MARINE OSCILLATORIA (TRICHODESMIUM) - EXPLANATION FOR AEROBIC NITROGEN-FIXATION WITHOUT HETEROCYSTS
MARINE OSCILLATORIA (TRICHODESMIUM) - EXPLANATION FOR AEROBIC NITROGEN-FIXATION WITHOUT HETEROCYSTS
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DOI：
10.1126/science.1257749
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发表时间：
1976-01-01
期刊：
影响因子：
56.9
通讯作者：
PRICE, CC
中科院分区：
文献类型：
--
作者：
CARPENTER, EJ;PRICE, CC
海洋振荡藻[种]的固氮作用似乎与位于菌落中心的分化细胞有关。这些中心细胞相对于外围细胞表现出较少的色素沉着，并且在光合作用中不吸收二氧化碳。中心细胞显然不会产生使氮酶失活的氧。当中心细胞通过破坏菌落暴露于O2时，即使单个毛状体保持完整，N2固定（乙炔还原）也会急剧减少。在没有氧气的情况下，菌落的破坏不会导致氮酶活性的降低。在海洋中，波浪作用产生的湍流明显地分离了毛状体，使氧气进入，从而降低了氮酶的活性。这些观察结果解释了振荡藻在有氧环境中如何能够在没有异囊的情况下固定N2，以及为什么它的繁殖几乎总是发生在平静的海洋中。
N fixation in marine Oscillatoria [spp.] appears to be associated with differentiated cells located in the center of the colony. These central cells exhibit reduced pigmentation relative to peripherally located cells and do not incorporate 14CO2 in photosynthesis. Central cells apparently do not produce O2 which would deactivate nitrogenase. When central cells are exposed to O2 via disruption of the colonies, N2 fixation (acetylene reduction) decreases sharply even though individual trichomes remain intact. Disruption of colonies in the absence of O2 does not cause reduced nitrogenase activity. In the sea, turbulence from wave action apparently separates trichomes allowing O2 to enter thus decreasing nitrogenase activity. These observations explain how Oscillatoria [erythraea] is able to fix N2 without heterocysts in an aerobic environment and why its blooms virtually always occur in calm seas.