Aeration selects for mucoid phenotype of Pseudomonas aeruginosa

Krieg, D; Bass, Joseph A.; Mattingly, S J

doi:10.1128/jcm.24.6.986-990.1986

Cited by 38 publications

(16 citation statements)

References 29 publications

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“…Culture media. A modification of the chemically defined alginate-promoting (AP) medium of Mian et al (25), which has been described previously (17,18), was the primary growth medium used for the chemostat studies. The medium contained 100 mM monosodium glutamate, 100 mM sodium gluconate, 7.5 mM NaH2PO4, 16.3 mM K2HPO4, and 10 mM MgSO4 7H20.…”

Section: Methodsmentioning

confidence: 99%

Environmental conditions which influence mucoid conversion Pseudomonas aeruginosa PAO1

1991

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Growth and conversion to the mucoid phenotype by nonmucoid Pseudomonas aeruginosa PAO1 was studied in a chemostat system under conditions designed to reflect those likely to be present during chronic infection in the lung in cystic fibrosis patients. Mucoid variants were consistently isolated during continuous culture in the presence of 0.3 M NaCl or 5 or 10% glycerol. Mucoid subpopulations were also detected under conditions of carbon, nitrogen, or phosphate limitation. During carbon or nitrogen limitation, mucoid conversion was dependent upon the choice of substrate. Phosphate-limited cultures exhibited an inverse relationship between culture growth rate and number of mucoid organisms detected. Mucoid variants were not detected when dilution rates (D) exceeded 0.173 h-'. Conversely, at a D of 0.044 h-1, 40% of the population expressed the mucoid phenotype. Phosphorylcholine, a product of phosphojipase C activity on the major lung surfactant phosphatidylcholine, was also used as a growth substrate in nutrient limitation studies. Under all conditions, growth of PAO1 supplied with phosphorylcholine resulted in isolation of mucoid variants, indicating that the lung may provide at least one nutrient source conducive to mucoid conversion. Continuous culture also resulted in detection of a phage associated with strain PAO1. High titers of phage were present under all conditions, including those which yielded no mucoid organisms, suggesting that environmental conditions rather than the phage regulated the appearance of mucoid variants.Pseudomonas aeruginosa is responsible for much of the morbidity and mortality associated with chronic pulmonary infections in cystic fibrosis (CF) patients (10,15,24). With prolonged chronic infection, P. aeruginosa undergoes alteration from the classical nonmucoid form to an atypical mucoid form, which correlates with the production of the exopolysaccharide alginic acid (6). In the context of chronic lung infection, alginate is an important virulence determinant. The appearance of alginate-producing P. aeruginosa strains is usually associated with a poor patient prognosis (10). Alginate has been implicated in adherence to tracheal epithelium (21, 28) and has been associated with antiphagocytic function (29). While the relationship between mucoid P. aeruginosa and CF is well documented, the environmental factors of the CF lung responsible for conversion of nonmucoid P. aeruginosa to the alginate-producing mucoid form have yet to be defined.A chemostat model for the study of this organism under chronic diseaselike growth conditions (phosphate and nitrogen limitation) which would reflect the likely physiological status of organisms in the lungs of CF patients has recently been reported (18). In this study, phosphate-limited cultures of mucoid P. aeruginosa were capable of utilizing phosphorylcholine (PC), a product of phospholipase C activity on phosphatidylcholine (a major component of lung surfactant), as a sole source of phosphate for growth (18).In an effort to understand the environmen...

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Section: Methodsmentioning

confidence: 99%

Environmental conditions which influence mucoid conversion Pseudomonas aeruginosa PAO1

1991

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“…MEP lot 1 was prepared from organisms grown in deoxycholate citrate broth, a medium shown by Govan to stabilize MEP production (8). MEP lot 2 was obtained from the same strain cultured in modified Mian's medium, as described by Krieg et al (11). We employed one additional modification of this medium, which was to substitute Lglutamine for monosodium glutamate as the nitrogen source.…”

Section: Methodsmentioning

confidence: 99%

Immunogenic properties of Pseudomonas aeruginosa mucoid exopolysaccharide

1990

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Previous studies have shown that antibodies to Pseudomonas aeruginosa mucoid exopolysaccharide (MEP) can be divided into two types on the basis of their functional activity. One type is able to mediate opsonic killing in conjunction with leukocytes and complement, and the other type is not. We investigated, in mice, the properties of this antigen associated with elicitation of opsonic killing antibody. We found that smaller-sized material (KaV = 0.26), which has been tested as a human vaccine, elicited opsonic killing antibody in mice at low doses (1 to 10 ,ug) and at doses of .40 ,ug, only nonopsonic killing antibody was produced. A similar dose effect was seen with heat-killed mucoid P. aeruginosa cells. After immunization with high doses of this MEP or the heat-killed cells, the mice were refractory to induction of opsonic killing antibody no matter what dose of MEP was used as a booster. In contrast, a larger-molecular-weight preparation (Kav = 0.05) elicited opsonic killing antibody over a wide dose range (1 to 400 ,ug). Additionally, 50 ,ug of the larger-sized preparation could overcome the suppression induced by 50 ,ig of the smaller material. Suppression elicited by 50 ,ug of the smaller

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“…Together, our results demonstrated that sodium sulfate can suppress alginate production in mucoid P. aeruginosa strains. Environmental factors that influence bacterial growth, such as temperature (Leitao et al, 1992) and oxygen potential (Krieg et al, 1986), were reported to play roles in alginate production. We therefore explored whether suppressed alginate production is associated with altered bacterial growth by sodium sulfate.…”

Section: Resultsmentioning

confidence: 99%

Nonmucoid conversion of mucoidPseudomonas aeruginosainduced by sulfate-stimulated growth

Min¹,

Lee²,

Oh³

et al. 2014

FEMS Microbiol Lett

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Alginate-overproducing mucoid Pseudomonas aeruginosa, responsible for chronic airway infections in cystic fibrosis (CF) patients, is resistant to antibiotic treatments and host immune clearance. In this study, we performed a phenotype microarray screen and identified sulfate ion as a molecule that can suppress alginate production. When a mucoid P. aeruginosa strain CM21 and additional mucoid isolates were grown with 5% sodium sulfate, significantly decreased levels of alginate were produced. Suppression of alginate production was also induced by other sulfate salts. Expression of a reporter gene fused to the algD promoter was considerably decreased when grown with sulfate. Furthermore, bacterial cell shape was abnormally altered in CM21, but not in PAO1, a prototype nonmucoid strain, suggesting that sulfate-stimulated cell shape change is associated with transcriptional suppression of the alginate operon. Finally, a CM21 lpxC mutant defective in lipid A biosynthesis continued to produce alginate and maintained the correct cell shape when grown with sulfate. These results suggest a potential involvement of lipoploysaccharide biosynthesis in the sulfate-induced reversion to nonmucoid phenotype. This study proposes a novel strategy that can be potentially applied to treat persistent infection by recalcitrant mucoid P. aeruginosa.

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Aeration selects for mucoid phenotype of Pseudomonas aeruginosa

Cited by 38 publications

References 29 publications

Environmental conditions which influence mucoid conversion Pseudomonas aeruginosa PAO1

Environmental conditions which influence mucoid conversion Pseudomonas aeruginosa PAO1

Immunogenic properties of Pseudomonas aeruginosa mucoid exopolysaccharide

Nonmucoid conversion of mucoidPseudomonas aeruginosainduced by sulfate-stimulated growth

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