Physical-chemical influence on taxonomic and functional
diversity
To identify key environmental drivers
of community taxonomy (at phylum level) and function (SEED level 1),
Spearman correlations were calculated; then only significant (p< 0.05) and strong correlations (r > −0.6
or 0.6) were considered. In general, the phyla that positively
correlated with temperature were Euryarchaeota, Crenarchaeota,
Korarchaeota, Nanoarchaeota, Thermotogae, and Aquificae, whereas several
phyla were negatively correlated with temperature (e.g. Acidobacteria,
Bacteroidetes, Spirochaetes, Actinobacteria, Verrucumicrobia,
Nitrospirae, Deinococcus-Thermus, and Gemmatimonadetes, among others)
(Figure 5a). The phyla that negatively correlated with ammonia were
Proteobacteria, Thaumarchaeota, Euryarchaeota, and Deferribacteres;
those positively correlated were Firmicutes, Acidobacteria,
Cyanobacteria, and Spirochaetes, among others. All significant nitrate
correlations were positive, including phyla such as Firmicutes,
Nitrospirae, Thermotogae, etc. Sulfate showed significant positive
correlations with Proteobacteria, Thaumarchaeota, Euryarchaeota,
Deferribacteres and Crenarchaeota, and negative correlations with phyla
such as Acidobacteria, Cyanobacteria, Actinobacteria, and
Verrucomicrobia, among others. Other parameters exhibited positive and
negative correlations with several phyla, such as organic matter,
organic carbon, B, Cu (uniquely negative correlations), Fe (uniquely
negative correlations), Na, K, Ca, Mg and Al (Figure 5a, Supplementary
Table 3).
The functional categories (SEED level 1) which presented positive
correlations with temperature were “DNA metabolism”, “nucleosides and
nucleotides” and “RNA metabolism”, and those which exhibited negative
correlations were “fatty acids, lipids and isoprenoids”, “iron
acquisition”, “metabolism of aromatic compounds”, “phosphorus
metabolism”, “photosynthesis”, “secondary metabolism”, “stress
response”, and “sulfur metabolism” (Figure 5b). Ammonia was
negatively correlated with functions such as “carbohydrates”,
“motility and chemotaxis”, “respiration” and “RNA metabolism”,
whereas positive correlations comprised functions as “amino acids and
derivatives” and “cofactors, vitamins, prosthetic groups and
pigments”. Nitrate also presented negative correlations with
“carbohydrates”, “dormancy and sporulation” and “phages, prophages,
transposable elements and plasmids”. In contrast, sulfate was
positively correlated with “carbohydrates”, “DNA metabolism”,
“motility and chemotaxis”, “respiration” and “RNA metabolism”.
Other parameters exhibited positive and negative correlations with
several functions, such as organic matter, organic carbon, B, Cu, Fe,
Si, Na, K, Ca, Mg and Al (Figure 5b, Supplementary Table 3).