16S rRNA of solar panel's surface
NextSeq Illumina libraries were constructed, targeting the hypervariable V3 and V4 regions of the 16S gene (Forward = 5 TCGTCGGCAGCGTCAGATGTGTATAAGAGACAGCCTACGGGNGGCWGCAG; Reverse = 5 GTCTCGTGGGCTCGGAGATGTGTATAAGAGACAGGACTACHVGGGTATCTAATCC) and targeting the ITS region (Forward = 5CTTGGTCATTTAGAGGAAGTAA3; Reverse = 5GCTGCGTTCTTCATCGATGC3). Then, Illumina sequencing adaptors and dual-index barcodes (Nextera XT index kit v2, FC-131-2001) were added, and libraries were normalized and pooled. The pools were loaded onto the MiSeq reagent cartridge v3 (MS-102-3003), spiked with 10% PhiX control and sequencing was conducted using paired-ends on an Illumina MiSeq sequencing system. Rarefaction curves were saturated for all samples, indicating that sequencing was deep enough to assess all microbial diversity (Fig. S6). Mean values of 36 533 and 52 192 sequences were obtained for the 16S gene and the ITS region, respectively, with a minimum of 9669 and a maximum of 61 764 sequences for the 16S gene, and a minimum of 25 640 and a maximum of 68 942 sequences for the ITS region.