RsmYZ regulated cooperation was induced by environmental nutrient factors.

<p>(A) Growth of WT PAO1 in M9<b> </b>minimal growth medium containing 1% adenosine (circle), 1% adenosine and 1% BSA as the dual carbon source (black square) and BSA was added after 40 hours cultivation (triangle). Expression of leadership and dependent genes of WT PAO1 were detected in M9<b> </b>minimal growth medium containing (B) 1% adenosine; (C) 0.5% adenosine+0.5% BSA; (D) 0.5% +0.5% BSA and the supernatants were removed every 4 hours; (E) 1% adenosine and then 1% BSA was added after 20 hours cultivation; (F) 1% adenosine and then 1% BSA was added after 40 hours cultivation. Data are means ± SEM, and representative of three experiments. *, <i>P</i><0.05; **, <i>P</i><0.01; ***, <i>P</i><0.001, one-way ANOVA (Tukey-Kramer post hoc).</p

Expression of <i>rsmY</i> and <i>rsmZ</i> was dramatically increased under stressful circumstances.

<p>Expression levels of genes were detected in WT PAO1, which was cultivated in (A) LB broth medium (B) MH-S cells as well as (C) LB broth medium containing 2<b> </b>µg/ml gentamicin at different time-points. Data are means ± SEM, and representative of three experiments. *, <i>P</i><0.05; **, <i>P</i><0.01, ***, <i>P</i><0.001, one-way ANOVA (Tukey-Kramer post hoc).</p

GacA-RsmYZ leadership cascade governs the initial expression of the QS-dependent genes.

<p>Gene expression of leadership and QS regulators in WT PAO1 (A) and QS-deficient strain PAO1-<i>ΔlasR</i> (B) in low density (OD₆₀₀≈0.12), quorum density (OD₆₀₀≈0.28), and high density (OD₆₀₀≈0.9) phases. Data are means ± standard error means (SEM), and representative of three experiments. *, <i>P</i><0.01; **, <i>P</i><0.001, one-way ANOVA (Tukey-Kramer post hoc).</p

High levels of <i>rsmY</i> and <i>rsmZ</i> expression could cause an enhanced biofilm production after 24 h.

<p>Production of biofilm was detected by crystal violet staining (A) and quantified at OD₅₉₅ (B). The data are represented as means ± SEM, six replicates per culture. *, <i>P</i><0.05, one-way ANOVA (Tukey-Kramer post hoc).</p

Cooperation activation was delayed due to the presence of <i>lasR</i> mutant.

<p>(A) The same amounts of wild type (WT) <i>P. aeruginosa</i> PAO1 were cultured in different volumes of LB broth medium. (B) 10<b> </b>µl of overnight cultivated WT PAO1, 5<b> </b>µl WT PAO1+5<b> </b>µl PAO1-<i>ΔlasR</i>, and 10<b> </b>µl PAO1-<i>ΔlasR</i> strains were independently cultured in the same volume of LB broth medium. Activation of cooperation (☆) was determined by significantly increased expression of <i>lasB</i> gene. Data are means ± SEM, and representative of three experiments. *, <i>P</i><0.05, one-way ANOVA (Tukey-Kramer post hoc).</p

Le Petit Marocain

31 août 19431943/08/31 (A31,N7918)-1943/08/31

Data_Sheet_1_Phenotypic heterogeneity unveils a negative correlation between antibiotic resistance and quorum sensing in Pseudomonas aeruginosa clinical isolates.PDF

Colonization of Pseudomonas aeruginosa in the lung environments frequently leads to the enrichment of strains displaying enhanced antibiotic resistance and reduced production of quorum-sensing (QS) controlled products. However, the relationship between the emergence of QS deficient variants and antibiotic resistance remains less understood. In this study, 67 P. aeruginosa strains were isolated from the lungs of 14 patients with chronic obstructive pulmonary disease, followed by determining their genetic relationship, QS-related phenotypes and resistance to commonly used antibiotics. The integrity of P. aeruginosa QS system was checked by DNA sequencing. The relationship between the QS system and antibiotic resistance was then assessed by correlation analyses. The function of the LasR protein and bacterial virulence were evaluated through homology modeling and nematode-infection assay. The influence of antibiotic on the development of extracellular protease production ability of P. aeruginosa was tested by an evolutionary experiment. The results showed that P. aeruginosa clinical strains displayed abundant diversity in phenotype and genotype. The production of extracellular proteases was significantly negatively correlated with antibiotic resistance. The strains with enhanced antibiotic resistance also showed a notable overlap with the mutation of lasR gene, which is the core regulatory gene of P. aeruginosa QS system. Molecular docking and Caenorhabditis elegans infection assays further suggested that P. aeruginosa with impaired LasR protein could also have varying pathogenicity. Moreover, in vitro evolution experiments demonstrated that antibiotic-mediated selective pressure, particularly from Levofloxacin contributed to the emergence of extracellular protease-negative strains. Therefore, this study provides evidence for the connection of P. aeruginosa QS system and antibiotic resistance, and holds significance for developing targeted strategies to address antibiotic resistance and improving the management of antibiotic-resistant infections in chronic respiratory diseases.</p