Fig. 7

Alpha and beta diversity of potential Legionella hosts. Next-generation sequencing (NGS) was performed using universal primers, designed for the V9 region of the 18S rRNA gene. Raw data were pre-filtered to retain Amoebozoa, Ciliophora (Ciliates), and Percolozoa (Excavata) amplicon sequence variants (ASVs), present at a minimal frequency of 20 reads across all samples, in a minimum of 2 samples. Water (n = 40) and biofilm (n = 25) samples were analyzed separately. Alpha and beta diversity analyses were performed at a rarefaction depth of 986 reads. a + b Alpha diversity of potential Legionella hosts across (a) spring clusters and (b) collection dates. Shannon’s entropy is presented for water (left panels) and biofilm (right panels) samples. Faith’s PD, Pielou’s evenness, and observed ASVs are presented in Supplementary Fig. 11a and b. Kruskal–Wallis test results and post hoc via Wilcox tests are presented in Supplementary Table 19. c + d Beta diversity of potential Legionella hosts across spring clusters. c Jaccard and d Bray–Curtis are presented for water (left panels) and biofilm (right panels) samples. Beta diversity statistical significance was tested via PERMANOVA and PERMDISP analyses (Supplementary Tables 20 and 21)