No abstract

Legionellales-infected water is a frequent cause of local outbreaks of Legionnaires’ disease and Pontiac fever. Decontaminations are difficult because Legionellales reproduce in eukaryotic microorganisms (protists). Most often, Legionellales have been isolated from amoebae; however, the culture-based sampling methods are taxonomically biased. Sequencing studies show that amoebae in the cercozoan class Thecofilosea are dominant in soils and wastewater treatment plants, prompting us to screen their capability to serve as potential hosts of endosymbiotic bacteria. Environmental isolates of Thecofilosea contained a surprising richness of endosymbiotic Legionellales, including Legionella. Considering the widespread dispersal of Legionellales in apparently unrelated amoeboid protist taxa, it appears that the morphotype and not the evolutionary origin of amoebae determines their suitability as hosts for Legionellales. We further provide a protocol for gnotobiotic cultivation of Legionellales and their respective hosts, facilitating future genomic and transcriptomic research of host–symbiont relationships.

Finding a partner and having sex to produce babies is a common way to reproduce. Yet, upon closer look, we see that nature provides many ways for reproduction. What about a world without males? What first sounds impossible is the reality for many organisms that reproduce asexually, meaning without having sex. Females produce daughters that are clones of themselves, so no partner is required and males are dispensable. An Example of such all-female societies are several species of oribatid mites, which live in soils. These mites were already on earth long before the dinosaurs. Have oribatid mites always been asexual? Why do they reproduce without males? Does asexual reproduction have any advantages? Keep reading to learn about asexual reproduction and why oribatid mites are a key organism to investigate the question, “Why sex?”.