Induction of Endophytic Bacteria to Enhance Intracellular Immunity of Arabica Coffee (Coffea arabica L.) Infected with Fusarium sp. in vitro

This study aimed to isolate and characterize endophytic bacteria from the roots of Arabica coffee (Coffea arabica L.), investigate their growth patterns, and evaluate their antagonistic activity against the pathogenic fungus Fusarium sp. Through surface sterilization and subsequent cultivation on Nutrient Agar, six distinct endophytic bacterial isolates were obtained, exhibiting diverse colony morphologies ranging from circular to irregular, and colors from white to cream or yellowish. Antagonism assays indicated varying degrees of inhibitory effects against Fusarium sp.: Sp2At produced the largest inhibition zone with an average of 17.9 mm, followed by Sp3At at 16.86 mm, while Sp4At and Sp6At showed smaller zones of 6.16 mm and 6.9 mm, respectively. Furthermore, the highest indole-3-acetic acid (IAA) production was detected at pH 7.5 with 291.64 ppm, whereas pH 6.5 resulted in the lowest IAA production at 281.04 ppm after 72 hours of incubation. These results suggest the potential of these isolates to promote plant growth through phytohormonal pathways. Keywords: Antagonist, Coffea arabica L, Colony morphology, Endophytic bacteria, Fusarium sp.