PARUKO, R. A., and P. W. WILSON. 1970. Regulation of nitrogenase synthesis by Klebsiellapr~e~irrroniae.Can. J. Microbial. 16: 681-685. The synthesis of the nitrogenase system in Nz-fixing bacteria is repressed when the organisms are grown on NH4+-N. It has not been unequivocally determined, however, if N2 is necessary for induction in NH4+-deficient cultures. Previous experiments with Klebsiella ptre~itr~ot~iae, Azotohacter vinelandii, Closrridium pasteuriatzllm, and Rl~odospirillvm r~rbrlim have been inconclusive owing to inadequacy of the methods, primarily the presence of Nz as a contaminant in the gases used. Results of experiments described in this paper using cultures of K. pnellmorziae M5al grown under both limited N2 and in its apparent absence indicate that the control of nitrogenase is most likely through simple repression by NH4+ o r by an incorporation product, e.g., glutamine.
THE need for a rapid, accurate method of estimating carbon dioxide is common to many branches of science. A large number of studies in both theoretical and applied chemistry demand simple methods for determining small percentages of carbon dioxide in air and other gaseous mixtures. It is not surprising
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