrial environments produce methane at substantial rates under light, dark, oxic, and anoxic conditions, linking methane production with light-driven primary productivity in a globally relevant and ancient group of photoautotrophs. Methane production, attributed to cyanobacteria using stable isotope labeling techniques, was enhanced during oxygenic photosynthesis. We suggest that the formation of methane by cyanobacteria contributes to methane accumulation in oxygen-saturated marine and limnic surface waters. In these environments, frequent cyanobacterial blooms are predicted to further increase because of global warming potentially having a direct positive feedback on climate change. We conclude that this newly identified source contributes to the current natural methane budget and most likely has been producing methane since cyanobacteria first evolved on Earth.

中文翻译：

---

水生和陆地蓝细菌产生甲烷。

越来越多的证据在挑战这种范式，即认为严格意义上的无氧过程的生物成甲烷作用是古细菌所独有的。我们证明了生活在海洋，淡水和陆地环境中的蓝细菌在光照，黑暗，有氧和缺氧条件下会大量产生甲烷，从而将甲烷生产与光驱动的初级生产力联系在一起，成为一组具有全球意义的古老光合生物。在氧气的光合作用过程中，甲烷的产生是由于使用稳定的同位素标记技术而产生的蓝细菌引起的。我们建议由蓝细菌形成甲烷有助于甲烷在氧气饱和的海洋和and石地表水中积聚。在这些环境中 由于全球变暖可能会对气候变化产生直接的积极反馈，因此，频繁出现的蓝藻水华预计会进一步增加。我们得出的结论是，这种新发现的来源为当前的自然甲烷预算做出了贡献，而且自从蓝细菌首次在地球上进化以来，很可能一直在生产甲烷。