Free-living tubeworm endosymbionts found at deep-sea vents

Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138; Marine Biology, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria; Biology Department MS 9160, Western Washington University, 516 High Street, Bellingham, WA 98225

^* To whom correspondence should be addressed. Email: cavanaug{at}fas.harvard.edu.

	Abstract

Recent evidence suggests that deep-sea vestimentiferan tubeworms acquire their endosymbiotic bacteria from the environment each generation; thus free-living symbionts should exist. Here, free-living tubeworm symbiont phylotypes were detected in vent seawater and in biofilms at multiple deep-sea vent habitats by PCR amplification, DNA sequence analysis, and fluorescence in situ hybridization. These findings support environmental transmission as a means of symbiont acquisition for deep-sea tubeworms.