SRX265560 MES1-granules SRP021100 Active microbial populations on cathode granules within acetate-generating microbial electrolysis cell MES1. Approximately 10 mL of graphite granules (cathode material) were flash-frozen and stored at -80 degrees C until further processing. To process, Buffer RLT (Qiagen; RNeasy kit), β-mercaptoethanol (10 μL/ mL of RLT), and silicon carbide beads (DNase- and RNase-free mixture of 0.1 mm and 1 mm) were added to frozen granules. Samples were then incubated at room temperature for 10 min and subsequently subjected to 5 freeze/thaw cycles (i.e. freeze in liquid nitrogen, thaw at 55oC, vortex 6 minutes, and repeat). Following this, cellular debris and granules were pelleted by centrifugation. The RNA from the resultant supernatant was purified using an RNeasy kit (Qiagen), and residual DNA was removed via DNase treatment (TURBO DNA-free kit, ABI). Reverse transcription (RT) was carried out with 100 ng of total RNA using random hexamers (SuperScript III, Life Technologies) according to manufacturer’s instructions. To generate rRNA amplicons, replicate PCR was performed with universal Bacterial primers for the V1-V3 region of 16S rRNA using 1 µL of RT template. Primers included a 1:1 (mol:mol) mix of B27f (5'-AGA GTT TGA TCC TGG CTC AG-3') and B27f-degenerate (5'-AGA GTT TGA TYM TGG CTC AG-3'), and the reverse primer U529r (5'-ACC GCG GCK GCT GRC-3'). Barcode was added to 5' end of the reverse primer: (5'-CGT GTC TCT A-3'). PCR replicates were pooled and cleaned (Qiagen, PCR Clean-up Kit) before sequencing with PacBio, 2 looks at 45 minutes. Only circular consensus sequences were considered in analyses.Deposited sequences are full-length, untrimmed reads but only those that were used in analyses (those making it past quality control). SRS412624 MES1, granules MES1-granules AMPLICON METAGENOMIC RT-PCR 0 0 Application Read Forward 1 PacBio RS SRX265561 MES1-supernatant SRP021100 Active microbial populations in cathode chamber supernatant within acetate-generating microbial electrolysis cell MES1. Approximately 40 mL of supernatant was filtered onto a 0.22 μm Sterivex GP filter unit (Millipore) that was flash-frozen and stored at -80 degrees C until further processing. To process, Buffer RLT (Qiagen; RNeasy kit), β-mercaptoethanol (10 μL/ mL of RLT), and silicon carbide beads (DNase- and RNase-free mixture of 0.1 mm and 1 mm) were added to frozen Sterivex filter units. Samples were then incubated at room temperature for 10 min and subsequently subjected to 5 freeze/thaw cycles (i.e. freeze in liquid nitrogen, thaw at 55oC, vortex 6 minutes, and repeat). Following this, cellular debris was pelleted by centrifugation. The RNA from the resultant supernatant was purified using an RNeasy kit (Qiagen), and residual DNA was removed via DNase treatment (TURBO DNA-free kit, ABI). Reverse transcription (RT) was carried out with 100 ng of total RNA using random hexamers (SuperScript III, Life Technologies) according to manufacturer’s instructions. To generate rRNA amplicons, replicate PCR was performed with universal Bacterial primers for the V1-V3 region of 16S rRNA using 1 µL of RT template. Primers included a 1:1 (mol:mol) mix of B27f (5'-AGA GTT TGA TCC TGG CTC AG-3') and B27f-degenerate (5'-AGA GTT TGA TYM TGG CTC AG-3'), and the reverse primer U529r (5'-ACC GCG GCK GCT GRC-3'). Barcode was added to 5' end of the reverse primer: (5'-CGT GTC TCT A-3'). PCR replicates were pooled and cleaned (Qiagen, PCR Clean-up Kit) before sequencing with PacBio, 2 looks at 45 minutes. Only circular consensus sequences were considered in analyses. Deposited sequences are full-length, untrimmed reads but only those that were used in analyses (those making it past quality control). SRS412625 MES1, supernatant MES1-supernatant AMPLICON METAGENOMIC RT-PCR 0 0 Application Read Forward 1 PacBio RS