Pseudomonas aeruginosa est un pathogene opportuniste induisant des infections chroniques chez les patients atteints de mucoviscidose. L'eradication de ces infections est presque impossible a l'âge adulte du fait de la formation de biofilms dans les poumons des patients. Les traitements antibiotiques actuels sont peu efficaces contre les biofilms car ce mode de vie assure d'une part la protection des bacteries contre les agents anti-microbiens par l'intermediaire de la matrice extracellulaire, et favorise d'autre part l'emergence de mecanismes de resistance. Il est donc essentiel de trouver des alternatives therapeutiques. La bacterie marine Pseudoalteromonas sp. 3J6 secrete une molecule a activite anti-biofilm efficace contre la souche de laboratoire P. aeruginosa PA01 et les souches cliniques P. aeruginosa MUC-N1, MUC-N2 et MUC-P4. Ces souches ont ete caracterisees aux niveaux de leur formation de biofilms in vitro et de leur virulence . Ceci a montre que ces souches sont tres differentes les unes des autres et qu'une seule souche, telle que la souche de laboratoire PA01, ne peut pas etre representative des profils observes. Il est donc necessaire de mener les etudes anti-biofilms sur plusieurs souches, telles que celles que nous avons selectionnees. Le potentiel therapeutique du surnageant de culture (SNa.Js} de Pseudoalteromonas sp. 3J6 et son extrait (Ea.Js} a ete etudie en evaluant leur toxicite, la reponse inflammatoire, leur impact sur la production de facteurs de virulence et leur potentiel therapeutique . SNa.Js et Ea.Js n'etaient pas toxiques vis-a-vis des modeles testes, n'induisaient pas de reponse inflammatoire dans les poumons de souris et n'augmentaient pas la production par P. aeruginosa des facteurs de virulence quantifies. De plus, SNa.Js s'est avere etre aussi efficace que l'antibiotique ciprofloxacine pour traiter une infection a P. aeruginosa MUC-N2 in vivo sur modele murin. Ces resultats sont encourageants quant a un potentiel therapeutique de la molecule a activite anti-biofilm pour contribuer au traitement des infections a P. aeruginosa chez les patients atteints de mucoviscidose.
To simultaneously obtain proteome data of host and pathogen from an internalization experiment, human alveolar epithelial A549 cells were infected with Staphylococcus aureus HG001 which carried a plasmid (pMV158GFP) encoding a continuously expressed green fluorescent protein (GFP). Samples were taken hourly between 1.5 h and 6.5 h post infection. By fluorescence activated cell sorting GFP-expressing bacteria could be enriched from host cell debris, but also infected host cells could be separated from those which did not carry bacteria after contact (exposed). Additionally, proteome data of A549 cells which were not exposed to S. aureus but underwent the same sample processing steps are provided as a control. Time-resolved changes in bacterial protein abundance were quantified in a label-free approach. Proteome adaptations of host cells were monitored by comparative analysis to a stable isotope labeled cell culture (SILAC) standard. Proteins were extracted from the cells, digested proteolytically, measured by nanoLC-MS/MS, and subsequently identified by database search and then quantified. The data presented here are related to a previously published research article describing the interplay of S. aureus HG001 and human epithelial cells (Surmann et al., 2015 [1]). They have been deposited to the ProteomeXchange platform with the identifiers PRIDE: http://www.ebi.ac.uk/pride/archive/projects/PXD002384 for the S. aureus HG001 proteome dataset and PRIDE: http://www.ebi.ac.uk/pride/archive/projects/PXD002388 for the A549 proteome dataset.
Volume 86, no. 20, e00893-20, 2020, https://doi.org/10.1128/AEM.00893-20. This article was published on 1 October 2020 with improper formatting for affiliation “c.” This has been corrected in the version of the article posted on 5 October 2020.
Biofilms produced by Pseudomonas aeruginosa present a serious threat to cystic fibrosis patients. Here, we report the draft genome sequences of four cystic fibrosis isolates displaying various mucoid and biofilm phenotypes. The estimated average genome size was about 6,255,986 ± 50,202 bp with a mean G+C content of 66.52 ± 0.06%.
Pseudomonas aeruginosa biofilm formation was increased by addition of sucrose to Luria-Bertani medium, whereas addition of NaCl to a final similar osmolarity and use of maltose instead of sucrose, were ineffective. In a previous study, we showed that the extracytoplasmic sigma factor SigX is activated in the presence of sucrose. The sucrose-mediated pellicle increase was abolished in a sigX mutant strain. Sucrose addition led to an increase in pel expression and cyclic-diguanylate (c-di-GMP) pool level production. Interestingly, these two phenotypes were strongly decreased in a sigX mutant. Since pel is not known as a SigX-target, we suspect SigX to be involved in the c-di-GMP production. We found that expression of the diguanylate cyclase PA4843 gene was increased in the presence of sucrose at least partly through SigX activity. Our study shows that sucrose itself rather than osmolarity favours the biofilm mode of P. aeruginosa through the activation of SigX.
Five out of a number of Bacillus cereus strains isolated from soil produced high titre specific bacteriocin (megacin A) in mitomycin C-induced cultures. In the course of cultivation with ethidium bromide, the strains gave off segregants not producing bacteriocin (cin-). The lysate of two wild strains formed plaques on the corresponding cin- bacteria. The two phages (wx23 and wx26) were identical in antigenic structure with phage wx was present in the lysate of B. cereus strain W, and converted cin- derivatives into cultures producing megacin A (phospholipase A). The phages produced plaques at 26 degrees C but not at 37 degrees C. In the lysates of the remaining three strains phages were not detected with biological and morphological methods; these cultures have been assumed to carry defective prophage genome. As the corresponding prophages are responsible for the determination of inducible phospholipase A production, phages named wx seem to form a separate group of B. cereus phages.
