Mechanism of patulin biodegradation by a reductase from Saccharomyces cerevisiae and its potential application to apple juice

Abstract

Bioenzymatic degradation exhibits great potential for mycotoxins removal. So far, little is known about patulin (PAT) degrading enzymes from Saccharomyces cerevisiae. Here, the degradation mechanism of PAT by a free methionine-R-sulfoxide reductase (FRMSR) from S. cerevisiae was investigated. The results showed that purified FRMSR had high degradability without cofactor and displayed strong substrate specificity. The optimal degradation conditions in aqueous solution were 37 °C and pH 7.0. Isothermal titration calorimetry and molecular docking suggested that the PAT degradation by FRMSR was related to the hydrogen bonds formed between amino acids with PAT. Site-specific mutagenesis indicated that the mutation of Asp151 had the most significant effect on the degradation rate. Furthermore, the addition of FRMSR successfully degraded 88.16 % of PAT in apple juice without affecting its soluble solids content, pH value, titrable acidity and total phenols. These findings could provide valuable insights into the development of PAT-degrading enzymes in apple products and their industrial applications.