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Nitrogenase activity in cyanobacteria measured by the acetylene reduction assay: a comparison between batch incubation and on-line monitoring

Staal, M.J. and te Lintel-Hekkert, S. and Harren, F.J.M. and Stal, L.J. (2001) Nitrogenase activity in cyanobacteria measured by the acetylene reduction assay: a comparison between batch incubation and on-line monitoring. Environmental Microbiology, 3, 343-351. ISSN 1462-2912.

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Official URL: http://dx.doi.org/10.1046/j.1462-2920.2001.00201.x

Abstract

A new on-line method for measuring acetylene reduction is described. It consists of a gas-flow cell connected to an electronic gas-mixing system and an automatic sample loop in the gas chromatograph. Alternatively, ethylene can be determined by using laser-based trace gas detection. The laser- based trace gas detection technique achieves a detection limit that is three orders of magnitude better than gas chromatography. We have applied the on-line method to the measurement of nitrogen fixation in a culture of the heterocystous cyanobacterium Nodularia spumigena and compared it with conventional batch-type incubations. Incubation of N. spumigena in the gas-flow cell resulted in very short response times with a steady-state flux of ethylene obtained within 2 min. Nitrogenase was shown to respond immediately to changes in light and oxygen. Monitoring of nitrogenase activity could be continued for several hours without having a negative impact on nitrogen fixation rates in N. spumigena. This was not the case in batch incubations, in which changes in nitrogenase activities were recorded during incubations, probably as a result of varying oxygen concentrations. It was therefore concluded that the on-line method is superior to batch incubations when rates of nitrogenase activity are to be measured. The method is suitable for natural samples (water or sediment). [KEYWORDS: N-2 fixation; o-2]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11070
Deposited On:24 Nov 2011 01:00
Last Modified:31 Mar 2014 10:05

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