SRX265562 MES2-granules SRP021100 Active microbial populations on cathode granules within acetate-generating microbial electrolysis cell MES2. Approximately 10 mL of graphite granules (cathode material) were flash-frozen and stored at -80 degrees C until further processing. To process, Buffer RLT (Qiagen; RNeasy kit), β-mercaptoethanol (10 μL/ mL of RLT), and silicon carbide beads (DNase- and RNase-free mixture of 0.1 mm and 1 mm) were added to frozen granules. Samples were then incubated at room temperature for 10 min and subsequently subjected to 5 freeze/thaw cycles (i.e. freeze in liquid nitrogen, thaw at 55oC, vortex 6 minutes, and repeat). Following this, cellular debris and granules were pelleted by centrifugation. The RNA from the resultant supernatant was purified using an RNeasy kit (Qiagen), and residual DNA was removed via DNase treatment (TURBO DNA-free kit, ABI). Reverse transcription (RT) was carried out with 100 ng of total RNA using random hexamers (SuperScript III, Life Technologies) according to manufacturer’s instructions. To generate rRNA amplicons, replicate PCR was performed with universal Bacterial primers for the V1-V3 region of 16S rRNA using 1 µL of RT template. Primers included a 1:1 (mol:mol) mix of B27f (5'-AGA GTT TGA TCC TGG CTC AG-3') and B27f-degenerate (5'-AGA GTT TGA TYM TGG CTC AG-3'), and the reverse primer U529r (5'-ACC GCG GCK GCT GRC-3'). Barcode was added to 5' end of the reverse primer: (5'- TAG TAT CAG C -3'). PCR replicates were pooled and cleaned (Qiagen, PCR Clean-up Kit) before sequencing with PacBio, 2 looks at 45 minutes. Only circular consensus sequences were considered in analyses.Deposited sequences are full-length, untrimmed reads but only those that were used in analyses (those making it past quality control). SRS412626 MES2, granuals MES2-granules AMPLICON METAGENOMIC RT-PCR 0 0 Application Read Forward 1 PacBio RS SRX265564 MES2-supernatant SRP021100 Active microbial populations in cathode chamber supernatant within acetate-generating microbial electrolysis cell MES2. Approximately 40 mL of supernatant was filtered onto a 0.22 μm Sterivex GP filter unit (Millipore) that was flash-frozen and stored at -80 degrees C until further processing. To process, Buffer RLT (Qiagen; RNeasy kit), β-mercaptoethanol (10 μL/ mL of RLT), and silicon carbide beads (DNase- and RNase-free mixture of 0.1 mm and 1 mm) were added to frozen Sterivex filter units. Samples were then incubated at room temperature for 10 min and subsequently subjected to 5 freeze/thaw cycles (i.e. freeze in liquid nitrogen, thaw at 55oC, vortex 6 minutes, and repeat). Following this, cellular debris was pelleted by centrifugation. The RNA from the resultant supernatant was purified using an RNeasy kit (Qiagen), and residual DNA was removed via DNase treatment (TURBO DNA-free kit, ABI). Reverse transcription (RT) was carried out with 100 ng of total RNA using random hexamers (SuperScript III, Life Technologies) according to manufacturer’s instructions. To generate rRNA amplicons, replicate PCR was performed with universal Bacterial primers for the V1-V3 region of 16S rRNA using 1 µL of RT template. Primers included a 1:1 (mol:mol) mix of B27f (5'-AGA GTT TGA TCC TGG CTC AG-3') and B27f-degenerate (5'-AGA GTT TGA TYM TGG CTC AG-3'), and the reverse primer U529r (5'-ACC GCG GCK GCT GRC-3'). Barcode was added to 5' end of the reverse primer: (5'-CGT GTC TCT A-3'). PCR replicates were pooled and cleaned (Qiagen, PCR Clean-up Kit) before sequencing with PacBio, 2 looks at 45 minutes. Only circular consensus sequences were considered in analyses. • Deposited sequences are full-length, untrimmed reads but only those that were used in analyses (those making it past quality control). SRS412627 MES2, supernatant MES2-supernatant AMPLICON METAGENOMIC RT-PCR 0 0 Application Read Forward 1 PacBio RS