scholarly journals Pseudomonas aeruginosa PAO1 Pyocin Production Affects Population Dynamics within Mixed-Culture Biofilms

2008 ◽  
Vol 191 (4) ◽  
pp. 1349-1354 ◽  
Author(s):  
Richard D. Waite ◽  
Michael A. Curtis
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Population Dynamics ◽  
Mixed Culture ◽  
Bacterial Population ◽  
Anaerobic Conditions ◽  
Strain Pao1 ◽  
Pseudomonas Aeruginosa Pao1 ◽  
Sensitive Isolate ◽  
Slow Growing ◽  
Aerobic And Anaerobic

ABSTRACT Transcriptomic and phenotypic studies showed that pyocins are produced in Pseudomonas aeruginosa PAO1 aerobic and anaerobic biofilms. Pyocin activity was found to be high in slow-growing anaerobic biofilms but transient in aerobic biofilms. Biofilm coculture of strain PAO1 and a pyocin-sensitive isolate showed that pyocin production had a significant impact on bacterial population dynamics, particularly under anaerobic conditions.

scholarly journals Pseudomonas aeruginosa Regulatory Protein AnvM Controls Pathogenicity in Anaerobic Environments and Impacts Host Defense

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Yingchao Zhang ◽  
Chuan-min Zhou ◽  
Qinqin Pu ◽  
Qun Wu ◽  
Shirui Tan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Immune Response ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Anaerobic Conditions ◽  
Content Type ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT Pseudomonas aeruginosa, one of the most common pathogens in hospital-acquired infections, is tightly controlled by a multilayered regulatory network, including the quorum sensing system (QS), the type VI secretion system (T6SS), and resistance to host immunity. We found that the P. aeruginosa 3880 (PA3880) gene, which encodes an unknown protein, acts as a regulator of anaerobic metabolism in response to oxidative stress and virulence in P. aeruginosa. More than 30 PA3880 homologs were found in other bacterial genomes, indicating that PA3880 is widely distributed in the Bacteria kingdom as a highly conserved gene. Deletion of the PA3880 gene changed the expression levels of more than 700 genes, including a group of virulence genes, under both aerobic and anaerobic conditions. To further study the mechanisms of PA3880-mediated regulation in virulence, we utilized a bacterial two-hybrid assay and found that the PA3880 protein interacted directly with QS regulator MvfR and anaerobic regulator Anr. Loss of the PA3880 protein significantly blunted the pathogenicity of P. aeruginosa, resulting in increased host survival, decreased bacterial burdens, reduced inflammatory responses, and fewer lung injuries in challenged mice hosts. Mechanistically, we found that Cys44 was a critical site for the full function of PA3880 in influencing alveolar macrophage phagocytosis and bacterial clearance. We also found that AnvM directly interacted with host receptors Toll-like receptor 2 (TLR2) and TLR5, which might lead to activation of the host immune response. Hence, we gave the name AnvM (anaerobic and virulence modulator) to the PA3880 protein. This characterization of AnvM could help to uncover new targets and strategies to treat P. aeruginosa infections. IMPORTANCE Infections by Pseudomonas aeruginosa, one of the most frequently isolated human pathogens, can create huge financial burdens. However, knowledge of the molecular mechanisms involved in the pathogenesis of P. aeruginosa remains elusive. We identified AnvM as a novel regulator of virulence in P. aeruginosa. Deletion of anvM altered the expression levels of more than 700 genes under aerobic and anaerobic conditions, including quorum sensing system genes and oxidative stress resistance genes. AnvM directly interacted with MvfR and Anr, thus regulating their downstream genes. More importantly, AnvM directly bound to TLR2 and TLR5, which turn on the host immune response. These findings provide insights into the significance of AnvM homologs in pathogenic bacteria and suggest a potential drug target against bacterial infection.

