INSTITUTE OF BIO- AND GEOSCIENCES,NSTITUTE OF BIO- AND GEOSCIENCESSTELLA F. VALLE, UNIVERSIDADE FEDERAL DE SÃO CARLOSEPAGRI - AGRICULTURAL RESEARCH AND RURAL EXTENSION COMPANY OF SANTA CATARINAFORSCHUNGSZENTRUM JÜLICH GMBH, INSTITUTE OF BIO- AND GEOSCIENCESJOANA DIAS BRESOLIN, CNPDIAFORSCHUNGSZENTRUM JÜLICH GMBH, INSTITUTE OF BIO- UND GEOSCIENCESFORSCHUNGSZENTRUM JÜLICH GMBH, INSTITUTE OF BIO- UND GEOSCIENCESMARIANGELA HUNGRIA DA CUNHA, CNPSOCAUE RIBEIRO DE OLIVEIRA, CNPDIALUIZ HENRIQUE CAPPARELLI MATTOSO, CNPDIAFORSCHUNGSZENTRUM JÜLICH GMBH, INSTITUTE OF BIO- AND GEOSCIENCES.2026-07-07http://hdl.handle.net/123456789/463040ABSTRACT The microbial inoculation of legumes such as soybeans is crucial for thriving plant growth due to symbiotic nitrogen (N) fixation and biological plant N fertilization. Soybean requires microbial pre-inoculation before sowing using the rhizobia strain Bradyrhizobium japonicum. Peat is typical for this purpose, although not sustainable since it is a finite resource. Here, we propose a straightforwarding route to prepare and apply polyglycerol-citrate polymer (PGC), a biodegradable and fully renewable polymer, as a carrier for Bradyrhizobium japonicum inoculants for soybeans. This novel eco-friendly polymer combines the advantages of a polymeric, water-soluble structure based on biopolymers, which can protect the inoculant cells during the seed inoculation process, with protective properties of glycerol for bacterial cells and the contribution of citric acid for metabolic processes. A greenhouse study was conducted using soybean seeds coated with three different proportions of PGC with B. japonicum planted in a sand substrate free of external interference. Comparative results of N content and δ15N signature in soybean plant parts calculated from the natural abundance method associated with viability tests showed equal or superior symbiotic performance and nitrogen fixation rates to peat-based inoculants, considered the goldstandard carrier for inoculants. It ensured the shelf life of the inoculant formulations, offering convenience for farmers and environmental benefits through reduced fertilization.1 - 9openAccessPolymerSeed-coatingInoculantRhizobiaArtigo de periódico