Volatile-mediated interactions between phylogenetically different soil bacteria.

Paolina Garbeva,Cornelis Hordijk,Wietse De Boer,Saskia Gerards

doi:10.3389/fmicb.2014.00289

Paolina Garbeva, Cornelis Hordijk + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2014.00289

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Abstract

There is increasing evidence that organic volatiles play an important role in interactions between micro-organisms in the porous soil matrix. Here we report that volatile compounds emitted by different soil bacteria can affect the growth, antibiotic production and gene expression of the soil bacterium Pseudomonas fluorescens Pf0–1. We applied a novel cultivation approach that mimics the natural nutritional heterogeneity in soil in which P. fluorescens grown on nutrient-limited agar was exposed to volatiles produced by 4 phylogenetically different bacterial isolates (Collimonas pratensis, Serratia plymuthica, Paenibacillus sp., and Pedobacter sp.) growing in sand containing artificial root exudates. Contrary to our expectation, the produced volatiles stimulated rather than inhibited the growth of P. fluorescens. A genome-wide, microarray-based analysis revealed that volatiles of all four bacterial strains affected gene expression of P. fluorescens, but with a different pattern of gene expression for each strain. Based on the annotation of the differently expressed genes, bacterial volatiles appear to induce a chemotactic motility response in P. fluorescens, but also an oxidative stress response. A more detailed study revealed that volatiles produced by C. pratensis triggered, antimicrobial secondary metabolite production in P. fluorescens. Our results indicate that bacterial volatiles can have an important role in communication, trophic - and antagonistic interactions within the soil bacterial community.

Highlights

Most soil bacteria occur in multi-species communities, in which a variety of interactions influences their behavior and performance
Volatiles produced by C. pratensis and S. plymuthica stimulated the growth of P. fluorescens, whereas volatiles emitted by Paenibacillus sp., Pedobacter sp. and the mix of all 4 bacteria did not affect P. fluorescens growth
TEST OF PURE INDIVIDUAL VOLATILES Several volatiles produced by Collimonas pratensis Ter91 and Serratia plymuthica PRI-2C were commercially available

Summary

Introduction

Most soil bacteria occur in multi-species communities, in which a variety of interactions influences their behavior and performance. Recent years have shown an explosion of research on “communication” between different soil bacterial species (Keller and Surette, 2006; Ryan and Dow, 2008; Shank and Kolter, 2009; Garbeva et al, 2011b). The gaseous phase forms an integral part of the natural surroundings of soil microorganisms. Volatile molecules can act over a wider range of scale than non-volatiles as they can diffuse through both the liquid and gaseous phases of the soil (Effmert et al, 2012). Volatiles are thought to play an important role in communication and competition between physically separated soil microorganisms (Kai et al, 2009; Chernin et al, 2011; Garbeva et al, 2011a, 2014; Effmert et al, 2012)

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