P. bursaria is the only species of Paramecium that forms symbiotic relationships with algae, and it is often used in biology classrooms both as an example of a protozoan and also as an example of symbiosis.

[7] The PV can be distinguished from the digestive vacuole (DV) by the number and distribution of particles, exhibiting minimal endocytosis or exocytosis activity.

Moreover, the mechanism of the symbiotic relationship between Paramecium bursaria and Chlorella, based on comparative genome analysis, suggests that the host provides glutamine and magnesium.

In return, Chlorella within the perialgal vacuole (PV) provides the host with photosynthetic products such as fructose, maltose, and oxygen.

Andrew et al. (2016) developed a mathematical model, using the framework of general symbiotic relationships, to describe the mechanism of this interaction.

The host's growth rate is influenced by its nutritional state, which depends on the efficiency of nutrient exchange with the symbionts.

The results revealed five highly supported lineages corresponding to the syngens (R1–R5), which are genetically distinct but reproductively isolated among the P. bursaria strains sharing synapomorphic traits.