Photobiont Flexibility in <i>Paramecium bursaria</i>: Double and Triple Photobiont Co-Habitation

Abstract

The green ciliate, Paramecium bursaria, has evolved a mutualistic relationship with endosymbiotic green algae (photobionts). Under culture conditions, photobionts are usually unified (to be single species) within each P. bursaria strain. In most cases, the algal partners are restricted to either Chlorella variabilis or Micractinium reisseri (Chlorellaceae, Trebouxiophyceae). Both species are characterized by particular physiology and atypical group I intron insertions, although they are morphologically indistinguishable from each other or from other Chlorella-related species. Both algae are exclusive species that are viable only within P. bursaria cells, and therefore their symbiotic relationship can be considered persistent. In a few cases, the other algal species have been reported as P. bursaria photobionts. Namely, P. bursaria have occasionally replaced their photobiont partner. This paper introduces some P. bursaria strains that maintain more than one species of algae for a long period. This situation prompts speculations about flexibility of host-photobiont relationships, how P. bursaria replaced these photobionts, and the infection theory of the group I introns.

Algal Diversity in Paramecium bursaria: Species Identification, Detection of Choricystis parasitica, and Assessment of the Interaction Specificity

“…parasitica as potential endosymbiont of P. bursaria. In previous observations the co-occuring primary symbiont was identified as Chlorella [31,40].…”

Increasing the extraction efficiency of algal lipid for biodiesel production: Novel application of algal viruses

“…The microalgal species was confirmed by partial sequence of 18S rRNA of microalgae using outsourcing the sequencing services to Macrogen Inc. Seoul, South Korea. The sequencing was performed using the primers and conditions as prescribed by Hoshina and Fujiwara (2012). The partial nucleotide sequence was subjected to Basic Local Alignment Search Tool (BLAST) (Altschul et al, 1990).…”