Ecological co-occurrence and soil physicochemical factors drive the archaeal community in Amazonian soils

We evaluated the co-occurrence of archaeal taxonomic groups and soil physicochemical characteristics in relation to the structuring of the archaeal community in Amazonian soil under different land use systems. Soil samples were collected in primary forest (PF), secondary forest (SF), agricultural systems (AG) and cattle pastures (PA). Archaeal community composition was revealed based on high-throughput amplicon sequencing of the 16S rRNA gene. The results revealed co-occurrence of archaeal classes, with two groups formed: Thaumarchaeota classes, including South Africa Gold Mine-Group 1 (SAGMG-1), Crenarchaeotic group (SCG) and Crenarchaeota candidate division YNPFFA, with predominance in PF and SF; and Bathyarchaeota_unclassified, Methanomicrobia and Methanobacteria (Euryarchaeota) with the FHMa11 terrestrial group, with predominance in PA. The number of co-occurrences between groups was lower in SF, AG and PA (approximately 30%) than in PF. The qPCR analysis revealed that PF also had the largest number of archaeal representatives. Soil texture may be a limiting factor of interactions between groups since the most representative groups, SAGMG-1 and the SCG (over 20% in all sites), were positively associated with coarse sand, the soil factor most correlated with the groups (33% of the total). These results suggest that interactions between archaeal classes belonging to different phyla may be dependent on the num-ber of individuals in the soil environment. In this context, differences in soil physical structure among the land use systems can reduce the representatives of key groups and consequently the co-occurrence of Archaea, which could compromise the natural dynamics of this complex environment.

Automated summary

This study evaluated the co-occurrence relationships between archaeal taxonomic groups and soil physicochemical characteristics in Amazonian soil under different land use systems. It was found that certain archaeal classes dominated in primary and secondary forests, while others were more prevalent in agricultural systems and pastures. The number of co-occurrences between archaeal groups was lower in secondary forests, agricultural systems, and pastures compared to primary forests. These results suggest that soil texture may play a role in mediating interactions between archaeal groups.