title: Species specificity of symbiosis and secondary metabolism in ascidians.
abstract: Ascidians contain abundant, diverse secondary metabolites, which are thought to serve a defensive role and which have been applied to drug discovery. It is known that bacteria in symbiosis with ascidians produce several of these metabolites, but very little is known about factors governing these 'chemical symbioses'. To examine this phenomenon across a wide geographical and species scale, we performed bacterial and chemical analyses of 32 different ascidians, mostly from the didemnid family from Florida, Southern California and a broad expanse of the tropical Pacific Ocean. Bacterial diversity analysis showed that ascidian microbiomes are highly diverse, and this diversity does not correlate with geographical location or latitude. Within a subset of species, ascidian microbiomes are also stable over time (R=-0.037, P-value=0.499). Ascidian microbiomes and metabolomes contain species-specific and location-specific components. Location-specific bacteria are found in low abundance in the ascidians and mostly represent strains that are widespread. Location-specific metabolites consist largely of lipids, which may reflect differences in water temperature. By contrast, species-specific bacteria are mostly abundant sequenced components of the microbiomes and include secondary metabolite producers as major components. Species-specific chemicals are dominated by secondary metabolites. Together with previous analyses that focused on single ascidian species or symbiont type, these results reveal fundamental properties of secondary metabolic symbiosis. Different ascidian species have established associations with many different bacterial symbionts, including those known to produce toxic chemicals. This implies a strong selection for this property and the independent origin of secondary metabolite-based associations in different ascidian species. The analysis here streamlines the connection of secondary metabolite to producing bacterium, enabling further biological and biotechnological studies.
authors.affiliation: Department of Medicinal Chemistry, L.S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT, USA.
authors.forename: Ma Diarey B
authors.initials: MD
authors.lastname: Tianero
authors.affiliation: 1] Department of Medicinal Chemistry, L.S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT, USA [2] School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Kwan
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Wyche
authors.affiliation: Study Design and Biostatistics Center, Division of Epidemiology, University of Utah, Salt Lake City, UT, USA.
authors.forename: Angela P
authors.initials: AP
authors.lastname: Presson
authors.affiliation: Department of Pharmacology and Toxicology, L.S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Koch
authors.affiliation: Department of Pharmacology and Toxicology, L.S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT, USA.
authors.forename: Louis R
authors.initials: LR
authors.lastname: Barrows
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Tim S
authors.initials: TS
authors.lastname: Bugni
authors.affiliation: Department of Medicinal Chemistry, L.S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT, USA.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Schmidt
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D044822:Biodiversity; D002140:California; D005431:Florida; D010140:Pacific Ocean; D064210:Secondary Metabolism; D013045:Species Specificity; D013559:Symbiosis; D014561:Urochordata / Q000382:microbiology* / Q000502:physiology