Co-Cultures ofPseudomonas aeruginosaandRoseobacter denitrificansReveal Shifts in Gene Expression Levels Compared to Solo Cultures

Crystal A Conway,Nwadiuto Esiobu,Jose V Lopez

doi:10.1100/2012/120108

Crystal A Conway, Nwadiuto Esiobu + Show 1 more

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https://doi.org/10.1100/2012/120108

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Abstract

Consistent biosynthesis of desired secondary metabolites (SMs) from pure microbial cultures is often unreliable. In a proof-of-principle study to induce SM gene expression and production, we describe mixed “co-culturing” conditions and monitoring of messages via quantitative real-time PCR (qPCR). Gene expression of model bacterial strains (Pseudomonas aeruginosa PAO1 and Roseobacter denitrificans Och114) was analyzed in pure solo and mixed cocultures to infer the effects of interspecies interactions on gene expression in vitro, Two P. aeruginosa genes (PhzH coding for portions of the phenazine antibiotic pathway leading to pyocyanin (PCN) and the RhdA gene for thiosulfate: cyanide sulfurtransferase (Rhodanese)) and two R. denitrificans genes (BetaLact for metallo-beta-lactamase and the DMSP gene for dimethylpropiothetin dethiomethylase) were assessed for differential expression. Results showed that R. denitrificans DMSP and BetaLact gene expression became elevated in a mixed culture. In contrast, P. aeruginosa co-cultures with R. denitrificans or a third species did not increase target gene expression above control levels. This paper provides insight for better control of target SM gene expression in vitro and bypass complex genetic engineering manipulations.

Highlights

Interactions among diverse microbial species are dynamic and most likely propel many of the adaptations that allow the occupation of diverse niches that can range from biofilms to host digestive tracts to multiple marine habitats [1, 2]
A housekeeping gene, DNA directed RNA polymerase (RNA pol), subunit alpha expression appeared constant throughout all quantitative real-time PCR (qPCR) runs meaning their expression level was unaffected by the experimental conditions
Gene Expression Patterns Seen in P. aeruginosa and R. denitrificans Co-Cultures

Summary

Introduction

Interactions among diverse microbial species are dynamic and most likely propel many of the adaptations that allow the occupation of diverse niches that can range from biofilms to host digestive tracts to multiple marine habitats [1, 2]. These interactions among diverse bacteria can be either beneficial such as in symbioses with eukaryotic hosts [3, 4] or antagonistic due to competition within multiple species microcosms [5]. SMs are used for defense, chemical signaling, and host-microbe interactions [6, 7]. Pure cultures of microbes often fail to yield reliable or consistent biosynthesis of SMs [9]

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