J. Phys. IV France
Volume 125, June 2005
Page(s) 31 - 33

J. Phys. IV France 125 (2005) 31-33

DOI: 10.1051/jp4:2005125008

Application of the photoacoustic method to the measurement of acetylene reduction by nitrogenase enzyme

D.U. Schramm1, M.S. Sthel1, L.O. Carneiro1, A.A. Franco2, A.C. Campos3 and H. Vargas1

1  Centro de Ciência e Tecnologia, Av. Alberto Lamego 2000, Campos dos Goytacazes, RJ 28015-620, Brazil
2  Embrapa-CNPAB, PO Box 74.505, Universidade Estadual do Norte Fluminense Seropédica, RJ 23851-970, Brazil
3  Centro de Ciências e Tecnologias Agropecuárias, Brazil

Nitrogenase is an enzyme responsible for the reduction of the atmospheric N2 into NH4+, which represents the key entry point of the molecular nitrogen into the biogeochemical cycle of nitrogen. This enzyme is present in the rhizobial bacteroids, which are symbionts in a Leguminosae plant (Acacia Holosericea), and also reduces acetylene into ethylene at the same rate as the nitrogen reduction. Therefore, a CO2 Laser Photoacoustic system was used for detecting and monitoring the ethylene emission by the nitrogenase activity, in the rhizobial symbionts in Acacia Holosericea, when they are confined in test tubes with acetylene at two different volumes (0.1 and 0.5 ml). Ethylene concentrations are also determined in the ppm range.

© EDP Sciences 2005