Hydrogen export from intertidal cyanobacterial mats: sources, fluxes, and the influence of community composition

We examined H2 accumulation and export in 3 types of greenhouse-reared mats kept under natural light-dark conditions and controlled wetting and drying cycles that simulate low-, mid- and high-tidal height periodicity. All mats released H2 reproducibly and sustainably for longer than 1.5 years of incubation. Net H2 export took place in a pulsed daily manner, starting soon after dusk, and waning in the early morning hours, as photosynthesis resumed. Community composition by pyrosequencing of 16S rRNA and hoxH genes, indicate that filamentous non-heterocystous cyanobacteria (e.g., Lyngbya, Microcoleus) were important in the process of H2 export, as was the relatively low abundance of methanogens and sulfate reducers.

我们研究了三类在自然光暗条件下培育、并通过可控干湿循环模拟低潮、中潮及高潮潮汐周期的温室培育微生物垫中的氢气（H₂）积累与输出过程。所有受试微生物垫均可稳定且可重复地释放氢气，该释放过程在超过1.5年的孵育周期内持续有效。氢气净输出呈现每日脉冲式节律：于黄昏后不久启动，并在清晨光合作用恢复时逐渐减弱。通过焦磷酸测序（pyrosequencing）分析16S核糖体RNA（16S rRNA）与hoxH基因的群落组成结果显示：丝状无异形胞蓝细菌（如席藻属（Lyngbya）、微鞘藻属（Microcoleus））在氢气输出过程中发挥了关键作用；同时，丰度相对较低的产甲烷古菌（methanogens）与硫酸盐还原菌（sulfate reducers）同样对该过程具有重要意义。