Fig. 4

Effects of buffers and storage conditions (time and temperatures) on viral diversity. A Distribution of sequencing reads into the different taxonomic categories as viral, human, bacterial, fungi and unknown origin. To check the presence of non-viral DNA sequences, 50,000 random forward reads were evaluated according to their match to a range of viral, bacterial, and human reference genomes and protein databases. No reads (in 50,000 reads) matched the 18S rRNA gene sequences in all the samples. B The effect of buffers on the viral overall alpha diversity with the measurement of Observed taxa and Shannon diversity index. NS indicates not significant, one asterisk indicates a significant difference (p < 0.05, t test). C Representative taxonomic distribution (relative abundance) of the sequenced viromes. The relative distribution is described at the taxonomical level of the family. The taxonomy of contigs was determined by querying the viral contigs against a database containing taxon signature genes for virus orthologous group hosted at https://www.vogdb.org. The unclassified are the contigs that cannot be assigned to any known viral taxonomy at the family level, the unknown is the contigs that are related to “viral dark matter”. D Principal coordinates analysis (PCoA) plots of bray-Curtis distance matrices. PCoA was used to plot the beta diversity of viral-associated communities using the bray matrix. Different colors indicate different buffers, different shapes indicate different time points. For each axis, in square brackets, the percent of variation explained was reported