1 Table S1. The CsTFA BDs of the selected RNA fractions and the analyzed sequence number in Illumina sequence libraries Mixing ratio of the E. coli RNA 0.05% 0.01% Density fraction BDb mixture 1H 2H L 1.796 1.789 1.767 (±0.005) (±0.005) (±0.002) rep1=32,394 rep1=31,917 rep1=39,564 rep2=26,367 rep2=23,903 rep2=32,384 rep3=31,106 rep3=31,455 rep3=34,984 rep1=5,660 rep1=1,966 rep1=163 rep2=2,611 rep2=2,147 rep2=126 rep3=3,956 rep3=257 rep3=16 Unlabeled mixture 1H 2H L 1.797 1.791 1.769 (±0.006) (±0.004) (±0.004) rep1=31,310 rep1=56,046 rep1=40,907 rep2=65,264 rep2=86,749 rep2=191,184 rep3=35,006 rep3=39,135 rep3=62,195 rep1=505 rep1=393 rep1=169 rep2=201 rep2=201 rep2=928 rep3=1,356 rep3=75 rep3=30 1H 2H L 1H 2H L 1H 2H L 1.798 1.791 1.768 1.797 1.792 1.768 1.798 1.792 1.772 (±0.004) (±0.004) (±0.003) (±0.006) (±0.006) (±0.005) (±0.002) (±0.001) (±0.003) rep1=32,934 rep1=35,907 rep1=38,037 rep1=45,271 rep1=28,150 rep1=42,636 rep1=25,790 rep1=32,490 rep1=31,356 rep2=12,480 rep2=23,654 rep2=47,652 rep2=22,384 rep2=51,622 rep2=683,517 rep2=99,112 rep2=30,841 rep2=19,913 rep3=27,311 rep3=36,115 rep3=35,156 rep3=28,764 rep3=49,499 rep3=44,614 rep3=35,428 rep3=29,923 rep3=51,043 rep1=1,562 rep1=603 rep1=209 rep1=429 rep1=204 rep1=164 rep1=859 rep1=516 rep1=107 rep2=582 rep2=320 rep2=110 rep2=203 rep2=305 rep2=883 rep2=2,846 rep2=236 rep2=81 rep3=932 rep3=322 rep3=14 rep3=271 rep3=342 rep3=183 rep3=852 rep3=144 rep3=14 1H 2H L 1.799 1.790 1.770 (±0.006) (±0.006) (±0.006) rep1=21,465 rep1=34,642 rep1=36,667 rep2=20,610 rep2=29,624 rep2=66,080 rep3=37,767 rep3=25,523 rep3=32,490 rep1=174 rep1=323 rep1=125 rep2=98 rep2=80 rep2=710 rep3=372 rep3=121 rep3=26 mixture 1H 2H L 1.797 1.791 1.770 (±0.004) (±0.005) (±0.004) rep1=32,760 rep1=44,891 rep1=45,296 rep2=231,738 rep2=38,758 rep2=22,278 rep3=32,114 rep3=24,266 rep3=40,634 rep1=934 rep1=1,046 rep1=177 rep2=655 rep2=95 rep2=72 rep3=178 rep3=134 rep3=20 Unlabeled mixture 1H 2H L 1.797 1.790 1.770 (±0.005) (±0.007) (±0.001) rep1=36,891 rep1=45,307 rep1=47,268 rep2=249,377 rep2=46,497 rep2=49,897 rep3=35,212 rep3=36,019 rep3=36,911 rep1=849 rep1=717 rep1=211 rep2=4,557 rep2=98 rep2=192 rep3=179 rep3=165 rep3=10 13C 13C mixture Unlabeled mixture 0.001% 13C mixture Unlabeled mixture 0.0001% Number of sequences Fractiona Mixtures 13C Sequences from total bacteria c Sequences from E. coli c 2 3 a Density fractions of RNA are indicated as “1H” (the heaviest), “2H” (second-heaviest), and “L” (light) fractions. 4 b The CsTFA BDs (g ml−1) of the RNA fractions were determined from each set of different tubes for isopycnic centrifugation done in 1 5 triplicate. The standard deviations of three replications are indicated in parentheses. 6 c 7 and the sequence number in each replication is presented. The 16S rRNA sequences were phylogenetically characterized from each set of the different sequence libraries constructed in triplicate, 8 9 10 2