biostudies-literatureUnknown10(38)Thanapaul NBRhizobium bacteria convert atmospheric nitrogen into ammonia that leguminous plants can use as a nitrogen source, reducing the need for synthetic nitrogen fertilizers. <i>Bradyrhizobium</i> sp. SUTN9-2 is an effective biofertilizer suitable for legume-rice rotational cropping systems that promotes growth and stress resistance. Deploying this biofertilizer for sustainable agriculture requires a rapid and cost-effective method for monitoring bacterial concentrations in the soil. In this work, we developed and optimized an antibody-based biosensor for the detection of <i>Bradyrhizobium</i> sp. SUTN9-2 via electrochemical impedance spectroscopy (EIS). The immunosensor was fabricated by covalently immobilizing a recombinant antibody specific to SUTN9-2 onto a dithiobis-succinimidyl propionate (DSP) self-assembled monolayer on a gold electrode. The resulting immunosensor effectively captures <i>Bradyrhizobium</i> sp. SUTN9-2 cells are present in samples, leading to changes in electrode impedance. The immunosensor demonstrated excellent specificity, a wide linear detection range of 1 × 10³ to 1 × 10⁷ CFU/mL (<i>R</i> ² = 0.992), and a limit of detection approaching the single-cell detection limit. The compatibility of the sensor with a soil sample was also demonstrated. The platform holds great promise for the portable monitoring of soil biofertilizer levels and could also be adapted to other strains of interest.ACS omega44489-44498https://www.ebi.ac.uk/biostudies/studies/S-EPMC12489705biostudies-literatureSensitive Detection of Nitrogen-Fixing Soil Bacteria by Impedimetric Immunosensing.PMC12489705Yamabhai MPinyou PBlay VThanapaul NBBista STittabutr PfalseSensitive Detection of Nitrogen-Fixing Soil Bacteria by Impedimetric Immunosensing.Rhizobium bacteria convert atmospheric nitrogen into ammonia that leguminous plants can use as a nitrogen source, reducing the need for synthetic nitrogen fertilizers. <i>Bradyrhizobium</i> sp. SUTN9-2 is an effective biofertilizer suitable for legume-rice rotational cropping systems that promotes growth and stress resistance. Deploying this biofertilizer for sustainable agriculture requires a rapid and cost-effective method for monitoring bacterial concentrations in the soil. In this work, we developed and optimized an antibody-based biosensor for the detection of <i>Bradyrhizobium</i> sp. SUTN9-2 via electrochemical impedance spectroscopy (EIS). The immunosensor was fabricated by covalently immobilizing a recombinant antibody specific to SUTN9-2 onto a dithiobis-succinimidyl propionate (DSP) self-assembled monolayer on a gold electrode. The resulting immunosensor effectively captures <i>Bradyrhizobium</i> sp. SUTN9-2 cells are present in samples, leading to changes in electrode impedance. The immunosensor demonstrated excellent specificity, a wide linear detection range of 1 × 10³ to 1 × 10⁷ CFU/mL (<i>R</i> ² = 0.992), and a limit of detection approaching the single-cell detection limit. The compatibility of the sensor with a soil sample was also demonstrated. The platform holds great promise for the portable monitoring of soil biofertilizer levels and could also be adapted to other strains of interest.2025-01-01T00:00:00Z2025 Sep2026-06-04T05:07:49.319Z2026-05-05T03:12:33.903ZS-EPMC124897054104879810.1021/acsomega.5c06583