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Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis

Xiang Zou1, Yipin Zhou, Shang-Tian Yang

  • 1College of Pharmaceutical Sciences, Southwest University, Chongqing, P.R. China.

Biotechnology and Bioengineering
|February 26, 2013
PubMed

Insights

This study presents a new method for producing malic acid via polymalic acid (PMA) fermentation and hydrolysis. This efficient process overcomes limitations of direct malic acid fermentation, offering a promising route for industrial applications.

Area of Science:

  • Biotechnology
  • Biochemical Engineering
  • Industrial Microbiology

Background:

  • Malic acid is a valuable dicarboxylic acid and platform chemical derived from biomass.
  • Direct microbial production of malic acid faces challenges like low yield and end-product inhibition.

Purpose of the Study:

  • To develop a novel, efficient process for malic acid production.
  • To overcome limitations associated with direct malic acid fermentation.

Main Methods:

  • Screening and isolation of a polymalic acid (PMA)-producing Aureobasidium pullulans strain ZX-10.
  • Optimization of PMA fermentation using free-cell and immobilized-cell (fibrous-bed bioreactor) strategies.
  • Purification of PMA using anion-exchange resins.
  • Acid hydrolysis of purified PMA to yield malic acid.

Main Results:

  • Aureobasidium pullulans strain ZX-10 achieved high PMA titers (up to 144.2 g/L) and productivity (0.74 g/L/h) in fed-batch fermentation with immobilized cells.
  • PMA purification yielded ~100% purity with an 84% recovery rate.
  • Hydrolysis of PMA with sulfuric acid efficiently produced pure malic acid.

Conclusions:

  • The developed two-step process (PMA fermentation followed by hydrolysis) is an efficient and economical alternative for malic acid production.
  • This method effectively circumvents the end-product inhibition issues seen in direct malic acid fermentation.
  • The process shows significant potential for industrial-scale malic acid manufacturing.

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