Pinto-Tomás Adrián A, Anderson Mark A, Suen Garret, Stevenson David M, Chu Fiona S T, Cleland W Wallace, Weimer Paul J, Currie Cameron R
Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706, USA.
Science. 2009 Nov 20;326(5956):1120-3. doi: 10.1126/science.1173036.
Bacteria-mediated acquisition of atmospheric N2 serves as a critical source of nitrogen in terrestrial ecosystems. Here we reveal that symbiotic nitrogen fixation facilitates the cultivation of specialized fungal crops by leaf-cutter ants. By using acetylene reduction and stable isotope experiments, we demonstrated that N2 fixation occurred in the fungus gardens of eight leaf-cutter ant species and, further, that this fixed nitrogen was incorporated into ant biomass. Symbiotic N2-fixing bacteria were consistently isolated from the fungus gardens of 80 leaf-cutter ant colonies collected in Argentina, Costa Rica, and Panama. The discovery of N2 fixation within the leaf-cutter ant-microbe symbiosis reveals a previously unrecognized nitrogen source in neotropical ecosystems.
细菌介导的大气氮获取是陆地生态系统中氮的关键来源。在此，我们揭示共生固氮作用促进了切叶蚁对特殊真菌作物的培育。通过乙炔还原和稳定同位素实验，我们证明了八种切叶蚁的菌圃中发生了固氮作用，并且进一步证明这种固定的氮被纳入了蚂蚁的生物量中。从阿根廷、哥斯达黎加和巴拿马采集的80个切叶蚁蚁群的菌圃中持续分离出共生固氮细菌。切叶蚁 - 微生物共生关系中固氮作用的发现揭示了新热带生态系统中一个此前未被认识的氮源。
