L-Lactic acid fermentation by Enterococcus faecium: a new isolate from bovine rumen.

Area of Science:

• Biotechnology
• Microbial Fermentation

Background:

• L-lactic acid is a valuable chemical with diverse industrial applications.
• Efficient and cost-effective production methods are crucial for meeting market demand.

Purpose of the Study:

• To develop a novel, adaptable microbial strain for efficient enantioselective L-lactic acid production.
• To reduce operational costs and ensure suitability for large-scale fermentation.

Main Methods:

• Screening and characterization of Enterococcus faecium S.156 for L-lactic acid production.
• Optimization of fermentation conditions including temperature, pH, and oxygen levels.
• Evaluation of cost-saving nutrient substitutions.

Main Results:

• Enterococcus faecium S.156 achieved high L-lactic acid yield (126 g/l) with excellent optical purity (99.7%) and productivity (5.25 g/l.h).
• Optimal production occurred between 32-40 °C and pH 5.5-6.5; oxygen had no significant impact.
• Folic acid and Fe(2+) substitution for yeast extract significantly reduced costs.

Conclusions:

• Enterococcus faecium S.156 exhibits unique characteristics and economic advantages for industrial L-lactic acid production.
• The strain's adaptability and efficient fermentation profile make it a promising candidate for scale-up.