TABLE 1.

Summary of taxa assimilating a ¹³C-labeled substrate after a 1-week period

Taxon	13C-enriched organic matter (heterotrophic assay)			13C-labeled bicarbonate (autotrophic assay)
	Avg bootstrapped A median valuea of OTUs	No. of OTUs that did not overlap zero	No. of sequences (% of total)	Avg bootstrapped A median value of OTUs	No. of OTUs that did not overlap zero	No. of sequences (% of total)
Bacterial group
AC1	0.174	1	191 (0.02)
Acidobacteria	0.147	53	53,330 (4.29)	0.090	66	142,863 (8.36)
Actinobacteria	0.141	43	37,912 (3.05)	0.090	118	127,476 (7.46)
Aminicenantes	0.150	1	304 (0.02)	0.083	1	128 (0.01)
Armatimonadetes				0.095	1	193 (0.01)
Bacteroidetes	0.133	101	119,842 (9.6)	0.073	33	37,426 (2.19)
Chlorobi	0.132	3	1,063 (0.09)	0.076	2	459 (0.03)
Chloroflexi	0.125	108	122,862 (9.9)	0.090	90	116,303 (6.80)
Cloacimonetes	0.164	1	371 (0.03)
Cyanobacteria	0.086	2	11,716 (0.94)
Elusimicrobia	0.172	3	650 (0.05)
Firmicutes	0.130	25	89,386 (7.19)	0.120	6	3,125 (0.18)
Gemmatimonadetes	0.157	13	7,543 (0.61)	0.073	11	16,020 (0.94)
Ignavibacteria	0.136	10	12,469 (1.00)	0.085	4	2,069 (0.12)
Modulibacteria (KSB3)	0.099	1	192 (0.02)
Latescibacteria	0.170	5	2,202 (0.18)	0.089	10	6,282 (0.37)
Nitrospinae	0.160	2	6,309 (0.51)	0.083	2	5,335 (0.31)
Nitrospirae	0.146	18	17,753 (1.43)	0.082	11	22,886 (1.34)
Omnitrophica	0.113	2	1,922 (0.15)
Planctomycetes	0.120	35	17,644 (1.42)	0.079	80	43,712 (2.56)
Proteobacteria	0.145	298	684,269 (55)	0.092	309	1,079,407 (63)
Spirochaetes	0.134	6	1,682 (0.14)
Verrucomicrobia	0.138	89	51,909 (4.18)	0.087	52	105,543 (6.17)
Archaeal group
Bathyarchaeota	0.118	1	862 (0.07)
Euryarchaeota				0.087	1	307 (0.02)
Thaumarchaeota	0.108	2	526 (0.04)
Woesearchaeota (DHVEG-6)				0.076	1	277 (0.02)
Total			1,242,909			1,709,811

^aMedian of bootstrapped excess atom fraction (EAF) values (see reference 14).