Antimycin A fermentation. II. Fermentation in aerated-agitated fermenters

Area of Science:

• Microbiology
• Biotechnology
• Fermentation Science

Background:

• Antimycin A is a valuable secondary metabolite with significant biological activity.
• Previous studies on Streptomyces sp. antimycin A production were limited to shake flask cultures.
• Scaling up fermentation processes presents challenges in optimizing microbial growth and product yield.

Purpose of the Study:

• To reproduce and optimize Streptomyces sp. fermentation characteristics in aerated-agitated fermenters.
• To enhance the yield and production rate of antimycin A.
• To identify critical parameters for large-scale antimycin A biosynthesis.

Main Methods:

• Utilized three high-antimycin A-producing Streptomyces sp. strains.
• Employed a three-stage fermentation process in aerated-agitated fermenters.
• Optimized medium composition (soy flour, glucose, ammonium sulfate, calcium carbonate) and controlled pH (6) and temperature (25°C).
• Implemented continuous soybean oil addition (1.25%/day) and ammonium hydroxide for pH control and nitrogen supplementation.

Main Results:

• Successfully reproduced shake flask fermentation characteristics in fermenters.
• Eliminated the intermediate lag period observed in shake flasks by modifying fermentation course.
• Achieved maximal antimycin A yields exceeding 9 g/liter.
• Demonstrated that ammonium hydroxide addition was crucial and could not be replaced by NaOH or KOH.
• Observed a constant production rate of antimycin A from day 2 to day 6.

Conclusions:

• Fermentation in aerated-agitated fermenters is a viable method for high-yield antimycin A production.
• Continuous soybean oil addition and precise pH control are key factors for optimizing Streptomyces sp. fermentation.
• The study provides a foundation for industrial-scale production of antimycin A.