Rapid changes in the rhizosphere bacterial community structure during re-colonization of sterilized soil
Diversity has been shown to be pivotal in ecosystem stability and resilience. It is therefore important to increase our knowledge about the development of diversity. The aim of this study was to investigate the temporal dynamics of the bacterial community structure in the rhizosphere of wheat plants growing in a soil in which the initial conditions for bacterial re-colonization were modified by mixing different amounts of sterilized with native soil at ratios of 19:1, 9:1, 4:1 and 1:1. Additional treatments comprised sterilized soil or native soil. Plant dry weight at day 20 decreased with increasing percentage of native soil in the mix. The bacterial community structure in the rhizosphere was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) at days 3, 14 and 20 after planting. The bacterial community in the sterilized soil had a lower diversity and evenness than the native soil. Both diversity and evenness increased with time in the sterilized soil. Community structure in the different mixes changed over time and the changes were mix-specific. Principal component analyses of the DGGE banding patterns showed clear differences between the treatments particularly at day 3 and day 14 and revealed changes in community structure within a few days in a given treatment. The results of the present study show that bacterial communities rapidly re-colonize sterilized soil. During re-colonization, the community structure changes rapidly with a general trend towards higher diversity and evenness. The changes in community structure over time are also affected by the amount of sterile substrate to be re-colonized.
KeywordsSuccession Bacterial community structure Denaturing gradient gel electrophoresis Diversity Rhizosphere
We would like to thank Prof. Reinhard Lieberei from the Institute for Applied Botany, University of Hamburg, Germany for his support.
- Griffiths BS, Ritz K, Bardgett RD, Cook R, Ekelund F, Sørensen SJ, Bååth E, Bloem J, De Ruiter PC, Dolfing J, Nicolardot B (2000) Ecosystem response of pasture soil communities to fumigation-induced microbial diversity reductions: an examination of the biodiversity-ecosystem function relationship. Oikos 90:279–294Google Scholar
- Khaliq A, Sanders FE (1998) Effects of vesicular arbuscular mycorrhizal inoculation on growth and phosphorus nutrition of barley in natural and methyl bromide treated soil. J Plant Nutr 21:2163–2177Google Scholar
- McGrady-Steed J, Harris PM, Morin PJ (1997) Biodiversity regulates ecosystem predictability. Nature 390:162–165Google Scholar
- Odum EP (1954) Fundamentals of ecology. Saunders, Philadelphia, Pa.Google Scholar
- Olff H, Hoorens B, De Goede RGM, Van der Putten WH, Gleichman, JM (2000) Small-scale shifting mosaic of two dominant grassland species: the possible role of soil-borne pathogens. Oecologia 125:45–54Google Scholar
- Otabong E, Barbolina I (1998) Changes in solubility of various phosphorus fractions promoted by autoclaving soil and sewage sludge. Swed J Agric Res 28:129–135Google Scholar
- Ponge JF (1991) Succession of fungi and fauna during decomposition of needles in a small area of Scots pine litter. Plant Soil 138:99–113Google Scholar
- Powlson DS, Jenkinson DS (1976) The effects of biocidal treatments on metabolism in soil. II. Gamma irradiation, autoclaving, air-drying and fumigation. Soil Biol Biochem 8:179–188Google Scholar
- Sparling GP, Berrow ML (1985) Effect of air-drying, γ-irradiation and chloroform fumigation of soil on extractability of trace elements. J Agric Res 104:223–226Google Scholar
- Van der Heijden MGA, Klironomos JN, Ursic M, Moutoglis P, Streitwolf-Engel R, Boller T, Wiemken A, Sanders IR (1998) Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability and productivity. Nature 398:69–72Google Scholar