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Investigating the Production of Phytase Enzyme via Bacillus Subtilis and Probiotic Bacteria in an Industrial Culture Medium

Ehterami, Mahla | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58015 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Askaripour, Hossein
  7. Abstract:
  8. This study focuses on the optimization of process conditions and culture medium for the production of phytase enzyme from two bacterial strains, Bacillus subtilis ATCC6633 and Lactobacillus acidophilus DSM17299, for potential use in the animal and poultry feed industry. Initially, optimal culture medium design for enzyme production was conducted using Minitab software and the Central Composite Design (CCD) method. Four variables—temperature, pH, carbon source concentration (wheat bran), and nitrogen source concentration (soybean meal)—were simultaneously investigated. Following data analysis with statistical methods, the optimal environmental conditions and suitable culture medium composition for enhanced phytase production were determined. The results demonstrated that the highest phytase production by Bacillus subtilis occurred under the following conditions: pH 5.5, incubation temperature of 33.8°C, wheat bran concentration of 7.7%, and soybean meal concentration of 1%, resulting in a 8.12-fold increase in enzyme activity compared to the initial conditions. For Lactobacillus acidophilus, the optimal conditions were pH 6.74, temperature of 28.93°C, wheat bran concentration of 8% (w/v) , and soybean meal concentration of % (w/v) , leading to a 2.67-fold increase in enzyme activity compared to the baseline. Finally, the impact of various factors, such as pre-inoculation treatments (e.g., boiling or soaking the culture medium) and additives (including surfactants, oils, salts, and other compounds), was assessed for their potential to enhance enzyme production in both bacterial strains. The results showed that for Bacillus subtilis, the additives soybean meal, ammonium nitrate, ammonium chloride, zinc sulfate, corn oil, as well as heating the culture medium for 30 minutes and 2 hours, respectively increased phytase enzyme production by 41.65%, 12.75%, 10.91%, 22.57%, 20.44%, 24.96%, and 40.93% compared to the control medium.For Lactobacillus acidophilus, the additives soybean meal, Tween 80, Triton 100x, ammonium sulfate, zinc sulfate, corn oil, and pre-inoculation conditions such as soaking the culture medium for 48 hours and heating it for 30 minutes and 2 hours, respectively, improved enzyme production by 14.46%, 6.44%, 70%, 11.08%, 18%, 18.69%, 18%, 11%, and 67.23% compared to the basal medium.The parameters Tween 20, whey, yogurt powder, urea, and olive oil had a negative effect on enzyme production for both bacterial strains compared to the control, while soaking the culture medium for 24 hours and adding sesame oil had a neutral effect on both bacteria
  9. Keywords:
  10. Bacillus Subtilis ; Lactobacillus Acidophilus Bacteria ; Animal Feed ; Central Composite Design ; Response Surface Methodology ; Industrial Culture Medium ; Animal And Poultry Feed ; Anzyme Production

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