The invention provides a biocontrol
bacterial strain for preventing and treating
plant diseases and its
bacterial agent, belonging to the field of biological control. The strains used are
Gram-negative
bacteria, identified as
Lysobacter enzymogenes, and the strain code is OH11. Strain OH11 has no flagella but has slippage, can produce various
extracellular hydrolytic enzymes including
chitinase, β-1,3-
glucanase and
protease, and can effectively inhibit the growth of fungi and
bacteria. The antibacterial zone diameters of strain OH11 against
Sclerotinia sclerotiorum and
Phytophthora capsici were both greater than 22.0 mm; the
antagonism against potato ring rot was stronger, and the
diameter of the
inhibition zone reached 50 mm. The OH11 strain was inoculated into the seed tank, cultivated to the
logarithmic growth phase, and the seed liquid was connected to the production tank for cultivation. The medium used in the production tank was the same as that of the seed tank. The liquid
fermentation adopts aerobic
submerged fermentation and fed-batch process, the dissolved
oxygen is 15%-20%, the
fermentation temperature is 30°C, the
fermentation time is 72h, and the initial pH value is 7.5. After the fermentation is completed, the culture solution is taken out of the tank and directly packed into liquid dosage forms with
plastic packaging barrels or packaging bottles, or subpackaged into
solid dosage forms with
peat adsorption packaging bags. The biocontrol strain OH11 can effectively control
plant pathogenic fungi,
bacteria, nematodes and other diseases, and the overall
control effect is 50%-70%. In the
greenhouse pot experiment, the control effects of OH11 on pepper
blight and tomato
bacterial wilt reached 83.6% and 86.4%, respectively. Strain OH11 has the characteristics of broad antibacterial spectrum,
high activity, and
environmental safety. In today's serious
pesticide pollution, zymolysobacterium and its
bacterial agent will be a good substitute.