title: Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis.
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.
authors: College of Pharmaceutical Sciences, Southwest University, Chongqing, P.R. China.
authors: Xiang
authors: X
authors: Zou
authors: Yipin
authors: Y
authors: Zhou
authors: Shang-Tian
authors: ST
authors: Yang
mesh_terms: D001203:Ascomycota / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods; D018914:Cells, Immobilized / Q000378:metabolism; D005285:Fermentation; D006868:Hydrolysis; D008293:Malates / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism*
chemical_list: D008293:Malates; D011108:Polymers; C121060:poly(malic acid); C030298:malic acid