2 CLASSES OF METABOLITES FROM THEONELLA-SWINHOEI ARE LOCALIZED IN DISTINCT POPULATIONS OF BACTERIAL SYMBIONTS

The marine sponge Theonella swinhoei (lithistid Family Theonellidae, O rder Astrophorida) has yielded many important, bioactive natural produ cts, most of which share structural features with bacterial natural pr oducts. The presence of microbial symbionts in T. swinhoei has been re ported, and it was originally suggested that the cytotoxic macrolide s winholide A and many of the bioactive cyclic peptides from T. swinhoei were all produced by symbiotic cyanobacteria. By transmission electro n microscopy, we found four distinct cell populations to be consistent ly present in T. swinhoei: eukaryotic sponge cells, unicellular hetero trophic bacteria, unicellular cyanobacteria and filamentous heterotrop hic bacteria. Purification and chemical analyses of each cell type sho wed the macrolide swinholide A to be limited to the mixed population o f unicellular heterotrophic bacteria, and an anti-fungal cyclic peptid e occurred only in the filamentous heterotrophic bacteria. Contrary to prior speculation, no major metabolites were located in the cyanobact eria or sponge cells.