Speaker
Description
Endosymbioses can give rise to new combinations of biochemical capabilities that promote evolutionary innovation and diversification. But despite the many examples of known endosymbioses across the tree of life, their de novo emergence is rare and challenging to uncover in retrospect. Using fluidic force microscopy (FluidFM), we directly implant bacteria into the filamentous fungus Rhizopus microsporus to follow the fate of artificially induced endosymbioses. While Escherichia coli implanted into the cytosol induced septum formation, effectively halting endosymbiogenesis, Mycetohabitans rhizoxinica was transmitted vertically to the progeny at low frequency. Continuous positive selection on endosymbiosis through cell sorting mitigated initial fitness constraints by several orders of magnitude upon adaptive evolution. These phenotypic changes were underscored by the accumulation of mutations in the host as the system stabilized. In the new host, the bacterium produced rhizoxin congeners, demonstrating the transfer of a metabolic function through induced endosymbiosis. Single cell implantation thus provides a powerful experimental approach to study critical events at the onset of endosymbiogenesis, highlights associated costs and opportunities, and opens possibilities for synthetic approaches towards designing endosymbioses with desired traits.
