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<p>Red lateritic soils, which are in the semiarid regions of West Bengal’s Rarh tract in India, present harsh conditions for agriculture because of their high acidity, low organic matter, and poor nitrogen availability. To address these limitations, we explored native microbial communities with a focus on stress-resistant, endospore-forming diazotrophs. Soil samples collected from agricultural fields in the Bankura district were analysed for their physicochemical properties and microbial potential. Using progressive heat-shock enrichment, nine strains were isolated–six from heat-treated soils and three from non-heat-treated soils. Functional assays revealed strong nitrogen-fixing activity (2.1–8.4&#xa0;mg N/g sugar consumed), confirmed by acetylene reduction, alongside production of indole-3-acetic acid (up to 10.92&#xa0;µg/mL) and phosphate solubilization (4.84–18.04%) which are key traits of plant growth promoting (PGP) activity in degraded soils. Molecular identification through 16&#xa0;S rDNA sequencing revealed close relationships with species of Bacillus and Priestia, including <i>B. rhizoplanae</i>, <i>P. megaterium</i> and notably <i>B. gaemokensis</i> and <i>P. abyssalis</i>. This study provides the first experimental evidence of diazotrophic activity in <i>Priestia abyssalis</i> and <i>Bacillus gaemokensis</i> revealing two previously unrecognized members of the nitrogen-fixing microbial community. Seasonal monitoring showed monsoon soil pH dropped to 4.3–4.8 because of cation leaching. Unlike <i>Azotobacter</i>, our endospore-forming isolates survived acidic stress via sporulation and regained normal growth upon transfer to neutral pH. These findings underscore the potential of harnessing native, endospore-forming diazotrophs as bioinoculants for improving soil health in nutrient-poor, climate-stressed regions. Their natural adaptability makes them promising agents for sustainable agriculture, reducing their reliance on chemical fertilizers and supporting resilient farming systems.</p>

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Stress-resilient endospore-forming diazotrophs from red lateritic soils of India: functional profiling and first evidence of Priestia abyssalis and Bacillus gaemokensis as nitrogen-fixers with multifunctional PGPR traits

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Jisan Sarwar,
  • Shilajit Barua

摘要

Red lateritic soils, which are in the semiarid regions of West Bengal’s Rarh tract in India, present harsh conditions for agriculture because of their high acidity, low organic matter, and poor nitrogen availability. To address these limitations, we explored native microbial communities with a focus on stress-resistant, endospore-forming diazotrophs. Soil samples collected from agricultural fields in the Bankura district were analysed for their physicochemical properties and microbial potential. Using progressive heat-shock enrichment, nine strains were isolated–six from heat-treated soils and three from non-heat-treated soils. Functional assays revealed strong nitrogen-fixing activity (2.1–8.4 mg N/g sugar consumed), confirmed by acetylene reduction, alongside production of indole-3-acetic acid (up to 10.92 µg/mL) and phosphate solubilization (4.84–18.04%) which are key traits of plant growth promoting (PGP) activity in degraded soils. Molecular identification through 16 S rDNA sequencing revealed close relationships with species of Bacillus and Priestia, including B. rhizoplanae, P. megaterium and notably B. gaemokensis and P. abyssalis. This study provides the first experimental evidence of diazotrophic activity in Priestia abyssalis and Bacillus gaemokensis revealing two previously unrecognized members of the nitrogen-fixing microbial community. Seasonal monitoring showed monsoon soil pH dropped to 4.3–4.8 because of cation leaching. Unlike Azotobacter, our endospore-forming isolates survived acidic stress via sporulation and regained normal growth upon transfer to neutral pH. These findings underscore the potential of harnessing native, endospore-forming diazotrophs as bioinoculants for improving soil health in nutrient-poor, climate-stressed regions. Their natural adaptability makes them promising agents for sustainable agriculture, reducing their reliance on chemical fertilizers and supporting resilient farming systems.