Influence of iron-limited continuous culture on physiology and virulence of Legionella pneumophila
| Autor: | R B Fitzgeorge, Brian William James, C. W. Keevil, W S Mauchline, P J Dennis |
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| Rok vydání: | 1995 |
| Předmět: |
Aerosols
biology Strain (chemistry) Iron Guinea Pigs Immunology Virulence biology.organism_classification Microbiology Legionella pneumophila Culture Media Ferrous Chemically defined medium chemistry.chemical_compound Infectious Diseases chemistry Animals Parasitology Legionnaires' Disease Legionella pneumophila Serogroup 1 Bacteria Research Article Hemin |
| Zdroj: | Infection and Immunity. 63:4224-4230 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.63.11.4224-4230.1995 |
| Popis: | A virulent strain of Legionella pneumophila serogroup 1, subgroup Pontiac, was grown in continuous culture at a constant growth rate under iron-replete and iron-limited conditions. Iron limitation was achieved by the removal of ferrous sulfate and hemin from the chemically defined medium. Residual contaminating iron, 0.45 microM, was sufficient to support iron-limited growth. Typical iron-replete cultures metabolized 3.3 microM iron. Serine provided the principal source of carbon and energy for both cultures, although iron-replete cultures also depleted a number of other amino acids. There was a 40% decrease in culture biomass under iron-restricted conditions. Iron limitation did not significantly affect carbohydrate metabolism, with the molar growth yield for carbon (Ycarbon) comparable for both cultures. However, under iron-limited conditions a sixfold increase in Yiron correlated with a significant decrease in the iron content of the biomass, as the culture utilized the available iron more efficiently. Highly pleomorphic iron-replete cultures became uniform cultures of short fine rods when adapted to iron-deficient conditions. In addition to the morphological and physiological changes, iron limitation had a critical effect on culture virulence. The virulence of this strain was significantly (P < 0.05) reduced when the culture was subjected to iron-limited conditions. This phenomenon was reversible, with a significant increase in culture virulence upon reversion to iron-replete conditions. When compared in an in vitro macrophage assay, the number of culturable avirulent iron-limited cells located intracellularly after infection was significantly lower than for the virulent replete and control cultures. These results further support the role of environmental parameters in regulating the virulence of L. pneumophila. |
| Databáze: | OpenAIRE |
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