Microbial export of lactic and 3-hydroxypropanoic acid: implications for industrial fermentation processes

Area of Science:

• Biotechnology
• Metabolic Engineering
• Biochemical Engineering

Background:

• Lactic acid and 3-hydroxypropanoic acid are key microbial products with significant industrial applications.
• Efficient microbial production is crucial for economic viability.
• Understanding product export is vital for optimizing fermentation processes.

Purpose of the Study:

• To review current knowledge on the export of lactic acid and 3-hydroxypropanoic acid from microbial cells.
• To analyze the bioenergetics of various export mechanisms.
• To identify export as a potential bottleneck in industrial bioproduction.

Main Methods:

• Literature review of microbial export mechanisms.
• Theoretical analysis of the bioenergetics of product export.
• Examination of energy requirements versus energy yield under different conditions.

Main Results:

• Product export can be a major constraint in industrial production.
• High product concentrations and low extracellular pH increase the energy demand for export.
• Export energy requirements can equal or exceed the energy yield from product formation at optimal recovery conditions.

Conclusions:

• Export energetics significantly impact microbial production efficiency.
• Sustaining production at high concentrations and low pH requires alternative ATP-yielding pathways, reducing substrate yield.
• Research into export mechanisms and energetics is essential for developing robust microbial production processes for weak acids.