The nitrogen physiology of the marine N₂-fixing cyanobacteria Trichodesmium spp.

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• 作者：Mulholland ; Margaret R. ; Capone ; Douglas G.
• 关键词：Plant science ; Cell biology ; Nitrogen-fixation ; Cyanobacteria ; Nitrate ; Nitrite
• 刊名：Trends in Plant Science
• 出版年：2000
• 出版时间：April 1, 2000
• 年：2000
• 卷：5
• 期：4
• 页码：148-153
• 全文大小：111 K

文摘

Trichodesmium spp. have proved to be enigmatic organisms, and their ecology and physiology are unusual among diazotrophs. Recent research shows that they can simultaneously fix N₂ and take up combined nitrogen. The co-occurrence of these two processes is thought to be incompatible, but they could be obligatory in Trichodesmium spp. if only a small fraction of cells within a colony or along a filament are capable of N₂ fixation. Combined nitrogen is released from cells during periods of active growth and N₂ fixation, and concomitantly taken up by Trichodesmium spp. or cells living in association with colonies. Although the nitrogenase of Trichodesmium spp. is affected by high concentrations of combined nitrogen, it might be relatively less sensitive to low concentrations of combined nitrogen typical of the oligotrophic ocean and culture conditions. Nitrogenase activity and synthesis exhibits an endogenous rhythm in Trichodesmium spp. cultures, which is affected by the addition of nitrogen.