Physiology and morphology of Legionella pneumophila in continuous culture at low oxygen concentration

Mauchline, W. S., Araujo, R., Wait, R., Dowsett, A. B., Dennis, P. J. and Keevil, C. W. (1992) Physiology and morphology of Legionella pneumophila in continuous culture at low oxygen concentration. Journal of General Microbiology, 138 (11), 2371-2380. (doi:10.1099/00221287-138-11-2371).

Abstract

Two strains of Legionella pneumophila serogroup 1 monoclonal subgroup Pontiac were grown for the first time in continuous culture using a chemically defined medium. The influence of temperature on physiology and morphology was investigated by fixing the growth rate (equal to the dilution rate, D) at 0-08 h^-1 and controlling the pH and dissolved oxygen concentration of the culture. Serine provided the principal source of carbon and energy but growth was limited by tyrosine. The bacterium behaved as a microaerophile in this medium, with maximal growth occurring at 0-31 (mg O₂)1^-1 (equivalent to a dissolved oxygen tension of 4% (v/v) air saturation at 30°C). The cultures consisted of flagellated, short rods at 24°C, but exhibited an increased level of pleomorphism and the loss of flagella as the temperature was increased to 37°C. The presence of intracellular granules was noted, and their abundance was temperature-dependent. Polyhydroxybutyrate was present in L. pneumophila, and the proportion of the cell dry weight that it accounted for varied with temperature, being maximal at 24°C. The ratio of saturated to unsaturated fatty acids in the cells decreased as the temperature was reduced towards 24°C. so as to maintain membrane fluidity at low growth temperature.

This record has no associated files available for download.

Contributors

Author: C. W. Keevil

Download statistics