Survey and Morphological, Biochemical and Molecular Characterization of Bacillus Isolates from Brinjal (Solanum melongena L.) Rhizosphere Soils of Tamil Nadu and Andhra Pradesh, India

Diseases caused by soil borne pathogen including Fusarium spp. significantly constrain brinjal (Solanum melongena L.) productivity, highlighting the need for sustainable, eco-friendly disease management strategies. The present study aimed to survey, isolate, and characterize Bacillus spp. from the brinjal rhizosphere across Tamil Nadu and Andhra Pradesh, India. A systematic survey conducted during 2023–2024 resulted in the isolation of twenty Bacillus isolates (AUBI-1 to AUBI-20). The isolates were characterized based on morphological and biochemical traits. All isolates were Gram-positive and exhibited variability in siderophore production, starch hydrolysis, catalase activity, citrate utilization, and nitrate reduction, while all were negative for chitinase production and methyl red test. Based on superior morphological and biochemical traits, isolate AUBI-14 was selected for molecular identification. 16S rRNA gene sequencing confirmed AUBI-14 as B. subtilis (GenBank accession number: PX737071.1). The findings highlight the diversity of Bacillus populations in brinjal rhizosphere soils and provide a foundation for future evaluation of promising isolates for sustainable disease management in brinjal cultivation.