D-1 sequencing
16S rRNA gene V3-V4 hypervariable regions were amplified for bacterial community profiling. Primers 341F (5'-CCTACGGGNGGCWGCAG-3') and 805R (5'-GACTACHVGGGTATCTAATCC-3') were used. PCR reactions contained 10 ng/L microbial DNA (2L), 10 M primers (1L each), Hieff Robust PCR Master Mix (2X, 15L; Yeasen, #10105ES03) in 30L volume. Thermocycling: 95C 3 min; 5 (95C 30s, **45C 30s**, 72C 30s); 20 (95C 30s, **55C 30s**, 72C 30s); 72C 5 min. Amplicon size (~550 bp) was verified by 2% agarose/EB gel electrophoresis.