Study On Fermentation Kinetics Of Brevibacillus Brevis Ch2-22 And Preparation Of Water Dispresible Granule

We screened the brevibacillus brevis ch2-22 from soil.The results showed that the 3kDa gramicidin is the only antibacterial substance which the strain could produce.It has the broad-spectrum antifungal activity and can effectively inhibit the pathogenic fungi such as Botrytis cinerea,anthracnose pathogen,leaf blight pathogen and so on.The application test results showed that ch2-22 fermentation liquid had a good control effect on cucumber gray mold and cotton Fusarium wilt,and had a significant effect on plant growth.In this study,the fermentation process of Bacillus subtilis was optimized,and the kinetic model was established,and then the water dispersible granules?WDG?were prepared.1.The basic components of fermentation medium were determined by single factor experiment,and the response surface design was optimized on the basis of single factor experiment.The starch,soybean powder and sucrose are vital factors affecting the spore production of marine,which was determined by the design of Plackett-Burman.The optimized fermentation medium is starch 35.05 g/L,soybean powder 26.08 g/L,sucrose 10g/L,fish meal 5 g/L,NaCl 1 g/L,MgSO₄ 0.3 g/L,?NH₄?₂SO₄ 3 g/L,MnSO₄ 0.1 g/L,K₂HPO₄ 3 g/L,yeast extract 1 g/L,CaCO₃ 2 g/L.Incubation temperature 32?,shaking speed 180 r/min,liquid volume 100 mL in 500 mL,inoculum size 4%,initial pH 7.0,culture time 45 h.The colony-forming units per milliliter were improved from 1.6×10⁹ to8.1×10⁹ after optimization,and the spore concentration is increased by 3.7 times.The broth titer reached 2335 IU/mL,which increased by 94.5%,and higher than strain of the same kind.2.The bath fermentation is conducted in 5 L fermentor on the basis of the optimized fermentation medium and culture conditions,determination of mycelium concentration,sugar concentration and fermentation liquid antibacterial activity,established and verified brevibacillusbrevs ch2-22 batch fermentation kinetics model,the results showed that the dynamic model can reflect the the fermentation process.The kinetic model of cell growth:???Kinetic model of product synthesis:???kinetics model of Substrate consumption:???3.The best formula of 40%of the original water dispersible granules was determined by screening the Bacillus pumilus ch2-22 strain with water dispersible granule additives:40%of Bacillus pumilus powder,wood Sodium sulfonate 20%,sodium carboxymethyl cellulose 1.5%,sodium alginate 25%,?-cyclodextrin 5%,kaolin 8.5%.The dosage of the water dispersible granules was 1.9×10¹⁰ cfu/g,the disintegration time was 170 s,and the suspension rate was 85%.And spore survival rate reach 90%after accelerated storage test.