Isolation and Identification of Azotobacter chroococcum Strain and Measuring Microbial Respiration in Saline Soil | ||
| Alexandria Science Exchange Journal | ||
| Article 4, Volume 46, Issue 4, December 2025, Pages 897-907 PDF (381.59 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/asejaiqjsae.2025.465129 | ||
| Author | ||
| Azza Massoud | ||
| Faculty of Agriculture, Alexandria University, El-Shatbi, Alexandria, Egypt. | ||
| Abstract | ||
| Free-living nitrogen-fixing Azotobacter bacteria are beneficial microorganisms that produce phytohormones, contributing to soil fertility and plant growth. It is well known that soil salinity causes significant disturbances in microbial ecosystems, affecting the biological functions of beneficial bacteria. Saline conditions, particularly high concentrations of sodium chloride (NaCl), can inhibit the growth and metabolic activity of these bacteria. This study investigates the viability and activity of Azotobacter in saline soils. It evaluates soil respiration—measured by carbon dioxide (CO2) emission—as a key indicator of microbial activity under high soil salinity. By isolating and characterizing Azotobacter strains from El-Moghraa soil, adding them to highly saline soils, and measuring their microbial activity, we identified strains that can withstand harsh soil salinity conditions. The results demonstrated the biological activity of Azotobacter bacteria in the soil, highlighting their potential for use as biofertilizers in saline agricultural systems. This research serves as a comprehensive evaluation of the role of a Azotobacter chroococcum strain, whose identity was confirmed through 16S rRNA gene sequencing, in improving the health of saline soil. The results clearly show that introducing this bacterium increases soil respiration even under high salinity conditions (EC = 14 dS/m), confirming its significant salt tolerance. Importantly, the addition of organic matter in the form of vermicompost significantly enhanced this effect, indicating a synergistic role. Vermicompost provides a source of carbon and nutrients, in addition to its role in mitigating the osmotic and ionic stress caused by salinity, thereby creating a protected microenvironment suitable for the microbes to flourish. This study presents a strong, evidence-based strategy for the sustainable management of soil in salinity-affected regions, offering a promising and eco-friendly alternative to traditional chemical inputs in agriculture. | ||
| Keywords | ||
| Azotobacter; saline soil; soil respiration; sodium chloride (NaCl); microbial activity; carbon dioxide (CO2) emission; biofertilizers | ||
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