MOLECULAR IDENTIFICATION OF MULTI-TRAIT ENDOPHYTIC BACTERIAL ISOLATES ENHANCING MAIZE GROWTH

This study aimed to isolate and characterize bacteria from maize endosphere with potential plant growth-promoting (PGP) properties. Seed samples were analyzed using serial dilution, pour plating, and streak plating to obtain pure bacterial cultures. The isolates underwent biochemical tests, PGP screening, process optimization, molecular identification, and maize seed bioinoculation trials. Morphological analysis showed raised colony elevation in all isolates except C1. C1 and C3 had shining textures, while C2 was dull. All isolates were rod-shaped, occurred in chains, fermented sugars, and tested positive for PGP traits except C2 which is negative for siderophore production. Isolate C1 showed the highest nitrogen fixation zone of 3.0 cm. Quantitative analysis revealed that C3 exhibited nitrogen fixation and zinc solubilization activities of 2.88 and 2.20 µg/mL, respectively. C1 produced 2.18 µg/mL of indole-3-acetic acid (IAA). Both C2 and C3 didn't exhibit enzymatic activity, with Cl recording a high amylase activity of 2.83 U/mL. Isolate C3 responded well to 6 g glucose with highest value 2.05, while C3 showed 2.83 in 3 g yeast extract-supplemented medium. All isolates grew in lead-supplemented media, with no inhibitory effects from other metals. Maximum IAA production of 2.05 µg/mL was recorded in medium with 6 g glucose. Molecular identification confirmed the bacterium as Bacillus Cereus. The isolates were resistant to Amplicox, Zinnacef and Amoxicillin. Bioinoculated maize seeds showed improved growth in maize length in number of root 6.3 cm (in vitro) and showed improved growth in maize length 88.1 cm (in field, and 52.0 cm (greenhouse), compared to un-inoculated. These findings support the potential use of Bacillus Cereus as a bioinoculant to enhance maize growth through multiple PGP mechanisms.