16S of soil: H4_1
Amplification success was verified by mixing PCR products with an equal volume of 1 loading buffer containing SYBR Green I and electrophoresing on 2% agarose gels. Products displaying dominant bands between 400450 bp were selected for downstream processing. Equimolar concentrations of PCR amplicons were pooled and purified using the GeneJET Gel Extraction Kit (Thermo Fisher Scientific). Sequencing libraries were constructed with the NEBNext Ultra DNA Library Prep Kit (New England Biolabs) following manufacturer protocols, with unique index codes assigned to each sample.