Bacillus velezensis D-1 as well as preparation and application thereof

[0024] (1) Isolation of Bacillus in soil

[0025] Bacillus was isolated from the tested soil sample (healthy tea tree rhizosphere soil in Wuyi Mountain Tea Seedling Cooperation Base, Nanping City, Fujian Province, China) by dilution coating method. Take 10.0 g of the sterilized and air-dried test soil and put it into a conical flask containing 90 mL of sterile water, mix well, and put the diluted solution in a water bath at 85 °C for 30 min. Dilute to 10 with sterile water -3 、10 -4 、10 -5 、10 -6 Wait for different concentrations of bacterial solution, draw 100 μL of bacterial solution and spread it evenly on the NA plate, place it in a constant temperature incubator at 30°C for 24 hours in the dark, and pick a single colony with obvious differences in colony shape to transfer and purify, and the purified strains are stored in 4 ℃ refrigerator for later use.

[0026] (2) Screening of antagonistic strains and observation of antibacterial morphology against target bacteria

[0044] (1) Determination of the antagonistic activity of strain D-1 against three kinds of taro dry rot pathogens

[0045] Using the plate confrontation method, the purified Bacillus D-1 was inoculated in NA liquid medium before the experiment, and cultured in a shaker at 28°C and 180rpm for 12h to obtain OD 600 2.0 bio-control bacteria solution. Use a sterile puncher with a diameter of 5 mm to punch out the edge of the pathogenic bacteria and inoculate it in the center of the PDA plate. Spot 1 μL of biocontrol bacteria solution at a distance of 3 cm from the center of the plate, and use 1 μL of sterile water as a control. Repeat 3 times for each treatment . After inoculation, they were cultured in a constant temperature incubator at 30°C for 6 days. Measure control bacterium colony diameter and handle bacterium colony diameter with cross method, calculate its result of antibacterial rate as table 2 and Figure 6 shown.

[0046] Table 2 Antibacterial effect of strain D-1 on t