Sugar substrates for L-lysine fermentation by Ustilago maydis

Area of Science:

• Biotechnology
• Microbial Fermentation
• Amino Acid Production

Background:

• Ustilago maydis is a fungus capable of producing valuable biomolecules.
• L-lysine is an essential amino acid crucial for animal nutrition and human health.
• Investigating microbial production of l-lysine offers a sustainable alternative to chemical synthesis.

Purpose of the Study:

• To optimize extracellular l-lysine production by a Ustilago maydis mutant.
• To evaluate different sugar sources, including cane sugar, molasses, and clarified sugarcane juice.
• To determine the feasibility of using the fermentation concentrate as a feed supplement.

Main Methods:

• Cultivation of a Ustilago maydis mutant in various media.
• Optimization of fermentation parameters: inoculum size, pH, temperature, oxygen transfer rate (KLa), and fermentation time.
• Analysis of l-lysine concentration in the fermentation broth.
• Characterization of the fermentation broth concentrate.

Main Results:

• Enzymatically treated clarified sugarcane juice (medium J-3) yielded the highest l-lysine concentration of 2.9 g/L.
• Optimal conditions included 5% inoculum, pH 5.8, 30°C, KLa of 0.41 mmol O2/L/min, and 72-hour fermentation.
• The fermentation broth concentrate exhibited significant amino acid and vitamin content.

Conclusions:

• Ustilago maydis is a viable microorganism for the extracellular production of l-lysine.
• Clarified sugarcane juice is a suitable substrate for l-lysine fermentation.
• The resulting concentrate holds potential as a cost-effective feed supplement due to its nutritional value.