Table 1.

Transmission of bacteria in the coral microbiome transplantation experiments. A subset of the 112 transmitted bacterial candidates is shown for Pocillopora sp. This subset consists of amplicon sequence variants (ASVs) within the most abundant bacterial orders that contain >200 reads. For Porites sp., all 16 transmitted bacterial variants are shown. Bacterial orders [and families] are listed together with the number of ASVs within these taxonomic groups and their relative abundances within the “I” recipient microbiome community. For each bacterial order, up to three most abundant ASVs are listed with their lowest taxonomic classification (SILVA v 132) and nearest relative information from GenBank (NCBI)

Pocillopora “I” recipient microbiomes
Order [families]	Relative abundance	No. of ASVs	Lowest taxonomic classification (SILVA) | sources and nearest relatives [% similarity; GenBank accession#]
Dstr-E11 [unclassified]	3.73	1	Unclassified Dstr-E11 | Montastraea franksi (coral) [99.75%; GU118824.1], Diploria strigosa (coral) [99.75%; GU118205.1]
Bacteria [unclassified]  Rhodobacterales [Rhodobacteraceae]	3.57	1	Unclassified Bacterium | Mollicutes bacterium, ascidians in eel pond [85.55%; EF137401.2], Anemonia viridis [86.43%; KC862086.1]
	2.43	6	Unclassified Rhodobacteraceae | Lophelia pertusa (cold water coral) [97.52%; FJ041447.1], Stylophora pistillata (coral) [96.26%; KC669141.1]
			Unclassified Rhodobacteraceae | Tropicbacter sp. from marine sponge [100%; KP412857.1, MH818487.1]
			Unclassified Rhodobacteraceae | Litopenaeus vannamei gut (shrimp) [99.5%; MK589151.1], diseased Montastraea faveolata (coral) [99.5%; FJ203299.1]
Clostridiales [Lachnospiraceae, Ruminococcaceae]	2.11	13	Unclassified Family XIII | endolithic bacteria from marine intertidal outcrop [99.51%; KT977254.1], healthy Montastraea faveolata (coral) [97.79%; FJ203646.1]
			Anaerococcus sp. | Mouse cecum [100%; KY672406.1]
			Ruminococcus torques group | Wastewater treatment system [99.75%; LR637623.1]
Cytophagales [Cyclobacteriaceae, Spirosomaceae, Amoebophilaceae]	1.96	9	Unclassified Cyclobacteriaceae | Montastraea faveolata, Montastraea franksi (corals) [100%; GU118859.1, GU118562.1]
			Reichenbachiella sp. | Dinoflagellate culture [96.93%; KJ754644.1], Gulf of Mexico oil surface [95.27%; KF786696.1]
			Candidatus Amoebophilus sp. | Astrangia poculata, Cladocora caespitosa, Galaxea fascicularis (corals) [95.52-95.70%; MK175907.1, KU354136.1, JQ235892.1]
Alteromonadales [Alteromonadaceae]	1.63	8	Alteromonas sp. |Favia sp. (coral mucus layer adjacent to black band mat) [100%; EF433118.1]
			Two unclassified Alteromonadaceae | Alteromonas sp. from Mariana Trench [99.77%; MH010314.1], Xestospongia muta (sponge) [99.77%; CP031010.1], Polyhydroxyalkanoates producing bacteria [99.77%; KU521388.1]
Bacteria [unclassified]	1.21	1	Unclassified bacteria | Mollicutes bacterium from ascidians in eel pond [85.32%; EF137401.2], Anemonia viridis [86.18%; KC862086.1]
Flavobacteriales [Flavobacteriaceae, Weeksellaceae]	0.74	7	Tenacibaculum sp. | Flexibacter aurantiacus subsp. Copepodarum [99.06%; AB681014.1], Tenacibaculum sp. from biofilms that induce metamorphosis of marine polychaete [98.82%; MG819702.1]
			Chryseobacterium sp. | Candidatus Amoebinatus massiliae [100%; AY204874.1], Chryseobacterium sp. in goldfish gut [99.76%; MN935216.1]
			Tenacibaculum sp. | biofilms that induce metamorphosis of marine polychaete [99.29%; MG819702.1], shrimp gut [99.06%; KF342728.1]
Halanaerobiales [Halanaerobiaceae]	0.55	1	Halanaerobium sp. | Montastraea faveolata (healthy and diseased coral) [97.64–100%; FJ202891.1, JQ516458.1, FJ203280.1]
Chitinophagales [Chitinophagaceae]	0.48	4	Sediminibacterium sp. | tropical urban freshwater [100%; KX968184.1], ureolytic biocementation (carbonate precipitation) in soil [97.64%; MN656428.1]
			Unclassified Chitinophagaceae | Ciona intestinalis (ascidian) [97.64%; F799383.1], shrimp gut [96.94%; KP947105.1]
			Unclassified Chitinophagaceae | eutrophic freshwater lake [98.01%; EU273038.1], anaerobic digester [95.75%; MN157568.1]
