Land Use and Seasonal Effects on the Soil Microbiome of a Brazilian Dry Forest

Abstract

Drylands occupy approximately 41% of the Earth’s terrestrial surface. Climate change and land use practices are expected to affect biogeochemical cycling by the soil microbiome in these ecosystems. Understanding how soil microbial community might respond to these drivers is extremely important to mitigate the processes of land degradation and desertification. The Caatinga, an exclusively Brazilian biome composed of an extensive seasonal tropical dry forest, is exposed to variable spatiotemporal rainfall patterns as well as strong human-driven pressures. Herein, an integrated analysis of shotgun metagenomics approach coupled to meteorological data was employed to unravel the impact of seasonality and land use change on soil microbiome from preserved and agriculture-affected experimental fields in Caatinga drylands. Multivariate analysis suggested that microbial communities of preserved soils under seasonal changes were shaped primarily by water deficit, with a strong increase of Actinobacteria and Proteobacteria members in the dry and rainy seasons, respectively. In contrast, nutrient availability notably played a critical role in driving the microbial community in agriculture-affected soils. The strong enrichment of bacterial genera belonging to the poorly-known phylum Acidobacteria (‘ Candidatus Solibacter’ and ‘ Candidatus Koribacter’) in soils from dry season affected by ferti-irrigation practices presupposes a contrasting copiotrophic lifestyle and ecological role in mitigating the impact of chemical fertilization. Functional analyses identify overrepresented genes related to osmotic stress response (synthesis of osmoprotectant compounds, accumulation of potassium ions) and preferential carbon and nitrogen utilization when comparing the microbiome of preserved soils under seasonal changes, reflecting differences in the genetic potential for nutrient cycling and C acquisition in the environment. However, the prevalence of nitrosative stress and denitrification functions in irrigation/fertilization-affected soils of the dry season clearly suggest that nutrient input and disruption of natural water regime may impact biogeochemical cycles linked to the microbial processes, with potential impacts on the ecosystem functionality. These findings help to better understand how natural seasonality and agricultural management differentially affect soil microbial ecology from dry forests, providing support for the development of more sustainable land management in dryland ecosystems.

The Aedes albopictus (Diptera: Culicidae) microbiome varies spatially and with Ascogregarine infection

“…Other environmental variables such as land use could play a stronger role in the heterogeneity seen in microbiomes. For example, land use practices are expected to affect biogeochemical cycling and microbiome compositions of soil [ 66 ]. Similarly, these types of effects might modulate the microbiomes of different mosquito populations in urban, rural, agricultural, and natural environments, where land use and management practices vary.…”

16S rRNA Gene Amplicon Based Metagenomic Signatures of Rhizobiome Community in Rice Field During Various Growth Stages

“…Enriched dominant genera common to all location included Ca . Koribacter (nitrogen metabolism) (Júnior et al, 2019), Ca . Solibacter (nitrogen metabolism), Clostridium (nitrogen-fixing) (Doni et al, 2014), Pseudonocardia (siderophore production), Geoalkalibacter (syntrophic organic matter degradation) (Neveling et al, 2017), Saccharopolyspora (phosphate-mineralizing) (Franco-Correa and Chavarro-Anzola, 2016), and Acidobacterium (indole-3-acetic acid production) (Kielak et al, 2016b).…”

Molecular, Physiological, and Symbiotic Characterization of Cowpea Rhizobia from Soils Under Different Agricultural Systems in the Semiarid Region of Brazil

“…Approximately 120,000 ha are currently irrigated, and the region has the potential to reach about 360,000 ha (Leão and Moutinho 2014). The intensification and expansion of crop areas directly affect soil characteristics and impact the diversity of the microbial populations (Bissett et al 2013;Lacerda-Júnior et al 2019). Combined with the modification of natural vegetation, the types of agricultural use can strongly influence native microorganisms with great biotechnological potential, such as the legume-associated nitrogen-fixing bacteria, collectively known as rhizobia.…”