This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Binnerup, S J Articles by Sørensen, J Search for Related Content PubMed PubMed Citation Articles by Binnerup, S J Articles by Sørensen, J Agricola Articles by Binnerup, S J Articles by Sørensen, J

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1992 August; 58(8): 2375-2380

Nitrate and nitrite microgradients in barley rhizosphere as detected by a highly sensitive denitrification bioassay.

Department of Ecology and Molecular Biology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.

ABSTRACT

A highly sensitive denitrification bioassay was developed for detection of NO3- and NO2- in rhizosphere soil samples. Denitrifying Pseudomonas aeruginosa ON12 was grown anaerobically in citrate (30 mM) minimal medium with KClO3 (10 mM) and NaNO2 (3 mM), which gave cells capable of NO2- reduction to N2O but incapable of NO3- reduction to NO2-. Growth on citrate minimal medium further resulted in the absence of N2O reduction. When added to small soil samples in O2-free vials, such cells could be used to convert the indigenous NO2- pool to N2O, which was subsequently quantified by gas chromatography. Cells grown in KClO3-free citrate medium with 10 mM NaNO3 as the electron acceptor were capable of reducing both NO3- and NO2-, and these cells could subsequently be added to the sample to convert the indigenous NO3- pool to N2O. Concentrations of both NO3- and NO2- were thus determined as N2O, with a detection limit of approximately 10 pmol of N. The bioassay could be used to determine NO3- and NO2- pools in 10-mg soil samples taken along a microgradient in the rhizosphere of field-grown barley plants. At both low (10%, wt/wt) and high (18%, wt/wt) water content, relatively high levels of NO2- were found in the rhizosphere compared with bulk soil. Under dry conditions, NO3- was also more abundant in the rhizosphere than in the bulk soil, whereas such a difference was not observed at the high water content. The roles of plant metabolism and bacterial nitrification and denitrification processes for NO3- and NO2- availability in the rhizosphere are discussed.

This article has been cited by other articles:

• Pothier, J. F., Wisniewski-Dye, F., Weiss-Gayet, M., Moenne-Loccoz, Y., Prigent-Combaret, C. (2007). Promoter-trap identification of wheat seed extract-induced genes in the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp245. Microbiology 153: 3608-3622 [Abstract] [Full Text]  
• Baek, S.-H., Shapleigh, J. P. (2005). Expression of Nitrite and Nitric Oxide Reductases in Free-Living and Plant-Associated Agrobacterium tumefaciens C58 Cells. Appl. Environ. Microbiol. 71: 4427-4436 [Abstract] [Full Text]  
• Bethke, P. C., Badger, M. R., Jones, R. L. (2004). Apoplastic Synthesis of Nitric Oxide by Plant Tissues. Plant Cell 16: 332-341 [Abstract] [Full Text]  
• Højberg, O., Schnider, U., Winteler, H. V., Sørensen, J., Haas, D. (1999). Oxygen-Sensing Reporter Strain of Pseudomonas fluorescens for Monitoring the Distribution of Low-Oxygen Habitats in Soil. Appl. Environ. Microbiol. 65: 4085-4093 [Abstract] [Full Text]