Wenna Bao1,2, Hongxiu Liao3,4, Yi Chen3,4, Qianqian Huang3,4, Wendi Huang3,4, Rui Fang3,4, Shiwang Liu3,4. 1. School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, 310023, China. wennabao@163.com. 2. Zhejiang Provincial Key Laboratory for Chemical and Biological Processing Technology of Farm Products, Hangzhou, 310023, China. wennabao@163.com. 3. School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, 310023, China. 4. Zhejiang Provincial Key Laboratory for Chemical and Biological Processing Technology of Farm Products, Hangzhou, 310023, China.
Abstract
OBJECTIVES: To isolate a novel cis-epoxysuccinate hydrolase (CESH)-producing fungus for production of L( +)-tartaric acid, before this, all strains were selected from bacteria. RESULTS: A CESH-producing fungus was first isolated from soil and identified as Aspergillus niger WH-2 based on its morphological properties and ITS sequence. The maximum activity of hyphaball and fermentation supernatants was 1278 ± 64 U/g and 5.6 ± 0.3 U/mL, respectively, in a 5 L fermenter based on the conditions optimized on the flask. Almost 70% of CESH was present in hyphaball, which maintained 40% residual activity at pH 4.0 and showed a good acid stability (pH 3.0-10.0), high conversion rate (> 98%), and enantioselectivity (EE > 99.6%). However, the reported CESHs from bacteria can't be catalyzed under acidic conditions. CONCLUSIONS: The Aspergillus niger WH-2 was the first reported CESH-producing fungus, which could biosynthesize L ( +)-tartaric acid under acidic conditions and provide an alternative catalyst and process.
OBJECTIVES: To isolate a novel cis-epoxysuccinate hydrolase (CESH)-producing fungus for production of L( +)-tartaric acid, before this, all strains were selected from bacteria. RESULTS: A CESH-producing fungus was first isolated from soil and identified as Aspergillus niger WH-2 based on its morphological properties and ITS sequence. The maximum activity of hyphaball and fermentation supernatants was 1278 ± 64 U/g and 5.6 ± 0.3 U/mL, respectively, in a 5 L fermenter based on the conditions optimized on the flask. Almost 70% of CESH was present in hyphaball, which maintained 40% residual activity at pH 4.0 and showed a good acid stability (pH 3.0-10.0), high conversion rate (> 98%), and enantioselectivity (EE > 99.6%). However, the reported CESHs from bacteria can't be catalyzed under acidic conditions. CONCLUSIONS: The Aspergillus niger WH-2 was the first reported CESH-producing fungus, which could biosynthesize L ( +)-tartaric acid under acidic conditions and provide an alternative catalyst and process.