The influence of temperature on bacterial communities in arid soil microbiomes

Abstract

Despite their profound effects, we lack comprehensive mechanistic insights regarding the effects of temperature increases on dryland plant-associated microbiomes. This knowledge deficit is especially true for prominent plants in understudied dryland soils from Africa. To establish a baseline for predictive studies, we constructed soil microcosms to test the effects of environmental perturbations on microbial communities. Samples associated with prominent arid zone tree Acacia erioloba were collected. To study the effects of temperature, we incubated soils at 30°C and 40°C, respectively, for forty days. We used 16S rRNA gene amplicon sequencing and soil physicochemical parameters to determine bacterial diversity and the drivers of microbial community structure. The results suggest that some soil physicochemical variables may be more substantial drivers of microbial communities, masking the effects of temperature increases. In general, bacterial communities were dominated by ubiquitous taxa including Actinobacteria (39.1%), Firmicutes (36.1%), Proteobacteria (9.9%), Acidobacteria (4.6%), Chloroflexi (4.5%). Microhabitats differences appear to explain bacterial community composition, with higher relative abundances of Firmicutes in canopy soils and Actinobacteria and Chloroflexi in open soils. Distance-based redundancy analysis suggests that iron was a major determinant of bacterial diversity in canopy soils. However, other factors including copper and pH appear to be major drivers explaining bacterial community structure in open soils. Taken together, the data suggest that physicochemical variables in microhabitats may buffer the effects of short-term temperature increases on soil microbes in arid soils.