IDENTIFICATION AND ASSESSMENT OF THE ENZYME-BASED, ANTAGONISTIC POTENTIAL OF Bacillus sp. AGAINST Phytophthora palmivora CAUSING GUMMOSIS TRUNK CANKER DISEASE ON JACKFRUIT IN CHO MOI DISTRICT, AN GIANG PROVINCE

Abstract

In recent years, gummosis trunk canker disease caused by Phytophthora palmivora has become a major threat to jackfruit production. In this study, 12 soil samples were collected from jackfruit fields in Cho Moi district, An Giang province, for the isolation, identification and evaluation of enzyme-secreting activity of Bacillus sp. strains with antagonistic potential against Phytophthora palmivora causing gummosis trunk canker disease on jackfruit (Artocarpus heterophyllus) in vitro conditions. The results indicated that four bacterial strains (CM1, CM2, CM3, and CM4) were isolated, exhibiting morphological characteristics typical of Bacillus sp. (round colonies, white to opaque white color, dry wrinkled surface, elevated, serrated edges) and biochemical properties characteristic of Bacillus species. All were gram-positive bacteria, catalase-positive (bubble formation), negative with 3% KOH (no mucous formation) and showed antagonistic activity against the pathogenic fungus. Among them, the strain identified as Bacillus velezensis CM1 exhibited the best antagonistic effect (16.2 - 67.0%) and the strongest production of cellulase (31.2 - 60.0 mm), β-glucanase (37.7 - 63.7 mm), and protease (42.9 - 62.0 mm) from 3 to 9 days after inoculation. Bacillus velezensis CM1 was considered a promising biocontrol agent for managing stem canker disease in jackfruit.