Morpho-Molecular Characterization of Bacillus spp. Isolated from Different Rice (Oryza sativa L.) Cultivars across Tamil Nadu and Telangana, India

The rice rhizosphere hosts a diverse community of beneficial bacteria with important implications for sustainable crop management. In this study, twenty native Bacillus isolates were isolated from rice-growing regions of Tamil Nadu and Telangana, India, and evaluated through integrated morpho-biochemical and molecular characterization. The isolates exhibited substantial diversity in colony morphology, cellular traits, and biochemical profiles, reflecting their ecological adaptability across different agro-climatic regions. Most isolates were Gram-positive rods and showed variability in key functional traits such as starch hydrolysis, siderophore production, catalase activity, and nitrate reduction, indicating metabolic versatility relevant to rhizosphere competence. Molecular identification of a representative isolate, AUBA-5, using 16S rRNA gene sequencing confirmed its affiliation with the genus Bacillus , with the sequence deposited in GenBank under accession number PX737087.1. Phylogenetic analysis further validated its taxonomic placement within the Bacillus clade. The concordance between phenotypic diversity and molecular confirmation underscores the reliability of the integrated characterization approach. Overall, the study highlights the diversity of native Bacillus spp. associated with rice rhizosphere soils and provides a scientific basis for their future evaluation and utilization in sustainable potential for future evaluation programs.