THE EFFECT OF A PHOTOSYNTHETIC SYMBIONT ON THE SPONGE MICROBIOME

The marine sponge Petrosia ficiformis hosts a diverse assemblage of bacteria, including, in illuminated sites, the photosynthetic endocellular Candidatus Synechococcus feldmanni, which exhibit a facultative symbiotic association with this sponge. The facultative nature of the association with Ca. s. feldmanni is shown by transplant experiments: cyanobacteria-harboring specimens transplanted to dark environments (underwater caves) lost the cyanobacterial symbionts, and cyanobacteria-free specimens transplanted out of the dark caves acquired cyanobacterial symbionts after eight months from transplantation. In the current study we examined the microbiome structure of P. ficiformis specimens in three geographic locations (Spain, Italy and Israel), and for two locations we also compared the microbiome community in specimens that either harbor or not the cyanobacterial symbionts. In current ongoing work we are also analyzing potential shifts in the microbiome as a response to sponge transplants (break-down of symbiosis with the cyanobacteria and acquisition of the cyanobacteria). Further, we plan to investigate the active microbiome in the different symbiotic states (with and without photosynthetic symbiont), using 16S amplicon sequencing on cDNA.