Isolation of Penicillium expansum WH-3 for the production of L(+)-tartaric acid

Abstract

The L(+)-form of tartaric acid (L(+)-TA) exists extensively in nature, and is widely used in the food, chemical, textile, building, and pharmaceutical industries (Su et al., 2001). The main method for L(+)-TA production is microbial transformation by cis-epoxysuccinate hydrolase (CESH), which can catalyze the asymmetric hydrolysis of cis-epoxysuccinic acid or its salts to TA or tartrate (Bao et al., 2019). Seventeen species containing CESH have been isolated so far. However, most species for L(+)-TA production have been reported from bacteria (Xuan and Feng, 2019). The only fungus isolated from soil by our lab recently, that could be used as catalyst for the process under acidic condition, is Aspergillus niger WH-2 (Bao et al., 2020). In order to find strains with new characteristics, this study attempted to isolate a new CESH source from fungi and investigate its application value.

Keywords: L(+)-Tartaric acid; cis-Epoxysuccinate hydrolase; Penicillium expansum; Isolation.

Fig. 1

Phylogenetic tree for strain WH-3 and related strains based on the internal transcribed spacer (ITS) sequence with sequence accession numbers

Fig. 2

Optimization of fermentation conditions for activity of mycelial pellet (U/g) and fermentation supernatant (U/L), including different inducers (a), carbon sources (b), inorganic nitrogen sources (c), organic nitrogen sources (d), temperatures (e), initial pH values (f), and fermentation time (g) A potato dextrose broth (PDB) medium fermented at 25 °C, pH 5.0 for 3 d was used as control for (a) and (b). A PDB medium with 10 g/L of glucose was used as control for (c). A PDB medium with 10 g/L of glucose and 1.4 g/L of NH₄NO₃ was used as control for (d). TA: tartaric acid. Data were expressed as mean±standard deviation (n=3)

Fig. 3

Fermentation curves for pH, biomass, activity of fermentation supernatant and mycelial pellet of Penicillium expansum WH-3 in a 5-L fermenter Data were expressed as mean±standard deviation (n=3)

Fig. 4

Characterization and biotransformation of CESH from mycelial pellet of Penicillium expansum WH-3 (a) Biotransformation curves of fermentation broth, mycelial pellet, and fermentation supernatant; (b) Effects of temperature on enzyme activity and stability; (c) Effects of pH on enzyme activity and stability; (d) Enantioselectivity analysis by high-performance liquid chromatography (HPLC); (e) Biotransformation curves of mycelial pellet at pH 4.5; (f) Conversion rate and enantiomeric excess (EE) value for repeated batch conversion by mycelial pellet at pH 4.5. CESH: cis-epoxysuccinate hydrolase. TA: tartaric acid. Data were expressed as mean±standard deviation (n=3)