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Interactions between soil bacteria and arbuscular mycorrhizal fungi

Toljander, Jonas (2006). Interactions between soil bacteria and arbuscular mycorrhizal fungi. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2006:39
ISBN 91-576-7088-9
[Doctoral thesis]

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The extraradical mycelium (ERM) of mycorrhizal fungi constitutes an important pathway for the translocation of energy-rich photoassimilates from plant to soil. Because of the large surface of the mycelium, and its provision of carbon, the ERM potentially constitutes an important site for interactions with other microorganisms in soils. The focus of this thesis is on the ERM of arbuscular mycorrhizal (AM) fungi and its interactions with soil bacteria, and the possible ecological significance of these interactions. In an in vitro study, soil bacteria differed in their ability to attach to AM fungal hyphae. These physical associations between bacteria and fungi were influenced by hyphal vitality and fungal strain. The degree of attachment of bacteria to living or dead hyphae may reflect the ecological niche differentiation of these bacteria, and consequently their trophic relationship (e.g. mutualistic or saprotrophic) to the mycorrhizal fungi. Carbohydrates of mycelial origin, mainly in the form of glucose, acetate and formiate, were identified in exudates from an AM fungus. Mycelial exudates promoted the occurrence of certain bacterial taxa in vitro, further supporting the view that specific interactions may occur between some bacteria and AM fungi. In a field study with long-term applications of different organic and inorganic fertilisers, amendments with sewage sludge or ammonium sulphate changed the bacterial community composition in root-associated soil aggregates. In addition, ammonium sulphate reduced the taxon richness and the occurrence of specific taxa of both AM fungi and bacteria in the mycorrhizosphere. These changes were primarily explained by the low pH of soils amended with sewage sludge or ammonium sulphate. However, taxon richness of both AM fungi and bacteria also appeared to be promoted by high soil organic content. In summary, interactions between bacteria and the ERM of AM fungi may be specific and physical associations and mycelial exudates may influence these interactions. Microbial interactions are important in determining soil fertility and plant health. In agricultural systems some microorganisms may be either positively or negatively affected by different types of fertilisation, therefore it is possible soil management practices could be customised to promote microorganisms that are beneficial to farming systems.

Authors/Creators:Toljander, Jonas
Title:Interactions between soil bacteria and arbuscular mycorrhizal fungi
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :May 2006
Number of Pages:39
ALLI. Johansson, J.F., Paul, L.R. & Finlay, R.D. 2004. Microbial interactions in the mycorrhizosphere and their significance for sustainable agriculture. FEMS Microbiology Ecology 48, 1-13. II. Toljander, J.F., Artursson, V., Paul, L.R., Jansson, J.K. & Finlay, R.D. 2006. Attachment of different soil bacteria to arbuscular mycorrhizal fungal extraradical hyphae is determined by hyphal vitality and fungal species. FEMS Microbiology Letters 254, 34-40. III. Toljander, J.F., Lindahl, B.D., Paul, L.R., Elfstrand, M. & Finlay, R.D. Effects of mycelial exudates from an arbuscular mycorrhizal fungus on soil bacterial community composition in vitro. Submitted manuscript. IV. Toljander, J.F., Santos, J., Tehler, A. & Finlay, R.D. Community composition of arbuscular mycorrhizal fungi and bacteria in the maize mycorrhizosphere in a long-term fertilisation trial. Manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-7088-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P34 Soil biology
Subjects:Not in use, please see Agris categories
Agrovoc terms:vesicular arbuscular mycorrhizae, mycelium, bacteria, soil, microbial ecology, soil fertility
Keywords:arbuscular mycorrhiza (AM), extraradical mycelium (ERM), hyphosphere, interactions, mycorrhizosphere, soil bacteria, sustainable agriculture, TRFLP
Permanent URL:
ID Code:1134
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Jonas Toljander
Deposited On:23 May 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

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