Inhibition To Monilinia Fructicola And Preservation Of Peach Fruits By Bacillus Licheniformis W10

Peach brown rot (Monilinia fructicola) is a serious disease during peach fruit growth and postharvest in China. The inhibition to the peach brown rot pathogen, the preservation of peach fruits by Bacillus licheniformis W10 and its synergistic effects with fungicides were studied in order to provide the basis for the biological control of this disease.The results showed that the bacterial suspension, culture filtrate and antifungal protein from W10 exhibited obvious inhibition on the mycelial growth, sporulation, conidial germination and germ-tube elongation of M. fructicola. The culture filtrate diluted 5 times and the antifungal protein with 1.333 mg/mL had 85.2% and 100% inhibiting rates respectively toward the mycelial growth. The culture filtrate diluted 2 times and the antifungal protein with 6.666 mg/mL had 84.0% and 100% inhibiting rates respectively on the sporulation. The bacterial suspension of 1 × 10 cfu/mL and the antifungal protein with 1.333 mg/mL could completely inhibit the conidial germination and germ-tube elongation. The culture filtrate diluted 2 times and the antifungal protein with 0.013 mg/mL had above 80% inhibiting rate to the conidial germination and germ-tube elongation. Moreover, the bacterial suspension, culture filtrate and antifungal protein were demonstrated to have a destructive effect on the hyphal shape and structure of the pathgen, with hyphal cell distortion, tumescence, protoplasm leakage, cell wall breakage, and hyphal rupture.When peach in storage were treated by W10 bacterial suspension and its antifungal protein, the fruit rot caused by M. fructicola was better controlled, whose effects were associated with the concentration of the bacterial suspension and the antifungal protein, the environmental conditions such as temperature and relative humidity in storage as well calcium addition. In general, the better control effects, the higher concentration. The bacterial suspension with 1010 cfu/mL could 100% inhibit the fruit rot caused by M. fructicola and postpone the rot for 9 d. The the inhibiting rate of the antifungal protein with 0.3 mg/mL-3.0 mg/mL was above 40% and the fruit rot was put off for 1-3 d. Inoculated with bacterial suspension and antifungal protein prior to the pathogen had a better biocontrol effect on peach brown rot, and there was no no difference among the effects of 1 d,3 d and 5 d ahead of the inoculation of the bacterial suspension treatments. The environmental conditions such as temperature and relative humidity in storage could affect biocontrol effects of the bacterial suspension and the antifungal protein. The influence of environment conditions on the effect of antifungal protein was less than on that of the bacterial suspension. The lower temperature (4℃) and lower relative humidity (RH 70-75%) were favorable to prevent peach fruit rot by the treatment of the bacterial suspension and its antifungal protein. Moreover, The bacterial suspension and antifungal protein added with 0.1% Ca(NO3)2 could enhance the biocontrol effect, and obviously put off occurrence of the fruit rot.W10 bacterial suspension and its antifungal protein could not only inhibit peach fruit rot, but also have no influence on fruit quality such as fruit flesh pigment, fruit firmness, soluble solids content and weight loss. Therefore, B. licheniformis W10 is a potential factor for the biocontrol of peach brown rot.Toxicity test showed that carbendazim, procymidone and diniconazole could effectively inhibit the mycelial growth of M.fructicola. When W10 bacterial suspension was mixed with the fungicides mentioned above, the synergistic ratio (SR) value of the bacterial suspension and diniconazole with the mixed ratio 1:2 was 2.57, having additive toxicity effect. The mixtures the antifungal protein and carbendazim with ratios of 1:1,10:1 and 100:1 could obviously increase the toxicity, with SR value of above 4. When the antifungal protein was mixed with procymidone with ratio of 100:1, SR value was 3.86, with additive toxicity effect. Therefore, B. licheniformis W10 could be used for the biocontrol of peach brown rot, or mixed with some fungicides and used for the control of the disease.