A media design program for lactic acid production coupled with extraction by electrodialysis

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Nitrogen sources are a significant cost factor in industrial lactic acid fermentation.
• Developing cost-effective and sustainable alternatives is crucial for economic viability.
• Corn steep liquor (CSL) and spent brewery yeast are potential low-cost nitrogen sources.

Purpose of the Study:

• To investigate the efficacy of industrial media, specifically corn steep liquor (CSL) and spent brewery yeast, as nitrogen sources for lactic acid fermentation.
• To reduce the overall cost of nitrogen sources in lactic acid production.
• To evaluate the potential for reusing fermentation broth to minimize waste and raw material costs.

Main Methods:

• Batch fermentation experiments were conducted using varying concentrations of CSL and yeast extract (YE).
• Spent brewery yeast was tested as a sole nitrogen source.
• Lactic acid was recovered using electrodialysis.
• Fermentation broth reuse was assessed in subsequent batch cultures.

Main Results:

• 5% (v/v) CSL significantly improved lactic acid productivity by approximately 20% and resulted in a clearer fermentation broth.
• A combination of 3.1 g L(-1) YE and 5% CSL effectively substituted 15 g L(-1) YE.
• Spent brewery yeast at a concentration equivalent to 5% CSL served as a viable sole nitrogen source.
• Depleted broth supplemented with 5 g L(-1) YE showed reasonable performance in reuse experiments.

Conclusions:

• CSL and spent brewery yeast are effective and economical nitrogen sources for lactic acid fermentation.
• Optimized media formulations and broth reuse strategies can significantly reduce production costs and environmental impact.
• This study presents a sustainable approach to lactic acid production through cost-effective media optimization and waste minimization.