Table 1.

Affiliation and closest relatives in Genbank to the enriched (>1% difference in mean proportions) 16S rRNA gene OTUs in bulk particle samples (D1–D7) compared to seawater samples (0.2–10 and 0.2–3 µm)

OTU ID	Class affiliation	Closest relative	Similarity	Accession number
Enriched in bulk particle samples
OTU_43683	Alphaproteobacteria	Shimia sp.	100%	KT720466.1
OTU_20532	Alphaproteobacteria	Tropicibacter multivorans	100%	KP843700.1
OTU_16894	Chloroplast	Rhizosolenia	97%	KJ958482.1
OTU_25878	Flavobacteriia	Unclassified Bacteroidetes; Flavobacteriales
OTU_4074	Gammaproteobacteria	Alteromonas sp.	100%	KX356439.1
OTU_26436	Gammaproteobacteria	Pseudoalteromonas sp.	100%	KX806641.1
OTU_22018	Gammaproteobacteria	Unclassified Gammaproteobacteria; Oceanospirillales
OTU_29878	Gammaproteobacteria	Thalassolituus oleivorans	97%	KF170318.1
OTU_18280	Gammaproteobacteria	Photobacterium angustum	100%	KC534344.1
OTU_44280	Opitutae	Uncultured Verrucomicrobia; Puniceicoccaceae	99%	HQ675288.1
OTU_8705	Saprospirae	Unclassified Bacteroidetes; Saprospiraceae
Enriched in free-living seawater samples
OTU_19700	Acidimicrobiia	Uncultured Actinobacteria	100%	HQ675198.1
OTU_36708	Alphaproteobacteria	Pelagibacteraceae	100%	HQ675347.1
OTU_39648	Alphaproteobacteria	Pelagibacter sp.	100%	LN850157
OTU_30217	Alphaproteobacteria	Pelagibacteraceae	99%	JF488446.1
OTU_817	Alphaproteobacteria	Uncultured Alphaproteobacteria	97%	JF488548.1
OTU_18321	Alphaproteobacteria	Pelagibacteraceae	99%	HQ675689.1
OTU_26273	Deltaproteobacteria	Uncultured Deltaproteobacteria; Sva0853	99%	U65908.1
OTU_6835	Deltaproteobacteria	Uncultured Deltaproteobacteria; Sva0853	100%	HQ675271.1
OTU_31137	SAR202	Unclassified Chloroflexi
OTU_15929	AB16	Uncultured SAR406	96%	JF488613.1
OTU_23515	Synechococcophycideae	Prochlorococcus	100%	CP007753.1
OTU_23585	Synechococcophycideae	Synechococcus sp.	100%	JF306716.1