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Efficient Production of Polymalic Acid by a Novel Isolated Aureobasidium pullulans Using Metabolic Intermediates and

Wei Zeng1,2, Bin Zhang1,2, Guiguang Chen1,2

  • 1State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, 530004, Guangxi, China.

Applied Biochemistry and Biotechnology
|July 18, 2018
PubMed

Insights

Researchers isolated a novel Aureobasidium pullulans strain for high-titer polymalic acid (PMA) production. Metabolic control strategies were developed, revealing insights into PMA biosynthesis pathways.

Area of Science:

  • Biotechnology and Industrial Microbiology
  • Polymer Science
  • Metabolic Engineering

Background:

  • Polymalic acid (PMA), a linear anionic polyester of L-malic acid, shows promise in biomedical and material applications.
  • Efficient and high-titer production of PMA is crucial for its commercial viability.
  • Understanding the biosynthesis pathway of PMA in microbial systems is essential for strain and process optimization.

Purpose of the Study:

  • To isolate and identify a novel microbial strain capable of high-yield polymalic acid (PMA) production.
  • To characterize the produced PMA using spectroscopic methods.
  • To investigate metabolic control strategies for enhancing PMA production and elucidate its biosynthesis pathway.

Main Methods:

  • Isolation and identification of Aureobasidium pullulans var. melanogenum GXZ-6 using morphological and DNA sequencing techniques.
  • Characterization of polymalic acid (PMA) by Fourier-transform infrared spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR) (13C-NMR, 1H-NMR).
  • Optimization of fermentation medium and conditions, including the addition of metabolic intermediates and inhibitors, in a 10-L fermentor.

Main Results:

  • A novel strain, Aureobasidium pullulans var. melanogenum GXZ-6, was successfully isolated and identified.
  • The optimized fermentation process achieved a high PMA titer of 62.56 ± 1.18 g L-1 with a productivity of 0.35 g L-1 h-1.
  • Metabolic analysis indicated that citrate, malate, malonate, and maleate enhanced PMA production, while succinate and fumarate inhibited it, suggesting a unique biosynthesis pathway possibly involving the glyoxylate cycle.

Conclusions:

  • Aureobasidium pullulans var. melanogenum GXZ-6 is a promising strain for high-titer polymalic acid (PMA) production.
  • A simple metabolic control strategy using specific intermediates and inhibitors can significantly boost PMA yield.
  • This study provides novel insights into the biosynthesis pathway of PMA in A. pullulans, differing from previously studied strains.
Keywords:
Aureobasidium pullulans var. melanogenumBiosynthesis pathwayHigh-titerMetabolic controlPolymalic acid

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