High stability of faecal microbiome composition in guanidine thiocyanate solution at room temperature and robustness during colonoscopy

Materials and methods The experimental protocol was approved by the institutional review board (National Cancer Center, #2013-244) and written informed consent was obtained. Participants were 8 healthy Japanese males (age 30-46 years). Exclusion criteria were use of antibiotics in the previous year, previous colonoscopy, smoking, alcohol consumption, and history of appendectomy, diabetes, cardiovascular diseases or mental disorders (Table S1). Participants took a commercial low-residue diet one day before colonoscopy and laxatives (sennoside) at night. Bowel-cleansing agent (Muben: sodium chloride 2.93 g, potassium chloride 1.485 g, sodium bicarbonate 3.37 g, anhydrous sodium sulfate 11.37 g in 2 L water) was applied to induce defecation. Faecal DNA was amplified at the V4 region of 16S rRNA gene using polymerase chain reaction with PrimeSTAR GXL DNA Polymerase (Takara Bio, Shiga, Japan). Sequencing was performed using a 300-bp paired-end sequencing protocol on the Illumina MiSeq platform (Illumina, San Diego, California, USA). Amplicon sequences were assigned to taxa of the microbial reference 16S rRNA gene sequence database using a pipeline as described. Table S1. Demographic information. Subject ID Gender Age BMI Colonoscopic findings A M 32 19.8 Hyperplastic polyps B M 39 27.6 Diverticulum C M 34 25 No appreciable disease D M 46 23.5 No appreciable disease E M 45 30.1 No appreciable disease F M 32 22.5 No appreciable disease G M 30 20.6 No appreciable disease H M 31 25.6 No appreciable disease