Table 1. Classification of abundant tunic OTUs.

OTU#	Isolate	RDP classification class/genus	Closest uncultured and cultured BLAST hits
			Acc. #		Source	Max. Id (%)
1*	CWH016	Flavobacteria/Arenibacter	DQ486485	Arenibacter sp. DG1238	Dinoflagellate	95
2*	—	Alphaprot./unclassified1	HQ326311 DQ167245	Uncultured clone SBS-RV-031 Kopriimonas byunsanensis KOPRI 13522	Biofilm Marine biofilm	99 88
3*	CWH001	Alphaprot./Kordiimonas	EU287361 GU289640	Uncultured bacterium clone S26–61 Kordiimonas sp. MEBiC06554	Arctic sediment Seawater	99 96
4	—	Alphaprot./unclassified2	HQ163356 JQ085424	Uncultured Alphaprot. SHZW738 alphaproteobacterium NH6–42	Seawater Seawater	92 85
8*	CWH003	Alphaprot./Kiloniella	EU287341 AB571945	Uncultured bacterium clone S26–41 Alphaproteobacterium AKA07–5	Arctic sediment −	99 96
10	—	Alphaprot./Breoghania	FJ543036 GQ272328	Uncultured Alphaprot. B07–10D Alphaproteobacterium UBF-P1	Earthworm gut Sand after oil spill	88 86
7*	CWH007	Flavobacteria/Muricauda	FJ203619 FJ348472	Uncultured bacterium clone SHFH709 Flavobacteriaceae bacterium A9	Coral Marine sponge	98 97
11	—	Gammaprot./Escherichia	KC002412 JX120100	Marine bacterioplankton clone P4-3B_16 Bacterium P618/	Seawater Swine feces	100 100
13	—	Alphaprot./unclassified3	JF297198 EF554909	Uncultured Hyphomicrobiaceae Devosia sp. G-He10	Lobster shell legion —	98 87

Abbreviations: OTU, operational taxonomic unit; RDP, Ribosomal Database Project; rRNA, ribosomal RNA.

Top BLAST hits and closest cultured BLAST hits for the nine OTUs with >1% of total 454 16 rRNA gene sequence abundance from tunicate samples. When available, almost complete 16S sequence was used for RDP classification and BLAST searches as indicated by an asterisk. BLAST search was performed on 18 January 2013.