Stability test of ferment filtrate by Arthrobacter YB6 strain and its control effect on Ralstonia solanacearum

Arthrobacter YB6 strain is an antagonistic bacterium against Ralstonia solanacearum. In the stability test, the ferment filtrat was sensitive to heat, acid-alkali and protease K, it had no antibacterial activity when the temperature was above 60℃, the antibacterial activity would decrease significantly under the condition of strong acid-alkali or the concentration of protease K over 1.5 mg/mL. However,the ferment filtrat had strong stability against light and UV. The antibacterial activity was still stable under the condition of UV irradiation for 5 h or 35 000 L light. The ferment filtrat had wide antibacterial spectrum, and had inhibiting effect against 8 pathogen in the test. It had the best inhibiting effect against Ustilago scitaminea Syd. and Fusarium graminearum, the bacteriostatic rate achieved 88.6% and 80.2%,respectively. The inhibition activity against R. solanacearum by the dipping inoculum method was the best in pot experiments and its biocontrol rate reached 65.0%.