Biological Control Of Bacillus Subtilis BS05 Against Wheat Sharp Eyespot

Wheat sharp eyespot is a kind of soil borne fungal disease caused by Rhizoctonia cerealis and Rhizoctonia solani.The disease can seriously affect the quality and yield of wheat.At present,wheat variety grown in China have not been completely immune to wheat sharp eyespot.We mainly use chemical agents to control wheat sharp eyespot,and chemical agents pollute the environment,and will have a certain effect on wheat yield.Therefore,the use of biological control bacteria which is environmentally friendly to control wheat sharp eyespot has important significance.In this study,bacillus subtilis BS05,which had antagonistic effect on wheat grain blight,was used in this study to study its colonization law in wheat by using rifampicin and streptomycin labeling method.Through the indoor potted experiment,we studied the effect of preventing and promoting the disease of wheat and the mechanism of preventing disease,and optimized the composition and culture conditions of fermentation medium by using the combination of single factor experiment and orthogonal experimental design.The experimental results are as follows:?1?we get marked BS05^sr by antibiotics induce original strain BS05,which can grouth on the NA medium containing 300?g/mL streptomycin and 100?g/mL rifampicin.Compared with the original strain,BS05^sr bacterial colony growth curve,biofilm formation ability,antagonistic effect on pathogenic bacteria,which are no significant difference with the original strain.?2?we studied the growth of the strain BS05 on wheat by the inoculation of roots and seeded strain BS05.In the two treatments,the colonization of strain BS05in wheat gradually increased,then gradually decreased after reaching the peak,and the strain BS05 could still be detected in the 30th day.In the root treatment,the colonization of the seventh day is the largest,which is 1.20×10⁵CFU/g in root,1.02×10⁴CFU/g in stems,5.91×10³ CFU/g in leaf.In the seed treatment,the colonization of the tenth day is the largest,which is 8.95×10⁴ CFU/g in root,2.98×10⁴CFU/g in stems,3.87×10³ CFU/g in leaf.?3?Bacterial strain BS05 could induce PPO,POD and PAL activity in wheat.In strain BS05 suspension treatment,the enzyme activity of PPO,POD and PAL in wheat increased by 21.60%,19.92%,28.87%.In bacterial fermentation broth treatment,The activity of PPO,POD and PAL in wheat increased by 20.61%,18.43%and 24.47%.?4?The strain BS05 has a positive effect on the growth of wheat.After the strain BS05 was treated,the height of the wheat plant increased by 5.49%,the fresh weight increased by 27.52%,and the dry weight increased by 28.95%.Potted experiments showed that strain BS05 had a certain effect on wheat sharp eyespot,and the control effect was 62.77%.?5?Strain BS05 optimal fermentation medium composition of 1.5%sucrose,1.0%of beef extract and 0.10%KH₂PO₄,and the optimal culture conditions for the medium initial pH7,culture temperature 30?,rotating speed of 150 r/min,inoculation amount 3%.The activity of antibacterial active substances could be increased under the optimal fermentation medium and optimum culture.