Early view

Georgina Asare, Vanya Popova, Mariana Petkova, Stefan Shilev, Orhan Dengiz

Abstract

Saline soils represent a major challenge to agricultural productivity, particularly in regions like Belozem, Bulgaria, where salinization is both naturally occurring and anthropogenically induced. This study investigates the microbial status of strongly saline soils through a combination of conventional microbiological methods and metagenomic sequencing. Soil respiration (SR), substrate induced respiration (SIR), colony-forming units (CFU), and enzymatic activities (β-glucosidase and dehydrogenase) were assessed alongside high-throughput 16S rRNA gene sequencing. Results indicate that increased soil salinity and gravimetric water content negatively affect microbial respiration and diversity. The microbial community was dominated by halotolerant taxa including Actinobacteriota, Proteobacteria, and Firmicutes. Soil respiration was significantly correlated with moisture, and SIR values revealed high microbial dormancy under saline stress. Enzyme assays indicated suppressed metabolic activity in high-salt environments, particularly in soils with the lowest pH and highest EC values. Metagenomic analysis revealed variations in alpha and beta diversity across the three soil types, reflecting salinity-induced shifts in microbial community structure and function. These findings highlight the ecological consequences of salinity on soil microbial dynamics and suggest that metagenomic approaches can offer valuable insights for managing saline-affected ecosystems.

Keywords

Soil bacteriome, Soil respiration, Enzymes, Halotolerant bacteria, 16S rRNA sequencing

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