文章基本信息

标题：An Asymbiotic Nitrogen-Fixing Bacterium from the Root Environment of Corn
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作者：P. N. Raju ; Harold J. Evans ; Ramon J. Seidler 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：11
页码：3474-3478
DOI：10.1073/pnas.69.11.3474
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Examination of root systems and adhering soil associated with unusually green corn plants from nitrogen-deficient areas in fields has revealed higher acetylene-reducing activities than comparable root systems of chlorotic plants that appeared to be nitrogen deficient. From the root systems with acetylene-reducing activity, N2-fixing Enterobacter cloacae were isolated. Pure cultures of the organism grown in a medium lacking added fixed nitrogen reduced acetylene to ethylene and used N2 as a sole source of nitrogen under anaerobic conditions. Acetylene reduction was strikingly inhibited by 0.04 atm or greater partial pressures of O2; however, the bacteria maintained appreciable acetylene-reducing rates in medium exposed to partial pressures of O2 ranging from 0.005 to 0.015 atm. Nitrogenase activity in cell-free extracts of the bacterium was dependent upon Na2S2O4 and an ATP-generating system. Some environmental conditions expected to influence N2 fixation by free-living N2-fixing bacteria on root surfaces of nonlegumes are discussed.
关键词：Enterobacter cloacae ; acetylene reduction ; nonleguminous plants