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Infections of Paramecium bursaria with bacteria and yeasts
Abstract:
Infections of Paramecium bursaria with bacteria and yeasts are reported. Bacteria and yeasts multiply in the algae-free ciliate and are transmitted at various conditions as are symbiotic chlorellae. Like chlorellae, the bacteria and the yeast cells are situated in perisymbiont vacuoles. Both bacteria and yeasts maintain their capability for independent existence and can be grown on standard nutrient agar. Infection experiments show that aposymbiotic P. bursaria can be infected with Chlorella, bacteria and yeast. Chlorella-bearing P. bursaria cannot be infected with bacteria or yeast. Bacteria-bearing paramecia can be infected with Chlorella but not with yeast. Yeast-bearing paramecia can be infected with Chlorella but not with bacteria. Following infections with Chlorella the paramecia lose their bacteria or yeast symbionts. The bacteria found in P. bursaria probably belong to the genus Pseudomonas; the yeast has been identified as Rodutorula rubra.
Insights
Paramecium bursaria can be infected by bacteria and yeast, but only when they lack symbiotic algae. Existing bacterial or yeast infections prevent new infections, highlighting microbial exclusivity in these ciliates.
Area of Science:
- Microbiology
- Protistology
- Symbiosis research
Background:
- Paramecium bursaria, a ciliate protozoan, is known to host symbiotic algae (Chlorella).
- The potential for P. bursaria to host other microorganisms, such as bacteria and yeasts, is less understood.
- Understanding microbial interactions within P. bursaria can reveal insights into host-symbiont dynamics.
Purpose of the Study:
- To investigate the susceptibility of Paramecium bursaria to infections by bacteria and yeasts.
- To determine the interactions between symbiotic Chlorella, bacteria, and yeasts within P. bursaria.
- To identify the specific bacterial and yeast species capable of infecting P. bursaria.
Main Methods:
- Infection experiments using aposymbiotic (algae-free) and symbiont-bearing P. bursaria with specific bacterial and yeast strains.
- Culturing of isolated bacteria and yeasts on standard nutrient agar to confirm viability.
- Microscopic observation to determine the location and presence of symbionts within the ciliates.
Main Results:
- Bacteria (likely Pseudomonas) and yeast (Rhodotorula rubra) can infect algae-free P. bursaria and establish perisymbiont vacuoles.
- P. bursaria already harboring Chlorella, bacteria, or yeast resist coinfection by other microbes.
- Infection with Chlorella leads to the expulsion of previously established bacterial or yeast symbionts.
Conclusions:
- Paramecium bursaria exhibits microbial exclusivity, with established symbionts preventing new infections.
- The presence of symbiotic Chlorella plays a crucial role in maintaining the exclusion of bacterial and yeast infections.
- This study identifies Pseudomonas and Rhodotorula rubra as potential bacterial and yeast symbionts of P. bursaria.