Morphology, ultrastructure, genomics, and phylogeny of Euplotes vanleeuwenhoeki sp. nov. and its ultra-reduced endosymbiont “Candidatus Pinguicoccus supinus” sp. nov

• Published in: Scientific reports Vol. 10; no. 1; p. 20311
• Main Authors: Serra, Valentina, Gammuto, Leandro, Nitla, Venkatamahesh, Castelli, Michele, Lanzoni, Olivia, Sassera, Davide, Bandi, Claudio, Sandeep, Bhagavatula Venkata, Verni, Franco, Modeo, Letizia, Petroni, Giulio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20-11-2020; Nature Publishing Group
• Subjects: 631/114; 631/114/2785; 631/114/739; 631/181; 631/181/2480; 631/181/735; 631/208; 631/208/182; 631/208/726; 631/326; 631/326/325; 631/326/41; Bioinformatics; Candidatus Pinguicoccus supinus; Computational Biology; DNA, Bacterial - isolation & purification; Euplotes - classification; Euplotes - genetics; Euplotes - microbiology; Euplotes - ultrastructure; Euplotes vanleeuwenhoeki; Genome, Bacterial; Genome, Mitochondrial; Genomes; Genomics; Humanities and Social Sciences; Microbiomes; Microorganisms; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Mitochondria; multidisciplinary; New species; Phylogeny; Science; Science (multidisciplinary); Symbionts; Symbiosis - genetics; Taxonomy; Terminology as Topic; Ultrastructure; Verrucomicrobia - genetics; Verrucomicrobia - isolation & purification
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-76348-z

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics and, more recently, on evolutionary relationships. With the birth of novel genomics/bioinformatics techniques and the increasing interest in microbiome studies, a further advance of taxonomic discipline appears not only possible but highly desirable. The present work proposes a new approach to modern taxonomy, consisting in the inclusion of novel descriptors in the organism characterization: (1) the presence of associated microorganisms (e.g.: symbionts, microbiome), (2) the mitochondrial genome of the host, (3) the symbiont genome. This approach aims to provide a deeper comprehension of the evolutionary/ecological dimensions of organisms since their very first description. Particularly interesting, are those complexes formed by the host plus associated microorganisms, that in the present study we refer to as “holobionts”. We illustrate this approach through the description of the ciliate
Euplotes vanleeuwenhoeki
sp. nov. and its bacterial endosymbiont “
Candidatus
Pinguicoccus supinus” gen. nov., sp. nov. The endosymbiont possesses an extremely reduced genome (~ 163 kbp); intriguingly, this suggests a high integration between host and symbiont.