Physiological and molecular characterisation of microbial communities associated with different water-stable aggregate size classes

We determined if the structure and function of microbial communities associated with different aggregate size classes was influenced when the aggregate formation occurred under either nitrogen (N) limitation (straw only incubation treatment) or carbon (C) limitation (straw+N incubation treatment). U...

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Bibliographic Details
Published in:	Soil biology & biochemistry Vol. 37; no. 11; pp. 2007 - 2016
Main Authors:	Väisänen, R.K., Roberts, M.S., Garland, J.L., Frey, S.D., Dawson, L.A.
Format:	Journal Article
Language:	English
Published:	Oxford Elsevier Ltd 01-11-2005 New York, NY Elsevier Science
Subjects:	Aggregation agricultural soils Agronomy. Soil science and plant productions Bacteria BD oxygen biosensor bioassays Biochemistry and biology biodiversity Biological and medical sciences carbon Chemical, physicochemical, biochemical and biological properties CLPP community structure ecological function Fundamental and applied biological sciences. Psychology Fungi Microbial communities Nitrogen nitrogen content Organic matter Physical fractionation Physics, chemistry, biochemistry and biology of agricultural and forest soils restriction fragment length polymorphism silt loam soils soil aggregates soil aggregation soil microorganisms Soil organic matter soil respiration Soil science T-RFLP Aggregation Fungi Physical fractionation CLPP T-RFLP Soil organic matter Bacteria BD oxygen biosensor Microbial communities Nitrogen Fractionation Organic matter Oxygen Physical properties Molecular parameter Soils Restriction fragment length polymorphism Biosensor Physiology Soil science Aggregate Microbial community Thallophyta
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Summary:	We determined if the structure and function of microbial communities associated with different aggregate size classes was influenced when the aggregate formation occurred under either nitrogen (N) limitation (straw only incubation treatment) or carbon (C) limitation (straw+N incubation treatment). Using a combination of community-level physiological (BD Oxygen Biosensor assay) and molecular (terminal restriction fragment length polymorphism; T-RFLP) profiling methods, we found differences in both microbial community composition and the physiological response of these communities between different aggregate size classes. The response of fungal and bacterial communities to ‘straw only’ and ‘straw+N’ treatments differed in that bacterial community composition was affected by the treatments, whereas fungal community composition was not. The magnitude of change in the bacterial community response increased with decreasing aggregate size. However, there were no significant differences in the mean bacterial community richness (number of different terminal restriction fragments; TRFs) between different aggregate size classes for the two treatments. In general, microbial communities associated with larger aggregate size fractions (large and small macroaggregates) were found to have a significantly faster respiratory response than the communities associated with microaggregates. Application of the fungal inhibitor cycloheximide resulted in a significant reduction in the utilization of cellulose, chitin, mannose, xylan, and xylose by the microbial communities associated with all aggregate size classes, indicating that fungi are significant contributors to the utilization of these compounds. Our results demonstrate that the BD Oxygen Biosensor assay offers a valuable new tool for community level physiological profiling. When used in combination with census-based methods such as T-RFLP, a greater level of resolution can be achieved.
ISSN:	0038-0717 1879-3428
DOI:	10.1016/j.soilbio.2005.02.037