Iron-binding compounds impair Pseudomonas aeruginosa biofilm formation, especially under anaerobic conditions

2009 ◽  
Vol 58 (6) ◽  
pp. 765-773 ◽  
Author(s):  
Che Y. O'May ◽  
Kevin Sanderson ◽  
Louise F. Roddam ◽  
Sylvia M. Kirov ◽  
David W. Reid
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Low Oxygen ◽  
Anaerobic Conditions ◽  
Chronic Infections ◽  
Strain Pao1 ◽  
Biofilm Inhibition ◽  
Oxygen Conditions ◽  
Biofilm Development ◽  
Chelating Compounds

The success of Pseudomonas aeruginosa in cystic fibrosis (CF) and other chronic infections is largely attributed to its ability to grow in antibiotic-resistant biofilm communities. This study investigated the effects of limiting iron levels as a strategy for preventing/disrupting P. aeruginosa biofilms. A range of synthetic and naturally occurring iron-chelating agents were examined. Biofilm development by P. aeruginosa strain PAO1 and CF sputum isolates from chronically infected individuals was significantly decreased by iron removal under aerobic atmospheres. CF strains formed poor biofilms under anaerobic conditions. Strain PAO1 was also tested under anaerobic conditions. Biofilm formation by this model strain was almost totally prevented by several of the chelators tested. The ability of synthetic chelators to impair biofilm formation could be reversed by iron addition to cultures, providing evidence that these effective chelating compounds functioned by directly reducing availability of iron to P. aeruginosa. In contrast, the biological chelator lactoferrin demonstrated enhanced anti-biofilm effects as iron supplementation increased. Hence biofilm inhibition by lactoferrin appeared to occur through more complex mechanisms to those of the synthetic chelators. Overall, our results demonstrate the importance of iron availability to biofilms and that iron chelators have potential as adjunct therapies for preventing biofilm development, especially under low oxygen conditions such as encountered in the chronically infected CF lung.

scholarly journals Quorum Sensing Negatively Controls Type III Secretion Regulon Expression in Pseudomonas aeruginosa PAO1

2005 ◽  
Vol 187 (11) ◽  
pp. 3898-3902 ◽  
Author(s):  
Sophie Bleves ◽  
Chantal Soscia ◽  
Patricia Nogueira-Orlandi ◽  
Andrée Lazdunski ◽  
Alain Filloux
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Type Iii Secretion ◽  
Down Regulation ◽  
Strain Pao1 ◽  
Systematic Analysis ◽  
Pseudomonas Aeruginosa Pao1 ◽  
Type Iii

ABSTRACT A systematic analysis of the type III secretion (T3S) genes of Pseudomonas aeruginosa strain PAO1 revealed that they are under quorum-sensing control. This observation was supported by the down-regulation of the T3S regulon in the presence of RhlR-C4HSL and the corresponding advanced secretion of ExoS in a rhlI mutant.

scholarly journals Bacterial Population Dynamics in Dairy Waste during Aerobic and Anaerobic Treatment and Subsequent Storage

2006 ◽  
Vol 73 (1) ◽  
pp. 193-202 ◽  
Author(s):  
Jeffery A. McGarvey ◽  
William G. Miller ◽  
Ruihong Zhang ◽  
Yanguo Ma ◽  
Frank Mitloehner
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Bacterial Population ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Rrna Gene ◽  
Aerobic Treatment ◽  
Dairy Waste ◽  
Subsequent Storage ◽  
Aerobic And Anaerobic

ABSTRACT The objective of this study was to model a typical dairy waste stream, monitor the chemical and bacterial population dynamics that occur during aerobic or anaerobic treatment and subsequent storage in a simulated lagoon, and compare them to those of waste held without treatment in a simulated lagoon. Both aerobic and anaerobic treatment methods followed by storage effectively reduced the levels of total solids (59 to 68%), biological oxygen demand (85 to 90%), and sulfate (56 to 65%), as well as aerobic (83 to 95%), anaerobic (80 to 90%), and coliform (>99%) bacteria. However, only aerobic treatment reduced the levels of ammonia, and anaerobic treatment was more effective at reducing total sulfur and sulfate. The bacterial population structure of waste before and after treatment was monitored using 16S rRNA gene sequence libraries. Both treatments had unique effects on the bacterial population structure of waste. Aerobic treatment resulted in the greatest change in the type of bacteria present, with the levels of eight out of nine phyla being significantly altered. The most notable differences were the >16-fold increase in the phylum Proteobacteria and the approximately 8-fold decrease in the phylum Firmicutes. Anaerobic treatment resulted in fewer alterations, but significant decreases in the phyla Actinobacteria and Bacteroidetes, and increases in the phyla Planctomycetes, Spirochetes, and TM7 were observed.

