Project 5: Functional and Evolutionary aspects of novel Rickettsia-related endosymbionts of eustigmatophyte algae

Based at the University of Ostrava in the Czech Republic, this project will build on our knowledge of eustigmatophytes and will aim to define the occurrence, evolution, biological and practical significance of newly discovered Rickettsia-related endosymbiotic bacteria in eustigmatophytes. The University of Ostrava has a strong background in research into Eustigmatophyceae and their phylogenetic diversity. One ongoing research project is exploring genomes and transcriptomes of four phylogenetically diverse eustigs with the aim of providing insights into several fundamental questions of eustig biology, genetics and evolution. One of the outcomes of this research is the discovery of novel putative symbionts or parasites of eustigmatophyte algae, provisionally denoted Candidatus phycorickettsia.

Tatiana Yurchenko has been appointed researcher for this project and, using a broad phylogenetic sampling of eustigmatophytes with molecular methods (PCR) and microscopy (FISH, TEM), and genomic and bioinformatic approaches, she will investigate:

  1. How common Phycorickettsia is in eusigmatophyte cultures and what is its intracellular localization
  2. What is the extent of genetic diversity within the Phycorickettsia group and to what extent do endosymbionts co-evolve with their algal hosts in a purely vertical manner rather than being disseminated horizontally
  3. What is the nature of the association between Phycorickettsia and eustigmatophytes – mutualistic or parasitic?

To address these questions, the following work will also be carried out:

  • Genomes of two Phycorickettsia lineages of different phylogenetic distance from the lineage recently sequenced in Eliáš’ lab will be sequenced and analyzed;
  • Growth characteristics of Phycorickettsia-infected and Phycorickettsia-free algal strains are being compared to establish possible impacts of Phycorickettsia on large-scale cultivation of eustigmatophytes; and
  • Complementary comparative analyses of the genomic data from the bacteria, coupled with transcriptomic data from the host algal cells, cultivation / axenisation experiments and metabolomic analyses (Jena / VIB), will be employed to find out whether these algal-bacterial associations are mutually beneficial and explore their physiological implications.

The aim of this research is to achieve a detailed understanding on the evolutionary origins and nature of the association between Candidatus Phycorickettsia and eustigmatophyte hosts, as well as practical knowledge for large-scale cultivation of eustigmatophyte algae in biotechnologies. Tatiana will collaborate with Ecofuel Laboratories, the Algoteca de Coimbra, VIB and the University of Jena as part of her research.