To understand the endophytic bacteria of Aphidius gifuensis[Bacillus pumilus,Exiguobacterium sibiricum,Bacillus cereus(yellow and white colonies)],the effects of these bacteria on Fusarium oxysporum and Ralstonia solanacearum were studied.The inhibitory activities of the four endophytic bacteria against F.oxysporum and R.solanacearum were examined using the solid agar method.The results showed that in the laboratory bacteriostasis test,F.oxysporum of tobacco was not significantly inhibited by B.pumilus and B.cereus(yellow colony).However,F.oxysporum of tobacco was significantly inhibited by E.sibiricum.When the E.sibiricum concentration was 7.0×106 cfu·mL-1,the inhibition was strongest and the F.oxysporum inhibition rate was 28.27%.When the concentration was 7.0×104 cfu·mL-1,the promotion effect was the highest,and the inhibitory rate was-15.81%.The inhibition rates of F.oxysporum of tobacco at other concentrations were in between-2.89%and 21.73%.Control effects of E.sibiricum on F.fusarium of tobacco were significantly stronger at 7.0×105 cfu·mL-1;the rates were 32.21%and 27.56%at 7 and 14 d,respectively.Different concentrations of B.cereus(white colony)had significant inhibitory effects on F.oxysporum.As the concentration increased,the colony diameter and inhibition rate gradually decreased and increased,respectively.The inhibition effect was strongest and its rate was 21.74%when the concentration was 3.4×107 cfu·mL-1.The inhibition rates of other concentrations were between 9.57%and 17.39%.The four endophytic bacteria had significant effects on the bacteriostatic zone diameter of R.solanacearum.The inhibition effects by B.pumilus and B.cereus(white colony)were the strongest 12 h after treatment.The antibacterial zone diameters were 2.02 and 2.22 mm when the concentrations were 6.9×106 and 3.4×105 cfu·mL-1,respectively.The inhibition effects by E.sibiricum and B.cereus(yellow colony)were strongest 24 h after treatment.The antibacterial zone diameters were 1.59 and 1.67 mm when the concentration was 7.0×103 and 1.5×108 cfu·mL-1,respectively.Control effects of B.cereus(white colony)on R.solanacearum of tobacco were significantly stronger at 3.4×105 cfu·mL-1;the inhibition rates were 56.11%and 39.78%at 7 and 14 d,respectively.Thus,the results of this study can provide scientific reference for using endophytic bacteria to control F.oxysporum root rot and bacterial wilt,and the development of bacteriostatic agents against pathogens.
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