Measuring Total COD and Microbiome Analysis

Total COD was determined by adding 400 µL of solution, medium, or lysate to a HACH COD vial (HACH, High Range 20–1500 mg COD/L) with 1600 μL of DI water followed by a 2-h incubation at 150 °C (HACH DRB200). The vials were then cooled and measured for COD concentration in mgCOD/L using a spectrophotometer (HACH DR2800 Laboratory Spectrophotometer). For microbiome composition analysis, we performed 16S rRNA gene amplicon sequencing using Illumina sequencing technology and found core differences as described [24 (link),25 (link)]. Further detailing regarding the 16S rRNA amplicon sequences is presented in Supplementary File S5.