Diurnal redox fluctuation and microbial activity in the rhizosphere of wetland plants
2008 (English)In: European journal of soil biology, ISSN 1164-5563, Vol. 44, no 3, 324-333 p.Article in journal (Refereed) Published
Wetland plants release oxygen through the aerenchyma system to the roots, providing oxic habitats in the rhizosphere. The consumption of the oxygen during the night establishes a diurnal fluctuation of the redox conditions (-320 mV to +300 mV) that explains the coexistence of aerobic and anaerobic microorganisms in the rhizosphere. The redox fluctuation and its effect on the activity of rhizosphere microorganisms were investigated by RNA-based fingerprinting techniques in a laboratory scale reactor planted with Juncus effusus. The denaturing gradient gel electrophoresis (DGGE) patterns of 16S rRNA obtained with "universal" primers were very similar regardless of the time of sampling, indicating that the overall ribosome level of the predominantly active members did not change significantly. The amoA transcript DGGE patterns showed moderate diurnal dynamics with specific bands observed either in day or night samples. However, the majority of amoA genes were continuously expressed, indicating that the activity of functional genes may only partly be a measure sensitive enough for tracing the physiological activity on a short time scale. The results indicate that loose regulation of functional genes can be the main strategy for accommodation to fluctuating environmental conditions. The spatial separation of microbial activities as a result of diurnal fluctuating oxygen availability probably contributes to niche differentiation in the rhizosphere but this is difficult to track it at transcriptome level. Â© 2008 Elsevier Masson SAS. All rights reserved.
Place, publisher, year, edition, pages
2008. Vol. 44, no 3, 324-333 p.
Microbial activity, Nitrification, Redox fluctuation, Rhizosphere
IdentifiersURN: urn:nbn:se:uu:diva-224292DOI: 10.1016/j.ejsobi.2008.01.003OAI: oai:DiVA.org:uu-224292DiVA: diva2:716305