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Antagonism between bacteria and fungi: substrate competition and a possible trade-off between fungal growth and tolerance towards bacteria
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
(English)Article in journal (Refereed) Submitted
URN: urn:nbn:se:uu:diva-92968OAI: oai:DiVA.org:uu-92968DiVA: diva2:166304
Available from: 2005-04-29 Created: 2005-04-29 Last updated: 2014-07-14Bibliographically approved
In thesis
1. Interactions between Bacteria and Fungi on Aquatic Detritus – Causes and Consequences
Open this publication in new window or tab >>Interactions between Bacteria and Fungi on Aquatic Detritus – Causes and Consequences
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacteria and fungi dominate the decomposition of aquatic plants, a major process in the carbon and nutrient cycling in many aquatic systems. Although phylogenetically distant, bacteria and fungi often live in close proximity with each other. Since these microorganisms also have similar ecological functions, interactions have developed between them. This thesis explores the nature of such interactions, and the potential effects on key components of the decomposition process. The thesis includes a critical assessment of the ergosterol method for determination of fungal biomass, a survey of the environmental factors determining the distribution and taxa numbers of litter-decomposing bacteria and fungi in lakes, and a number of experiments on the interactions between bacteria and fungi. In all the experiments performed, fungi responded to bacterial presence through antagonism, although different fungal strains, bacterial communities and substrates were used. The antagonism seemed to be caused by interference competition for substrate. The fungal effect on bacteria was less consistent. Bacterial growth was suppressed, unaffected, or even enhanced by the presence of fungi. Fungi contributed more to extracellular enzyme production than bacteria, and bacteria were probably able to assimilate intermediate decomposition products formed through the activity of extracellular enzymes of fungal origin. Thus, the effect on bacteria from interacting with fungi was determined by the balance between competition and benefit from excreted enzymes. Bacteria and fungi also used different size fractions of the organic matter, according to their different enzymatic capacities. Hence, bacteria appeared to assimilate low-molecular-weight compounds, while high-molecular-weight compounds were utilized primarily by fungi.

In brief, the ecological interactions influenced the growth and hence also the biomass development of bacteria and fungi, which affected enzyme activity as well as utilization of dissolved organic matter. Therefore, I suggest that interactions between bacteria and fungi influence degradation of plant litter in aquatic systems.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. 42 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 46
Ecology, bacteria, fungi, decomposition, antagonism, extracellular enzymes, competition, macrophytes, dissolved organic carbon (DOC), ergosterol, Ekologi
National Category
urn:nbn:se:uu:diva-5771 (URN)91-554-6231-6 (ISBN)
Public defence
2005-05-20, Ekmansalen, Kärnhuset, EBC, Norbyv. 14, Uppsala, 10:00
Available from: 2005-04-29 Created: 2005-04-29Bibliographically approved

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Tranvik, Lars J.
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