Biological Control of African Violets Root-Knot Disease by the Used of Extracellular Protease <i>Bacillus</i>

Abstract

The present study explored the efficacy of <em>Bacillus</em> spp. and protease production for biocontrol of the root-knot nematode <em>Meloidogyne javanica</em> in African violet media. Among 100 bacterial isolates from various soils, the highest nematode mortality was observed for treatments with isolate GM-18, which was identified as <em>Bacillus subtilis</em> based on cultural and morphological characteristics and 16S rDNA sequencing analyses. The <em>Bacillus</em> spp. showed nematicidal activity 74.01 to 28.33. Strain GM18 showed the most inhibitor zone in medium containing casein (13 mm) and nematicidal activity in our tests targeting <em>Meloidogyne javanica</em>. The effect of different variables such as time (1-24 h), pH (7- 8.5), and temperature (25- 37 °C) on the protease production was checked. The maximum enzyme production was noted when <em>B. subtilis </em>GM18 was grown on mineral medium and incubated at 31°C for 12 h with initial pH = 8. Three protease inhibitors that had the greatest influence on EDTA were studied. Protease produced by <em>B. subtilis</em> GM18belonged to different groups.