title: Interaction of manganese-oxidizing bacteria and nitrogen-cycling microbes in oligotrophic conditions
design: The genomic DNA of each biofilm sample was extracted using the PowerSoil DNA Isolation Kit. The amplification of the hypervariable region (V4V5) of the 16S rRNA gene was conducted by polymerase chain reaction (PCR) thermal cycler (Applied Biosystems Veriti, Thermo Fisher Scientific). The bacterial universal primers V4V5 of the 16S rRNA gene were, 515F: 5-GTGCCAGCMGCCGCGGTAA-3; 907R: 5-CCGTCAATTCCTTTGAGTTT-3, and the archaeal universal primers were V4, U519F: 5-CAGYMGCCRCGGKAAHAC-3; 806R: 5-GGACTACNSGGGTMTCTAAT-3.