Optimization of erythritol production through fermentation using molasses as carbon source

Area of Science:

• Biotechnology and Fermentation Science
• Food Science and Technology
• Metabolic Engineering

Background:

• Erythritol, a sugar alcohol, is a valuable sugar substitute for diabetic patients.
• Microbial production of erythritol is influenced by osmotic pressure, stress, and nutrient availability.
• Optimizing carbon source, nitrogen source, and their ratio is crucial for efficient erythritol biosynthesis.

Purpose of the Study:

• To determine optimal concentrations of molasses (carbon source) and yeast extract (nitrogen source) for erythritol production.
• To investigate the impact of carbon-to-nitrogen (C/N) ratio, NaCl concentration, and pH on erythritol yield.
• To compare the efficacy of batch and fed-batch fermentation systems for maximizing erythritol productivity.

Main Methods:

• The One-Factor-at-A-Time (OFAT) method was employed to systematically optimize production parameters.
• Varied concentrations of molasses, yeast extract, NaCl, and pH levels were tested.
• Batch and fed-batch fermentation strategies were compared for erythritol yield and productivity.

Main Results:

• Optimal conditions in batch fermentation included 200 g/L molasses, 7 g/L yeast extract (C/N ratio of 200/7), and 25 g/L NaCl, yielding 17.48 g/L erythritol.
• The optimal pH for erythritol production was determined to be 5.
• Fed-batch fermentation significantly enhanced erythritol concentration to 26.52 g/L, with improved yield (0.501 g/g) and productivity (0.158 g/Lh).

Conclusions:

• Optimizing carbon and nitrogen sources, NaCl concentration, and pH are critical for maximizing erythritol production.
• Fed-batch fermentation is a superior system for achieving higher erythritol yields and productivity compared to batch.
• These findings provide a foundation for scalable industrial production of erythritol.