Characterization of Rhizobacteria for Sustainable Agriculture and Biofertilizer Development

Abstract

Okra (Abelmoschus esculentus L.) is recognized as one of the most nutritionally and economically significant vegetable crops cultivated extensively across tropical and subtropical regions. Its pods are enriched with vitamins, minerals, dietary fiber, and mucilage, making it a vital component of food security strategies in many developing countries where malnutrition and dietary deficiencies remain pressing challenges. Despite its importance, okra productivity is frequently constrained by multiple factors, including nutrient deficiencies, pest infestations, and abiotic stresses such as drought, salinity, and erratic rainfall patterns. These limitations have prompted the search for sustainable solutions that can enhance crop yield while maintaining soil health. Plant growth‑promoting rhizobacteria (PGPR), which inhabit the rhizosphere, have emerged as promising eco‑friendly alternatives to chemical fertilizers and pesticides. PGPR are known to fix atmospheric nitrogen, solubilize phosphorus and zinc, produce phytohormones such as indole‑3‑acetic acid, and secrete metabolites that suppress phytopathogens. Their multifunctional roles not only improve nutrient availability but also strengthen plant tolerance to environmental stressors. In the present study, five bacterial isolates (MH01, MH03, MH04, MH05, MH06) were characterized for their biochemical traits to evaluate their potential as PGPR candidates for okra cultivation. A series of enzymatic assays revealed strong amylase and cellulase activity in strain MH04, highlighting its capacity to degrade complex carbohydrates and contribute to nutrient cycling. Protease production was most pronounced in MH03, suggesting its role in protein turnover and nitrogen mineralization. Phosphate solubilization was highest in MH05, while zinc solubilization was most effective in  MH01, indicating their importance in mobilizing essential macronutrients and micronutrients. Catalase activity was consistently positive across all isolates, reflecting their resilience under oxidative stress conditions. In addition, exopolysaccharide production and ammonia release were observed in several strains, further emphasizing their functional diversity and potential contributions to soil aggregation, nutrient enrichment, and stress tolerance.Collectively, these findings demonstrate that the isolates possess complementary biochemical traits that can be harnessed in combination as biofertilizers and biocontrol agents. Their application in okra cultivation could reduce reliance on synthetic inputs, improve soil fertility, and enhance crop yield under diverse environmental conditions. This study provides valuable insights into the functional diversity of okra‑associated rhizobacteria and highlights their potential role in advancing sustainable agriculture.