Project description:Bacteria that inhabit the rhizosphere of agricultural crops can have a beneficial effect on crop growth, including through the solubilisation and remineralisation of complex forms of phosphorus (P). However[1], our understanding of the bacterial proteomic response to P stress is limited. Here, exoproteomic analysis of three Pseudomonas species was performed in unison[2] with proteomic analysis of Pseudomonas putida BIRD-1 (BIRD-1) grown [3] under P replete and P deplete conditions. Comparative exoproteomics revealed marked heterogeneity in the exoproteomes of each Pseudomonas species in response to low concentrations of P. In addition to well-characterised members of the PHO regulon such as alkaline phosphatases, several previously undiscovered proteins are responsive to phosphate depletion including putative nucleases, phosphotriesterases, putative phosphonate transporters and outer membrane proteins. Moreover, in BIRD-1, mutagenesis of the master regulator, phoBR, led us to confirm the addition of several novel PHO- dependent proteins. Our data expands knowledge of the Pseudomonas PHO regulon, including species that are frequently used as bioinoculants, opening up the potential for more efficient and complete use of soil complexed P.
Project description:Pseudomonas aeruginosa, the type species of the Pseudomonas genus, is an environmental Gram negative bacterium, well-known for its ability to produce toxins, resist antibiotics, and opportunistically colonize various niches, including invertebrate and vertebrate hosts. P. aeruginosa produces redox active secondary metabolites called phenazines involved in quorum sensing, biofilm formation, virulence, and iron acquisition. Moreover, these colorful pigmented virulence factors act as ligands for the highly conserved aryl hydrocarbon receptor (AhR) thereby regulating antibacterial defenses in vertebrates. Pseudomonas spp. are some of the most frequently identified bacteria in larval and adult stages of wild mosquito populations. Here we investigated global transcriptional changes induced in A. coluzzii third instar larvae incubated with a sublethal concentration (50 µM) of 1-hydroxyphenazine (1-HP) or pyocyanin (Pyo) at 4 h and 8 h of continuous incubation by whole-genome DNA microarrays.
