'Candidatus Megaira' are diverse symbionts of algae and ciliates with the potential for defensive symbiosis

• DOI: 10.1099/mgen.0.000950
• Publication Date: 2023-03-16T13:19:08Z
• Authors: Helen Rebecca Dav...; Gregory D. D. Hurst; Stefanos Siozios
• Keywords: Candidatus; Phylogenomics; Endosymbiosis; Obligate

Symbiotic microbes from the genus 'Candidatus Megaira' ( Rickettsiales ) are known to be common associates of algae and ciliates. However, genomic resources for these bacteria scarce, limiting our understanding their diversity biology. We therefore utilize Sequence Read Archive metagenomic assemblies explore this genus. successfully extract four draft ' Ca . genomes including one complete scaffold a Megaira identify an additional 14 uncategorized environmental metagenome-assembled genomes. use information resolve phylogeny hyper-diverse Megaira', with hosts broadly spanning ciliates, micro- macro-algae, find that current single designation significantly underestimates diversity. also evaluate metabolic potential ''Ca new data no clear evidence nutritional symbiosis. In contrast, we hypothesize defensive symbiosis in 'Ca Intriguingly, symbiont genome revealed proliferation ORFs ankyrin, tetratricopeptide leucine-rich repeats such as those observed Wolbachia where they considered important host–symbiont protein–protein interactions. Onward research should investigate phenotypic interactions between various hosts, economically Nemacystus decipiens , target acquisition reflect massively variable group.