Abstract:
Land-use change from natural to managed agricultural ecosystems significantly impacts
soil bacterial diversity and function. The Eastern Free State (EFS) is one of the most productive
agricultural regions in South Africa. However, no studies aiming to understand the changes in
bacterial diversity, composition and function due to land-use change in this area have been conducted.
This study investigated, using high-throughput 16S rRNA gene amplicon sequencing, the e ects
of long-term agriculture on bacterial diversity, composition and putative function in the EFS by
comparing microbiomes from lands that have been under agronomic activity for over 50 years
to those from uncultivated land. Results indicate that agriculture increased bacterial diversity.
Soil chemical analysis showed that land-use shifted soils from being oligotrophic to copiotrophic,
which changed bacterial communities from being Actinobacteria dominated to Proteobacteria dominated.
Predictive functional analysis using Phylogenetic Investigation of Communities by Reconstruction
of Unobserved States (PICRUSt) suggested that agricultural soil was abundant in genes associated
with plant fitness and plant growth promotion, while non-agricultural soil was abundant in genes
related to organic matter degradation. Together, these results suggest that edaphic factors induced by
long-term agriculture resulted in shifts in bacterial diversity and putative function in the EFS.
Description:
Supplementary Material: Figure S1: Sunburst chart showing the total relative abundance of bacterial phyla detected in investigated samples,
Figure S2: Rarefaction analyses of samples at phylum level, Figure S3: Unique and shared KEGG Orthologs
(KOs) between the agricultural and non-agricultural soils, Figure S4: Extended error bar plot for the six active
features (high-level subsystems) that had significant di erences between agricultural and non-agricultural samples,
Figure S5. Extended error bar plot showing the abundances of functions associated with plant interaction that
had significant di erences between agricultural and non-agricultural samples, Figure S6: Heat map showing
di erences in relative abundance of the 50 most abundant bacterial genera as revealed by ClustVis statistical
analysis, Figure S7. Relative abundance of di erent genera involved in plant growth promotion and plant fitness
between agricultural and non- agricultural soils.
