# Biogeographical Distribution of Bacteria in Soils with Identical Agricultural Practices: Impacts of Environmental Factors

## TL;DR

This study shows how environmental factors shape bacterial communities in the soil around maize and soybean roots in different South African climates.

## Contribution

The study reveals how climate and soil properties influence non-core bacterial taxa in rhizospheres under identical agricultural practices.

## Key findings

- Dominant bacterial phyla varied between semi-arid and subtropical regions, with Actinobacteriota and Pseudomonadota being prevalent in both.
- Environmental factors like temperature, moisture, pH, and soil texture significantly influenced the abundance of specific bacterial families.
- A core bacterial community was found to persist across regions, but non-core taxa showed strong environmental dependency.

## Abstract

Soil microbial communities are key drivers of plant health and productivity, influencing nutrient cycling and energy flow. This study investigated the impact of environmental variables on the bacterial communities within the rhizospheres of maize and soybean, two economically important crops, across contrasting South African climates with identical agricultural practices. Using 16S rRNA amplicon sequencing, we conducted a comparative analysis of rhizosphere bacterial communities in the semi-arid steppe of Free State and the subtropical region of Mpumalanga. In the semi-arid steppe, Actinobacteriota (36.5%), Pseudomonadota (24.4%), and Chloroflexi (12.8%) were dominant, while the subtropical region had higher proportions of Actinobacteriota (34.8%), Pseudomonadota (27.6%), and Acidobacteriota (12.6%). Our findings indicate that while a core bacterial community persists across regions, environmental factors significantly influence the diversity of non-core taxa. For instance, in Mpumalanga, correlation analysis suggested that the abundance of families like Burkholderiaceae and Symbiobacteraceae were influenced by moisture and minimum daily temperature while in Free State, families such as WS2 and Legionellaceae were influenced by maximum daily temperature, soil pH, and texture. These findings underscore the influence of climate and soil properties on the rhizosphere microbiome and highlight the importance of understanding these patterns for enhancing crop production in changing environmental conditions.

The online version contains supplementary material available at 10.1007/s00284-025-04404-w.