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

Authors

  • Xiang Zou,

    1. College of Pharmaceutical Sciences, Southwest University, Chongqing, P.R. China
    2. William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Ave., Columbus, Ohio 43210; telephone: 1-614-292-6611; fax: 614-293-3769
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  • Yipin Zhou,

    1. William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Ave., Columbus, Ohio 43210; telephone: 1-614-292-6611; fax: 614-293-3769
    2. Boprocessing Innovative Company, 4734 Bridle Path Ct., Dublin, Ohio
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  • Shang-Tian Yang

    Corresponding author
    1. William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Ave., Columbus, Ohio 43210; telephone: 1-614-292-6611; fax: 614-293-3769
    • William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Ave., Columbus, Ohio 43210; telephone: 1-614-292-6611; fax: 614-293-3769
    Search for more papers by this author

Abstract

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end-product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA-producing Aureobasidium pullulans strain ZX-10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high-titer equivalent to 87.6 g/L of malic acid and high-productivity of 0.61 g/L h in free-cell fermentation in a stirred-tank bioreactor. Fed-batch fermentations with cells immobilized in a fibrous-bed bioreactor (FBB) achieved the highest product titer of 144.2 g/L and productivity of 0.74 g/L h. The fermentation produced PMA was purified by adsorption with IRA-900 anion-exchange resins, achieving a ∼100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2 M sulfuric acid at 85°C, which followed the first-order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. Biotechnol. Bioeng. 2013; 110: 2105–2113. © 2013 Wiley Periodicals, Inc.

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