title: Co-electron donor CE ratio 1.5 mM/mM sample 1 day 21
design: Total genomic DNA was extracted from the samples using the TGuide S96 Magnetic Soil /Stool DNA Kit. The quality and quantity of the extracted DNA were examined using electrophoresis on a 1.8% agarose gel. DNA concentration and purity were determined with NanoDrop 2000 UV-Vis spectrophotometer. DNA passing quality assessment was fragmented. DNA fragments were further processed for end repairing, adding 3' A tail and adapter ligation. The products of proper size were selected and purified. The selected fragments were further amplified to construct the sequencing library. Qualified libraries were then processed for sequencing on Illumina platform. Sequences of low quality were removed. MEGAHIT was employed for metagenome assembly. Contigs shorter than 300 bp were removed. After assembly, QUAST[ was used to evaluate the assembly outputs. In coding gene prediction, MetaGeneMark was applied to identify coding regions in genome at default parameter settings. MMseqs2 was used to remove redundancy with similarity threshold at 90% and coverage threshold 80%. Protein sequences of non-redundant genes were BLAST against NCBI Nr database to obtain the corresponding annotation information of the sequence.