4.3. Niche differentiation of Bathyarchaeia groups in paddy soils
To the best of our knowledge, this represents the inaugural study investigating the niche differentiation of Bathyarchaeia in relation to the physicochemical characteristics of arable soils, including pH and the C/N ratio. Our Random Forest analysis unveiled MAT as the preeminent factor influencing the abundance ofBathyarchaeia in paddy soil (as depicted in Fig. 5a). The relative abundance of Bathyarchaeia and Bathy-6 exhibits a notably positive correlation with MAT (as seen in Fig. 4). This observation harmonizes with our recent global meta-analysis (Xue et al. 2023), underscoring the influence of temperature on Bathyarchaeiasubgroups in soils, as similarly documented by previous study (Xiang et al. 2017), who explored the impact of temperature onBathyarchaeia subgroups in soils via multivariate regression tree analysis (Xiang et al. 2017). The discovery of Bathyarchaeia in hot springs further accentuates its remarkable adaptability to high-temperature environments (Barns et al. 1996).
We found the significance of the C/N ratio as an important factor in regulating the relative abundance of Bathyarchaeia in paddy soils (Fig. 4 and Fig. 5). However, in oligotrophic environments, such as sea and mangrove sediments, TOC was reported to be the major limiting factors for the abundance of Bathyarchaeia , regulating the quantity of Bathyarchaeia (Pan et al. 2019; Yu et al. 2017). However, in paddy soils, organic matter and ammonia are abundant due to fertilization; therefore, the C/N ratio becomes the major factor associated with the abundance of Bathyarchaeia . The dominant subgroup differs in sediments and paddy soils, causing a niche differentiation. These results can elaborate our understanding of the niche preference of Bathyarchaeia in different environments and give suggestions for the enrichment of Bathyarchaeia .
The results of Mantel analysis suggested that soil pH is also a key factor regulating the Bathyarchaeia and Bathy-6 subgroups. SEM results further supported the important role of soil pH in influencing the community structure. The heatmap results also indicated that the abundance and number of ASVs also significantly correlate with soil pH. pH is a crucial factor in influencing bacterial, archaeal, and fungal community structures in soils (Jiao et al. 2019; Tedersoo et al. 2020; Tripathi et al. 2018), also influencing the community structure ofBathyarchaeia in mangrove sediments (Pan et al. 2019).