title: negative control: PCR mix no DNA
design: In the 16S-V4 library, a one-step PCR with 505f:GTGCCAGCMGCCGCGGTAA and 806r:GGACTACHVGGGTWTCTAAT PCR primers was used, followed by batch normalization with SequalPrep plates and pooling. Quality checked and quantification was performed with Qubit and Illumina qPCR assays.  In the ITS library, a two-step PCR with ITS1f:CTTGGTCATTTAGAGGAAGTAA and ITS2:GCTGCGTTCTTCATCGATGC PRC primer swas used, with Fluidigm common oligos CS1/CS2 fused to their 5' ends. PCR product was amplified in a secondary PCR using dual indexed, Illumina compatible primers which target the Fluidigm CS1/CS2 oligomers at the ends of the primary PCR products. Indexing, normaliztrion, quality checked and quantification was performed same as for the 16S.