Microbial symbiosis between Francisella-like bacteria and cold-adapted marine ciliates living in polar regions
Symbioses, the close and long-lasting associations between different organisms, are widespread between animals and between animals and microorganisms. Like their multicellular descendants, unicellular eukaryotes also host a large variety of endosymbiotic bacteria and represent interesting biological systems for investigating the formation and evolution of microbial symbioses. From species of marine ciliates with bipolar (Arctic and Antarctic) distribution, we have isolated gamma-proteobacteria related to Francisella, a genus that includes pathogenic species of fish and humans (the best known is F. tularensis, the causative agent of tularemia). These endosymbionts have been identified as candidates for a new genus and a new species, named 'Parafrancisella adeliensis' with reference to Adelie Cove (the site in Terra Nova Bay from which the host ciliate strain comes). Analysis of the P. adeliensis genome revealed that it contains, in the so-called 'Francisella Pathogenicity Island', genes encoding a type VI secretion system required to colonize and multiply into the host. P. adeliensis is non-pathogenic and easy to maintain in the laboratory, therefore the Euplotes/Parafrancisella microbial association can be used to investigate the role of secreted proteins on host fitness and the mechanism of bacterial invasion of eukaryotic cells.
Keywords - ENGLISH
Microbial symbiosis, microbial interactions, microbial ecology, ciliates, polar biology, Francisella
6. Graphical abstract/representative picture (1000x600 pixels,
Active participants in the research line (PI last author or *)
Laura Giusti; Dezemona Petrelli; Adriana Vallesi
External Collaborations
Graziano Di Giuseppe (Università di Pisa); Andreas Sjödin (Swedish Defence Research Agency, FOI, Sweden); Eduardo Villalobo (Universidad de Sevilla, Spain)
Pillar
Environmental Sustainability
Macroareas in Environmental Sustainability
Environmental Microbiology and Molecular Ecology
Email Address
adriana.vallesi@unicam.it
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