scholarly journals Antimicrobial Activity of Fosfomycin-Tobramycin Combination against Pseudomonas aeruginosa Isolates Assessed by Time-Kill Assays and Mutant Prevention Concentrations

2015 ◽  
Vol 59 (10) ◽  
pp. 6039-6045 ◽  
Author(s):  
María Díez-Aguilar ◽  
María Isabel Morosini ◽  
Ana P. Tedim ◽  
Irene Rodríguez ◽  
Zerrin Aktaş ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Mutant Selection ◽  
Content Type ◽  
Mutant Prevention Concentration ◽  
Fosfomycin Resistance ◽  
Time Kill ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTThe antibacterial activity of fosfomycin-tobramycin combination was studied by time-kill assay in eightPseudomonas aeruginosaclinical isolates belonging to the fosfomycin wild-type population (MIC = 64 μg/ml) but with different tobramycin susceptibilities (MIC range, 1 to 64 μg/ml). The mutant prevention concentration (MPC) and mutant selection window (MSW) were determined in five of these strains (tobramycin MIC range, 1 to 64 μg/ml) in aerobic and anaerobic conditions simulating environments that are present in biofilm-mediated infections. Fosfomycin-tobramycin was synergistic and bactericidal for the isolates with mutations in themexZrepressor gene, with a tobramycin MIC of 4 μg/ml. This effect was not observed in strains displaying tobramycin MICs of 1 to 2 μg/ml due to the strong bactericidal effect of tobramycin alone. Fosfomycin presented higher MPC values (range, 2,048 to >2,048 μg/ml) in aerobic and anaerobic conditions than did tobramycin (range, 16 to 256 μg/ml). Interestingly, the association rendered narrow or even null MSWs in the two conditions. However, for isolates with high-level tobramycin resistance that harbored aminoglycoside nucleotidyltransferases, time-kill assays showed no synergy, with wide MSWs in the two environments.glpTgene mutations responsible for fosfomycin resistance inP. aeruginosawere determined in fosfomycin-susceptible wild-type strains and mutant derivatives recovered from MPC studies. All mutant derivatives had changes in the GlpT amino acid sequence, which resulted in a truncated permease responsible for fosfomycin resistance. These results suggest that fosfomycin-tobramycin can be an alternative for infections due toP. aeruginosasince it has demonstrated synergistic and bactericidal activity in susceptible isolates and those with low-level tobramycin resistance. It also prevents the emergence of resistant mutants in either aerobic or anaerobic environments.

scholarly journals Quantitative correlation between susceptibility and OprJ production in NfxB mutants of Pseudomonas aeruginosa.

1996 ◽  
Vol 40 (4) ◽  
pp. 909-913 ◽  
Author(s):  
N Masuda ◽  
N Gotoh ◽  
S Ohya ◽  
T Nishino
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Parent Strain ◽  
Type A ◽  
Immunoblot Analysis ◽  
Type B ◽  
Wild Type ◽  
Strain Pao1 ◽  
Pseudomonas Aeruginosa Pao1 ◽  
Quantitative Correlation ◽  
Different Types

Various Pseudomonas aeruginosa PAO1 NfxB mutants were isolated on agar plates containing cefpirome and ofloxacin. They were classified into type A and type B, based on the degrees of changes in their susceptibilities. Type A mutants were four to eight times more resistant to ofloxacin, erythromycin, and new zwitterionic cephems, i.e., cefpirome, cefclidin, cefozopran, and cefoselis, than was the parent strain, PAO1. In contrast, type B mutants were more resistant to tetracycline and chloramphenicol, as well as ofloxacin, erythromycin, and the new zwitterionic cephems, than was PAO1, and they were four to eight times more susceptible to carbenicillin, sulbenicillin, imipenem, panipenem, biapenem, moxalactam, aztreonam, gentamicin, and kanamycin that was PAO1. The changes in susceptibilities of type B mutants were greater than those of type A mutants. The susceptibilities of both type A and type B mutants were restored to the level of PAO1 by transformation with plasmid pNF111, which contained the wild-type nfxB gene, demonstrating that they are NfxB mutants. Immunoblot analysis with a monoclonal antibody to OprJ revealed that type B mutants produced larger amounts of outer membrane protein OprJ than did type A mutants and that PAO1 produced an undetectable amount of it. Moreover, transconjugants obtained with the different types of NfxB mutants as the donor strains showed almost the same phenotypes as the corresponding donor strains. These results suggest that there are at least two nfxB mutations that show different phenotypes and that production of OprJ is associated with changes in susceptibilities of NfxB mutants.

