Transcriptional and antagonistic responses of Pseudomonas fluorescens Pf0-1 to phylogenetically different bacterial competitors

Abstract

The ability of soil bacteria to successfully compete with a range of other microbial species is crucial for their growth and survival in the nutrient-limited soil environment. In the present work, we studied the behavior and transcriptional responses of soil-inhabiting Pseudomonas fluorescens strain Pf0-1 on nutrient-poor agar to confrontation with strains of three phylogenetically different bacterial genera, that is, Bacillus, Brevundimonas and Pedobacter. Competition for nutrients was apparent as all three bacterial genera had a negative effect on the density of P. fluorescens Pf0-1; this effect was most strong during the interaction with Bacillus. Microarray-based analyses indicated strong differences in the transcriptional responses of Pf0-1 to the different competitors. There was higher similarity in the gene expression response of P. fluorescens Pf0-1 to the Gram-negative bacteria as compared with the Gram-positive strain. The Gram-negative strains did also trigger the production of an unknown broad-spectrum antibiotic in Pf0-1. More detailed analysis indicated that expression of specific Pf0-1 genes involved in signal transduction and secondary metabolite production was strongly affected by the competitors' identity, suggesting that Pf0-1 can distinguish among different competitors and fine-tune its competitive strategies. The results presented here demonstrate that P. fluorescens Pf0-1 shows a species-specific transcriptional and metabolic response to bacterial competitors and provide new leads in the identification of specific cues in bacteria-bacteria interactions and of novel competitive strategies, antimicrobial traits and genes.

Interspecies competition triggers virulence and mutability in Candida albicans–Pseudomonas aeruginosa mixed biofilms

“…Microbial biofilms represent heterogeneous populations of species that form intimate contacts. Within these populations, species communicate, cooperate and compete (Davey and O'toole, 2000;Tyson et al, 2004;Hansen et al, 2007;Harrison et al, 2008;Garbeva et al, 2011). Some of these microbial interactions are beneficial, and some are detrimental from a human standpoint (Hughes and Kim, 1973;Lynch and Robertson, 2008).…”

Antibiotic Resistance in Co-Culture Biofilm of <i>Listeria monocytogenes</i> J0161

“…In a co-existing state almost always, every individual microbe is bound to affect the existence of the other, either symbiotically or antagonistically (Alexander, 1974;Nadel et al, 2009 (Zhoa et al, 2004) and the influence of Staphylococcus aureus on the population of L. monocytogenes, that positively affected the existence of L. monocytogenes (Rieu et al, 2008) have been reported lately. Despite such reports, the molecular mechanism behind the conflict or co-operation within a microbial community in general had not been taken to research till recently (Garbeva et al, 2011).…”

Protozoa stimulate the plant beneficial activity of rhizospheric pseudomonads

“…However, in natural settings bacteria are interacting with several organisms. As the physiology of beneficial microbes is strongly influenced by biotic interactions (Dubuis et al 2007;Mazzola et al 2009;Jousset and Bonkowski 2010;Garbeva et al 2011), we tested whether integrating other organisms could alter the bacterial effect on plant growth and pathogen inhibition.…”