Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle.

Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle.

Blog Article

Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections.Biofilms are Car Diffuser multicellular aggregates of cells enmeshed in an extracellular matrix.The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa.Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS.Mg(2+) limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS) production and biofilm formation.

Repression of retS expression under Mg(2+) limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl.We recently demonstrated that extracellular DNA sequesters Mg(2+) cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms.Here we show that exogenous DNA and EDTA, through their ability to chelate Mg(2+), promoted biofilm formation.The repression of retS in low Mg(2+) was directly controlled by PhoPQ.PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway.

In summary, Mg(2+) limitation is a biologically relevant environmental condition and Hair Loss Treatments the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P.aeruginosa biofilm formation.