L-malic acid, a four-carbon dicarboxylic acid (figure 1), was first isolated from unripe apples in 1785. It has been widely used in the beverage and food industry as an acidulant and flavor enhancer, and in metal cleaning, textile finishing, pharmaceuticals and agriculture. As an intermediate of the tricarboxylic acid (TCA) cycle, L-malic acid is one of the most promising building block chemicals that can be produced from renewable sources.
Fig. 1 Chemical structure of L-malic acid
Biosynthesis of L-Malic Acid
With increasing environmental concerns, there are growing interests in developing technologies that utilize renewable sources for the production of fuels and chemicals. Although malate and calcium malate can be extracted from fruit and eggshells, these processes are not economical. In fact, L-malic acid can be produced i) from pyruvic acid via oxaloacetic acid by a one-step fermentation, or ii) via the conversion of fumaric acid under catalysis of fumarase, or iii) through acid hydrolysis of polymalic acid (PMA)[1].
- L-malic acid production by one-step fermentation
Several native strains and metabolically engineered strains were found to be able to produce L-malic acid. For example:
i) L-malic acid can be accumulated and excreted by Aspergillus flavus under aerobic conditions in a medium containing a high glucose concentration.
ii) It has been found that a glucose concentration of 30%, initial pH 5.0 and 25 ℃ incubation temperature are the optimum conditions for Zygosaccharomyces rouxii V19 to ferment glucose to produce L-malic acid.
iii) Genetic modification of Saccharomyces cerevisiae can be used to achieve efficient L-malic production.
iv) Other strains can produce L-malic acid include genetically modified Torulopsis glabrata, Schizophylium commune, Bacillus subtilis, Escherichia coli, and so on.
- Biotransformation using fumarase
Fumarase can be used for the conversion of fumaric acid to malic acid. The bioconversion of fumaric acid to L-malic acid can also be performed by various species of yeasts such as Saccharomyces, Schizosaccharomyces Candida, Pichia and Dipodascus.
L-malic acid can be produced from polymalic acid (PMA) through acid hydrolysis, in which PMA comes from glucose and other glucose containing materials through fungal fermentation.
Our Biosynthetic L-Malic Acid
L-malic acid can be synthesized by chemical means or by biosynthesis ways. Our L-malic acid is obtained by fermentation. Basic properties are listed in the following table:
| Product Name | Biosynthetic L-Malic Acid |
| Catalog | BIOS291519 |
| Appearance | White crystal or crystalline powder |
| L-malic acid assay | ≥ 99.0% |
| Specific rotation [a]20D | -1.6°~-2.6° |
| Burning residue | ≤ 0.10% |
| Sulfate (in SO4) | ≤ 0.02% |
| Chloride (in Cl) | ≤ 0.004% |
| Fumaric acid | ≤ 0.5% |
| Maleic acid | ≤ 0.05% |
| Heavy metal (in Pb) | ≤ 10.0 mg/kg |
| Arsenic (As) | ≤ 2.0 mg/kg |
| Lead (Pb) | ≤ 2.0 mg/kg |
Alfa Chemistry is a professional supplier of biosynthetic L-malic acid. For high quality products, professional technical service, use suggestion and latest industry news, please feel free to contact us.
Reference
- Chi, Z., Wang, Z.-P., Wang, G.-Y., Khan, I., & Chi, Z.-M. Microbial biosynthesis and secretion of L-malic acid and its applications. Critical Reviews in Biotechnology, 2014, 36(1), 99–107.
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