New Intranuclear Symbiotic Bacteria from Macronucleus of Paramecium putrinum—“Candidatus Gortzia Yakutica”

Holospora-like bacteria (HLB) are obligate intracellular Alphaproteobacteria, inhabiting nuclei of Paramecium and other ciliates such as “Candidatus Hafkinia” is in Frontonia. The HLB clade is comprised of four genera, Holospora, Preeria, “Candidatus Gortzia”, and “Candidatus Hafkinia”. These bacteria have a peculiar life cycle with two morphological forms and some degree of specificity to the host species and the type of nucleus they inhabit. Here we describe a novel species of HLB—“Candidatus Gortzia yakutica” sp. nov.—a symbiont from the macronucleus of Paramecium putrinum, the first described HLB for this Paramecium species. The new endosymbiont shows morphological similarities with other HLB. The phylogenetic analysis of the SSU rRNA gene places it into the “Candidatus Gortzia” clade.