S. rosetta - Algoriphagus model

We study a unique example of a eukaryotic-bacterial interaction in which diffusible signals from the prey bacteria Algoriphagus trigger the transition from single cells to colony development in the choanoflagellate Salpingoeca rosetta.

We previously discovered that a diffusible signal (Rosette Inducing Factor 1; RIF-1) from the prey bacterium Algoriphagus machipongonensis (Phylum Bacteroidetes) regulates multicellular development in S. rosetta. Through collaboration with Jon Clardy’s group (Harvard Medical School), we have identified and characterized the structure of the signaling molecule, which is a novel sulfonolipid.

Our goal is to elucidate the nature and function of the microbial signals that elicit morphogenic responses in choanoflagellates and how these signals impact the cell biology of other members of the microbial community.

Define the core circuit for sulfonolipid/sphingolipid metabolism in bacteria 

Sphingolipids are bioactive molecules that regulate cell growth, apoptosis, adhesion, cell migration and intracellular trafficking in diverse eukaryotes. In contrast, the endogenous functions of bacterial sphingolipids are unknown. Uncovering the pathway by which bacteria regulate morphogenesis in the choanoflagellates would simultaneously reveal new biological functions for this class of bacterial lipids and lay the foundation for investigating a previously unidentified class of interkingdom signaling molecules. 


Explore the mechanism of sulfonolipid/sphinoglipid signaling

The signaling potential and activity of diverse lipids is, in part, dependent upon their subcellular localization. Determining the mode by which RIF-1 is delivered from Algoriphagus cells will enable us to define the signaling interface in the Algoriphagus-S. rosetta relationship.  We hypothesize the mechanism of RIF-1 delivery through extruded bacterial membrane or by release of bacterial outer membrane vesicles. 

Presence of RIF-1 in Algoriphagus OMVs raises the possibility that other members of the microbial community in which Algoriphagus and choanoflagellates co-exist are affected. We also intend to explore more deeply the role of this metabolite in a variety of bacteria, animal and ecological contexts


Investigate impact of interkingdom signals on microbial community dynamics

The Algoriphagus-S. rosetta developmental interaction is uniquely suited to uncover fundamental mechanisms governing symbiotic systems dynamics of microbial communities and to test hypotheses about marine microbial ecology. We will establish continuous steady state culture systems under different nutrient regimes a to determine how external factors impact microbial communities.