Study On Separation And Inhibiting Ability Of Bacillus Subtilis21

There are a lot of beneficial microorganisms in the soil, take the purpose of controling plantdiseases, five antagonistic Bacillus spp was screened from soil. The cultural conditions andantibacterial activity of B. subtilis21strain, one of these five strains, were studied.Using the dural culture method, taking eight kinds of plant pathogens as materials, theinhibitory spectrums of these five selected strains were determined. The results showed the higheffective and broad spectrums of these five strains on antagonism activity. The antagonisticBacillus sp21was defined as B. subtilis by the methods of morphology and16S rDNAsequencing. Taking Biploars carbonum as indicator pathogens, carbon, nitrogen source and NaClon the antagonism activity and the the effect of different fermentation parameters by pH,temperature, rotating speed and inoculation amount on antagonism activity of this strain were alloptimized by the method of single and orthogonal factor design. The results show that: theinhibitory ability under the cultural condition of soluble starch, tryptone and no NaCl wasoptimal, the inhibitory ability under the fermentation of pH5, temperature as35°C, inoculationamount as4%and rotating speed as160r/min was optimal.The effect of different concentrations of B. subtilis fermentation on conidia germination andmycelial growth of B. carbonum were studied, the result showed: on spore germinationexperiments, spore germination rate of B. carbonum was decreased treated by B. subtilisfermentation. The spores treated by fermentation were teratogenic and could not developproperly. Measuring the stability of the B. subtilis fermentation showed: the antagonistic abilitywas relative stable to heat, pH, proteinase K and alkaline protease, but unstable to trypsin andpapain.Antibacterial active substance of the B. subtilis fermentation was preliminary separated, usingthe methods of ammonium sulfate precipitation. The results showed that: the active substancecould be precipitated by ammonium sulfate; the strongest inhibition activity was under theammonium sulfate condition of60%. The activity material of B. subtilis fermentation wasconfirmed as protein initially. The effect of B. subtilis fermentation on seed germination andenzyme activity during seed germination was found by Maize materials: the germination rate andseed enzyme activities of soybean seeds were changed differently treated by differentconcentrations of B. subtilis fermentation. The seed germination was promoted by the concentration of40%fermentation, and its rate was up to80.3%; The enzymatic assays resultsshowed that: antioxidant activity was different under different concentrations of B. subtilisfermentation, the POD, CAT and SOD enzyme activities were76.8U,3.54U and764U.