Microbial diversity determines the invasion of soil by a bacterial pathogen
- aDepartment of Microbial Ecology, Center for Evolutionary and Ecological Studies, University of Groningen, 9700 CC, Groningen, The Netherlands; and
- bBiology Center, Academy of Sciences of the Czech Republic (AS CR), Public Research Institution (v.v.i.), Institute of Soil Biology, CZ-370 05 České Budějovice, Czech Republic
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Edited by Steven E. Lindow, University of California, Berkeley, CA, and approved December 12, 2011 (received for review June 23, 2011)

Abstract
Natural ecosystems show variable resistance to invasion by alien species, and this resistance can relate to the species diversity in the system. In soil, microorganisms are key components that determine life support functions, but the functional redundancy in the microbiota of most soils has long been thought to overwhelm microbial diversity–function relationships. We here show an inverse relationship between soil microbial diversity and survival of the invading species Escherichia coli O157:H7, assessed by using the marked derivative strain T. The invader's fate in soil was determined in the presence of (i) differentially constructed culturable bacterial communities, and (ii) microbial communities established using a dilution-to-extinction approach. Both approaches revealed a negative correlation between the diversity of the soil microbiota and survival of the invader. The relationship could be explained by a decrease in the competitive ability of the invader in species-rich vs. species-poor bacterial communities, reflected in the amount of resources used and the rate of their consumption. Soil microbial diversity is a key factor that controls the extent to which bacterial invaders can establish.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: j.d.van.elsas{at}rug.nl.
Author contributions: J.D.v.E. and J.F.S. designed research; M.C., C.A.M., D.E., and V.K. performed research; J.D.v.E. and J.F.S. analyzed data; and J.D.v.E. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1109326109/-/DCSupplemental.
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