PLANT GROWTH PROMOTING POTENTIAL OF CALIDIFONTIBACILLUS ERZURUMENSIS AS11 ISOLATED FROM GARLIC (ALLIUM SATIVUM L.) AND ITS ANTAGONISTIC ACTIVITY AGAINST ASPERGILLUS NIGER

Abstract

Garlic (Allium sativum L.) is an economically important spice crop affected by black mold disease caused by Aspergillus niger. The present study aimed to isolate and characterize endophytic bacteria from garlic and evaluate their plant growth promoting and biocontrol potential against A. niger. A total of 20 bacterial endophytes were isolated and screened for antagonistic activity using the dual culture assay. Among the isolates, strain AS11 exhibited the highest antifungal activity with 79.33% mycelial growth inhibition and an inhibition zone of 13.00 ± 1.73 mm. Molecular identification based on 16S rRNA gene sequencing identified isolate AS11 as Calidifontibacillus erzurumensis. The isolate exhibited multiple plant growth-promoting traits including indole acetic acid production, ammonia production, biological nitrogen fixation, siderophore production, and phosphate solubilization. Germination and pot experiments demonstrated significant improvement in garlic growth parameters under Calidifontibacillus erzurumensis AS11 treatment and partial protection against pathogen stress. Statistical analysis was performed using Student’s t-test and one-way ANOVA followed by Tukey’s HSD test at p < 0.05 using Python. The findings suggest that C. erzurumensis AS11 possesses strong plant growth promoting and biocontrol potential and may serve as an eco-friendly bioinoculant for sustainable garlic cultivation.