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Published on: June 13, 2019
A high molecular weight polymalate is synthesized by the whole genome duplicated strain Aureobasidium melanogenum OUC
Cong-Yan Qi1, Zhe Chi2, Guang-Lei Liu2
1College of Marine Life Sciences, Ocean University of China, Yushan Road, No. 5, Qingdao, China.
Abstract:
Polymalate (PMA) produced by the whole genome duplicated strain Aureobasidium melanogenum OUC had a high molecular weight (Mw) of 3.9 × 105 Da while the Mw of PMA produced by A. melanogenum ATCC62921 was 3.8 × 104 Da. Therefore, the purified PMA produced by A. melanogenum OUC could form hydrogel and film and the precipitated Ca2+-PMA looked like noodle whereas the purified PMA produced by A. melanogenum ATCC62921 could not form such a hydrogel and a film and the precipitated PMA was powder-like. The high Mw PMA biosynthesis in A. melanogenum OUC was also controlled by the PMA synthetase. However, it was still unclear why the PMA synthetase in A. melanogenum OUC could catalyze the high Mw PMA biosynthesis. Both removal of two copies of the PKS genes and overexpression of the PYC1 gene, the VGB gene and the CRZ2 gene rendered the new transformant Crz46 to produce 34.6 ± 0.3 g/L of extracellular Ca2+-PMA with Mw of 4.9 × 105 Da while its native A. melanogenum OUC only produced 17.2 ± 0.3 g/L of Ca2+-PMA. During the 10-Liter fermentation, 35.6 ± 1.2 g/L of Ca2+-PMA and 13.9 g/Lof cell mass were produced within 168 h, leading to the yield of 0.36 g/g of glucose and the productivity of 0.21 g/L/h. This was the first time to report that the whole genome duplicated strain A. melanogenum OUC and its engineered mutants could produce the high Mw PMA.
Insights
Aureobasidium melanogenum OUC produces high molecular weight polymalates (PMA) with unique hydrogel and film-forming properties. Genetic engineering enhanced PMA production in this yeast, achieving high yields and productivity.
Area of Science:
- Microbiology
- Biochemistry
- Biotechnology
Background:
- Aureobasidium melanogenum OUC, a whole genome duplicated strain, produces high molecular weight polymalate (PMA).
- The molecular weight (Mw) of PMA from A. melanogenum OUC (3.9 × 10⁵ Da) is significantly higher than that from A. melanogenum ATCC62921 (3.8 × 10⁴ Da).
- High Mw PMA exhibits distinct physical properties, forming hydrogels and films, unlike low Mw PMA.
Purpose of the Study:
- To investigate the biosynthesis of high molecular weight PMA in A. melanogenum OUC.
- To understand the role of PMA synthetase in high Mw PMA production.
- To enhance PMA production through genetic engineering of A. melanogenum OUC.
Main Methods:
- Comparative analysis of PMA produced by different strains of A. melanogenum.
- Genetic modification of A. melanogenum OUC, including gene deletion (PKS genes) and overexpression (PYC1, VGB, CRZ2 genes).
- Fermentation studies to determine PMA yield and productivity.
Main Results:
- Engineered strain Crz46 produced 34.6 ± 0.3 g/L of extracellular Ca²⁺-PMA with Mw of 4.9 × 10⁵ Da, nearly double the native strain's production (17.2 ± 0.3 g/L).
- Large-scale fermentation (10-Liter) yielded 35.6 ± 1.2 g/L of Ca²⁺-PMA within 168 hours.
- Achieved a glucose yield of 0.36 g/g and productivity of 0.21 g/L/h.
Conclusions:
- Whole genome duplicated A. melanogenum OUC and its engineered mutants are capable of producing high molecular weight PMA.
- Genetic engineering strategies can significantly enhance PMA yield and productivity.
- This study provides the first report on high Mw PMA production by A. melanogenum OUC and its engineered variants.
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