Nodule bacteria and cyanobacterial symbionts: Biological drivers of sustainable crop production and healthy nutrition

Abstract

Background: Chemical fertilizers negatively impact soil health and biodiversity, highlighting the urgent need for sustainable biological alternatives. Nodule-forming bacteria are well recognized for their ability to establish symbiotic associations with leguminous crops, enabling biological nitrogen fixation and promoting environmentally sustainable agriculture. At the same time, legumes represent a cornerstone of functional food science, providing high-quality proteins, bioactive compounds, and micronutrients essential for human health.

Objective: This study aimed to evaluate the effects of co-inoculating legume crops with native strains of nodule bacteria and cyanobacteria on plant growth in humus-deficient soils, yield performance, grain nutritional quality, and their potential contribution to functional food development.

Methods: Field trials were conducted using pea, soybean, and peanut crops inoculated with microbial consortia comprising symbiotic nodule bacteria (Rhizobium leguminosarum, Bradyrhizobium arachidis, B. japonicum) and cyanobacteria (Nostoc PCC 7807, Arthrospira platensis). Key agronomic parameters, including biometric traits, pod and seed weight, nodulation efficiency, grain protein content, and yield components, were measured and subjected to statistical analysis under humus-deficient soil conditions.

Results: Co-inoculation significantly enhanced plant performance across all tested crops. Peanut pod weight increased by up to 120%, while soybean nodulation improved by 60% compared to the uninoculated control. Grain protein content increased by 3–7%, with improved amino acid balance, directly strengthening the functional food value of legumes. Total yield rose by as much as 67%, highlighting the strong synergistic potential of microbial consortia for sustainable crop production and nutritionally enriched food sources.

Novelty: This study presents a novel biofertilizer formulation combining four functionally distinct bacterial taxa with nitrogen-fixing and nutrient-mobilizing capabilities. In addition to symbiotic nodule bacteria, the formulation includes free-living Azotobacter, phosphate-solubilizing bacilli, and two cyanobacterial species (Arthrospira platensis, Nostoc sp.), linking soil microbiology innovations with functional food science by enhancing protein density and nutritional quality in legumes.

Conclusion: The results confirm that synergistic interactions between cyanobacteria and nodule bacteria significantly enhance legume productivity, grain quality, and functional food potential. The developed biofertilizer based on nitrogen-fixing, phosphate-solubilizing, and photosynthetic microbes proved effective in improving yields of soybean, peanut, and pea under low-humus soil conditions, offering a sustainable strategy to support agroecology, food security, and the production of health-promoting plant-based foods.

Keywords: nodule bacteria, cyanobacteria, symbiosis, legumes, humus-deficient soils, sustainable agroecology and functional foods, protein enrichment, healthy nutrition