Co-digestion (CHO concentration equal to VL4, but with different proportions of residues)
The samples were collected from H4, H6, H9 and VH assays, washed in PBS buffer (NaCl 8%, KCl 0.2%, Na2HPO4 1.44%, KH2PO4 0.24%) (Green, 2012). Then, DNA extraction was carried out using the FastDNA SPIN Kit for Soil (MP Biomedicals TM) following manufacturer instructions. The extracted DNA was quantified (ng/L) and its quality was verified on Nanodrop 2000 Spectrophotometers (ThermoFisher Scientific) and Qubit fluormeter (Life Technologies). Finally, the DNA library (paired end 150 pb) was prepared using Nextera XT kit (Illumina, San Diego, CA) and sequenced in the  NGS sequencing facility of the Biology Department (University of Padova, Italy) using the Ilumina NextSeq 500 platform (Illumina Inc., San Diego, CA).