A novel enzyme from Rhodotorula mucilaginosa Aldolase: Isolation, identification and degradation for patulin in apple juice

Patulin is a mycotoxin produced by Penicillium species that can cause severe food safety concerns. Biological enzymes are considered one of the promising methods for degrading patulin. The purpose of this study was focused on isolating and purifying Aldolase from Rhodotorula mucilaginosa. The results showed that the molecular weight of purified Aldolase was 36 kDa. The Aldolase had an optimal pH 7.0 and was stable at a pH range of 5.5–7.0. The optimum temperature for Aldolase was 25 °C and exhibited thermostability in the range of 4–25 °C. The Aldolase activity was induced moderately by Ca2+, Cu2+, PMSF and SDS, while Fe3+ and EDTA significantly inhibited the activity. The kinetic parameters (Km and Vmax) for Aldolase were 109.46 mM and 4.34 mM/h, respectively. When 0.7 mg/mL of Aldolase was added, 2 mg/L of patulin in apple juice can be degraded. Moreover, there is no significant difference in the quality parameters and volatile compounds before and after degradation in apple juice. Finally, the Aldolase gene was successfully cloned and expressed in E. coli. Meanwhile, the purified cloned Aldolase has an excellent patulin degradation ratio of more than 99% (15 mg/L). These findings suggested that Aldolase was a promising material for patulin degradation.