scholarly journals Antibacterial Action of Nitric Oxide-Releasing Chitosan Oligosaccharides against Pseudomonas aeruginosa under Aerobic and Anaerobic Conditions

2015 ◽  
Vol 59 (10) ◽  
pp. 6506-6513 ◽  
Author(s):  
Katelyn P. Reighard ◽  
Mark H. Schoenfisch
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Anaerobic Conditions ◽  
No Donor ◽  
Bacterial Killing ◽  
Content Type ◽  
Bacterial Physiology ◽  
Chitosan Oligosaccharides ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTChitosan oligosaccharides were modified withN-diazeniumdiolates to yield biocompatible nitric oxide (NO) donor scaffolds. The minimum bactericidal concentrations and MICs of the NO donors againstPseudomonas aeruginosawere compared under aerobic and anaerobic conditions. Differential antibacterial activities were primarily the result of NO scavenging by oxygen under aerobic environments and not changes in bacterial physiology. Bacterial killing was also tested against nonmucoid and mucoid biofilms and compared to that of tobramycin. Smaller NO payloads were required to eradicateP. aeruginosabiofilms under anaerobic versus aerobic conditions. Under oxygen-free environments, the NO treatment was 10-fold more effective at killing biofilms than tobramycin. These results demonstrate the potential utility of NO-releasing chitosan oligosaccharides under both aerobic and anaerobic environments.

scholarly journals Impairment of Pseudomonas aeruginosa Biofilm Resistance to Antibiotics by Combining the Drugs with a New Quorum-Sensing Inhibitor

2015 ◽  
Vol 60 (3) ◽  
pp. 1676-1686 ◽  
Author(s):  
Aurelie Furiga ◽  
Barbora Lajoie ◽  
Salome El Hage ◽  
Genevieve Baziard ◽  
Christine Roques
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Homoserine Lactone ◽  
Regulatory Genes ◽  
Antibiofilm Activity ◽  
Anaerobic Conditions ◽  
Content Type ◽  
Biofilm Development ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Pseudomonas aeruginosaplays an important role in chronic lung infections among patients with cystic fibrosis (CF) through its ability to form antibiotic-resistant biofilms. InP. aeruginosa, biofilm development and the production of several virulence factors are mainly regulated by therhlandlasquorum-sensing (QS) systems, which are controlled by twoN-acyl-homoserine lactone signal molecules. In a previous study, we discovered an original QS inhibitor,N-(2-pyrimidyl)butanamide, called C11, based on the structure of C4-homoserine lactone, and found that it is able to significantly inhibitP. aeruginosabiofilm formation. However, recent data indicate thatP. aeruginosagrows under anaerobic conditions and forms biofilms in the lungs of CF patients that are denser and more robust than those formed under aerobic conditions. Our confocal microscopy observations ofP. aeruginosabiofilms developed under aerobic and anaerobic conditions confirmed that the biofilms formed under these two conditions have radically different architectures. C11 showed significant dose-dependent antibiofilm activity on biofilms grown under both aerobic and anaerobic conditions, with a greater inhibitory effect being seen under conditions of anaerobiosis. Gene expression analyses performed by quantitative reverse transcriptase PCR showed that C11 led to the significant downregulation ofrhlQS regulatory genes but also to the downregulation of bothlasQS regulatory genes and QS system-regulated virulence genes,rhlAandlasB. Furthermore, the activity of C11 in combination with antibiotics againstP. aeruginosabiofilms was tested, and synergistic antibiofilm activity between C11 and ciprofloxacin, tobramycin, and colistin was obtained under both aerobic and anaerobic conditions. This study demonstrates that C11 may increase the efficacy of treatments forP. aeruginosainfections by increasing the susceptibility of biofilms to antibiotics and by attenuating the pathogenicity of the bacterium.

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