Related Experiment Videos
Pleomorphism of Legionella pneumophila
Abstract:
Legionella pneumophila (Lp), serogroups 1-6, was grown in vitro on a variety of media, in embryonated hens' eggs, and in guinea pigs. The morphology of the microbe was examined by light, immunofluorescent, and electron microscopy (transmission, scanning, negative staining). The configuration of all serogroups examined differed somewhat on agar media, in liquid media, and in vivo. Each serogroup of Lp showed pleomorphic features indistinguishable from the others. Except for filamentous forms, pleomorphism was least conspicuous on agar. By contrast, pleomorphism was most apparent in yeast extract broth, and it was detected by all of the morphologic techniques employed. Bacilli were seen most commonly, but the spectrum of forms was as follows: cocci, coccobacilli (short bacilli), medium bacilli, bacilli with terminal cocci, filamentous forms, and branches. Diplococci, branches, and stalks were only rarely seen, and the latter form was never visualized by immunofluorescence. In tissue samples from infected guinea pigs and embryonated hens' eggs, Lp was typically a short bacillus, but coccoid and coccobacillary forms were seen. Lp is clearly a pleomorphic bacterium, particularly when grown in yeast extract broth. The variety of forms described herein might provide clues to taxonomy, ecologic niche, and physiology of Lp.
Insights
Legionella pneumophila (Lp) exhibits significant pleomorphism, displaying various forms like cocci and bacilli across different growth conditions. Understanding this bacterial pleomorphism is key to its taxonomy and physiology.
Area of Science:
- Microbiology
- Bacterial Morphology
Background:
- Legionella pneumophila (Lp) is a significant human pathogen.
- Understanding bacterial morphology is crucial for taxonomy and understanding pathogen behavior.
Purpose of the Study:
- To investigate the pleomorphism of Legionella pneumophila (Lp) across different growth environments.
- To characterize the diverse morphological forms of Lp using various microscopy techniques.
Main Methods:
- Cultivation of Lp serogroups 1-6 in vitro (agar, liquid media) and in vivo (hens' eggs, guinea pigs).
- Morphological examination using light, immunofluorescent, and electron microscopy (TEM, SEM, negative staining).
Main Results:
- Lp displayed pleomorphic features, with morphology varying by growth medium and environment.
- Yeast extract broth revealed the most pronounced pleomorphism, including cocci, coccobacilli, bacilli, and filamentous forms.
- In vivo, Lp typically appeared as short bacilli, but coccoid and coccobacillary forms were also observed.
Conclusions:
- Legionella pneumophila is a highly pleomorphic bacterium, especially in yeast extract broth.
- The observed pleomorphism may offer insights into Lp's taxonomy, ecological niche, and physiology.