Entomoplasmatales [Spiroplasmataceae]	0.46	1	Spiroplasma sp. | Arthropod-symbiotic Spiroplasma from shrimp [89.07 %; KR349130.1, KY115222.1]
Microtrichales [Microtrichaceae]	0.36	4	Unclassified Microtrichaceae Sva0996 marine group | Actinobacterium in Poecillastra compressa (deep sea sponge) [95.58%; KF597097.1], Fe-rich hydrothermal sediments [91.15%; FJ905720.1]
			Unclassified Microtrichaceae Sva0996 marine group | Actinobacterium in coral reef sediment [99.75%; JN874654.1], Porites lutea (coral) [98.27%; KP303904.1]
			IMCC26207 (Microtrichaceae) | Wastewater treatment system [100%; LR634799.1], sediments, lake water [99.75%; MF689304.1, KX367772.1]
Chthoniobacterales [Chthoniobacteraceae]	0.26	1	Candidatus Udaeobacter sp. | Mountain forest and soil at CO2 spring [100%; MG716938.1, HF952262.1]
Saccharimonadales [unclassified]	0.24	1	Unclassified Saccharimonadales | Soil [96.05%; JQ367084.2], planktonic bacteria [91.36%; Q472788.1]
Bacteria [unclassified]	0.22	1	Unclassified Bacteria| Mollicutes bacterium from ascidians in eel pond [85.55%; EF137401.2], Anemonia viridis [86.43%; KC862086.1]
Bdellovibrionales [Bdellovibrionaceae]	0.21	4	Peredibacter sp. | biofilm on a copper-based antifouling paint, seawater [99.76%; JN594639.1, MH121376.1], Favia sp. (healthy and diseased coral) [98.12%; GU472125.1]
			Peredibacter sp. | sediments [96.71%; KC925129.1], Ciona intestinalis (ascidian) [96.05%; KF799703.1], crab [96.01%; KC917599.1]
			Peredibacter sp. | seawater [100%; MH121376.1], Favia sp. (healthy and diseased coral) [98.19%; GU472125]
Desulfobacterales [Desulfobacteraceae]	0.19	1	Desulfatitalea sp. | Montastraea faveolata (coral) [100%; JQ516448.1]
Betaproteobacteriales [Burkholderiaceae]	0.19	4	Burkholderia-Caballeronia-Paraburkholderia | human blood [99.77%; AB374482.1], Bradyrhizobium sp. from beech tree roots [99.53%; KX023689.1]
			Ralstonia sp. | Ralstonia pickettii from soil, pinapple roots, other plants [100%; MT322968.1, LR797737.1, MT341804.1]
			Bordetella sp. | Burkholderia bacterium from lupins and grass roots [99.77%; JN590346.1, LC031362.1], Bordetella sp. from water and sediment of abandoned uranium mine [99.77%; KF441609.1]
Porites “I” recipient microbiomes
Order [families included]	Relative abundance	No. of ASVs	Lowest taxonomic classification (SILVA) | sources and nearest relatives [% similarity; GenBank accession#]
Oceanospirillales [Endozoicomonadaceae]	4.64	9	Endozoicomonas sp. | Porites lutea (healthy coral) [99.77%; KF179706.1, KF179699.1], Porites compressa, Porites lobata [99.53%; FJ930621.1]
			Endozoicomonas sp. | Porites lutea (healthy coral) [100%; KF180095.1, KF180125.1]
			Kistimonas sp. | Neofibularia nolitangere (sponge) [97.44%, EU816849.1], Alcyonium gracillimum (soft coral) [96.97%; JF925015.1]
Chlamydiales [Simkaniaceae]	0.10	1	Simkania negevensis Z | endolithic bacteria from marine intertidal outcrop [94.4 2%; KT979567.1], sediments from Mariana trench [94.64%; MG580090.1]
SAR324 Marine group B [class:Deltaproteobacteria]	0.05	2	SAR324 clade (Marine group B) HF0200_14D13 | Bacterioplankton [89.05-89.30%; MG875850.1, JN232995.1]
			SAR324 clade (Marine group B) HF0200_14D13 | Bacterioplankton [89.30-89.55%; MG875850.1, JN232995.1]
Nostocales Incertae Sedis	0.01	1	Oscillatoria SAG8.92 | endolithic bacteria from marine intertidal outcrop [99.26%; KT973113.1], Oculina patagonica and bleached Muricea elongata (corals) [99.02%; KU936867.1, DQ917838.1]
Cellvibrionales [Cellvibrionaceae]	0.01	1	Candidatus Endobugula sp. | corals in fish farm effluent [96.28%; GQ413096.1], Candidatus Endobugula glebosa in Bugula simplex (bryozoan) [96.28%; AY532642.1]
Bacteroidales [Marinifilaceae]	0.01	1	Marinifilum sp. | Montastraea faveolata (coral) [97.64%; FJ202823.1], corals in fish farm effluent [97.41%; GQ413742.1]
Spirochaetales [Spirochaetaceae]	0.003	1	Spirochaeta 2 sp. | Siderastrea stellata (bleached coral) [95.34%; JF835682.1], Millepora sp. (coral) [95.57%; HQ288601.1]