This study optimized enniatin production by Fusarium sambucinum grown in surface culture on liquid media. Enniatins are cyclodepsipeptides with antimicrobial properties that act on biological membranes. The researchers systematically investigated physical and nutritional conditions affecting yield. They found that light was essential for significant enniatin accumulation, and moderate temperature (20°C) favored production over higher temperatures (25-30°C). On semidefined medium containing 5% lactose and 0.8% tryptone at 20°C with daily 12-hour photoperiods, they achieved yields of 1.7 g enniatins per liter (10% of mycelial dry weight). Enniatins accumulated in mycelium only after growth nearly ceased and nitrogen became limiting. Glucose inhibited sporulation, while organic acids like sodium acetate and citrate supported it. The optimal carbon-to-nitrogen ratio was approximately 14-25 depending on nutrient source. This fermentation-based approach provided an economical alternative to chemical synthesis for producing these bioactive compounds in quantity.

Key findings

• Light was required for significant enniatin production; cultures in darkness yielded much lower amounts
• Optimal temperature was 20°C; yields decreased substantially at 25°C and 30°C
• Lactose was the superior carbon source, yielding more than twice the enniatin of glucose or other common sugars tested
• Best nitrogen source was tryptone; media with ammonium nitrate became too acidic with minimal enniatin production
• Optimal conditions (5% lactose, 0.8% tryptone, 20°C, 12-hour daily light) yielded 1.7 g enniatins/liter or 10% of mycelial dry weight