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The experiment was to study the enrichment ability of zinc ions in pig derived Clostridium butyricum JBH-1 strain. The single factor test was used to determine the mass concentration of zinc ions, the time of zinc addition, the amount of inoculation, culture time, types of carbon and nitrogen sources of Clostridium butyricum JBH-1 strain, which affected the zinc enrichment performance of JBH-1 strain. The optimal amount of carbon and nitrogen sources and other fermentation conditions were further optimized by orthogonal experiments. Under the optimized fermentation conditions, a 50 L ferment simulation experiment was conducted to evaluate the zinc enrichment performance of JBH-1 strain. The results showed that the optimal fermentation conditions for zinc enrichment of Clostridium butyricum JBH-1 strain were as follows: Zinc ion mass concentration 250 mg/L, zinc addition time 12 h after culture, JBH-1 strain inoculated 10%, culture time 18 h, sucrose addition 25 g/L, yeast extract powder addition 20 g/L, ammonium chloride addition 2 g/L. The results of simulated fermenter test under the optimal fermentation condition showed that the body weight of JBH-1 strain was 50.75 g, the unit body zinc enrichment was 139.66 mg/g, the zinc enrichment rate was 82.57%, and the zinc probability was 12.60%. The study indicates that comprehensive analysis of zinc concentration, zinc concentration rate and zinc organic rate, Clostridium butyricum JBH-1 strain can be used as a reserve strain of microbial organic zinc preparation for livestock and poultry. [ABSTRACT FROM AUTHOR]

In order to improve the yield of bacteria and thioseterase, the fermentation process of Bacillus amyloliquefaciens H6 was screened and optimized. The nutrient requirements and fermentation conditions of Bacillus amyloliquefaciens H6 were optimized by response surface methodology with viable bacteria count and spore count as indexes. Meanwhile, the mRNA expression level and the recombinant protein activity of thioesterase were also evaluated. The results showed that the optimum carbon source, nitrogen source and inorganic salt screened by single factor experiment were soluble starch, yeast extract powder and MgSO4 respectively. The soluble starch concentration, yeast leaching concentration and fermentation time were the key factors of fermentation. The optimal parameters of culture medium and fermentation process were 32.16 g/L soluble starch, 16.27 g/L yeast powder, 10.00 g/L MgSO4, the fermentation time was 39.28 h, the initial pH was 5.0, the inoculation amount was 1%, the rotation speed was 200 r/min, and the fermentation temperature was 37 ℃. The biological yield of Bacillus amyloliquefaciens H6 reached 6.33×109 CFU/mL by shaking flask and 1.09 × 1010 CFU/mL by 50 L fermenter. The fermentation process of Bacillus amyloliquefaciens H6 was optimized by response surface optimization. Compared with the initial culture- medium, the fermentation level was significantly increased (P< 0.05), and the thioesterase activity was significantly increased (P<0.05). [ABSTRACT FROM AUTHOR]

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