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Increasing patulin contamination in fruits and fruit-derived products has become a major challenge for the food industry. Biological methods of patulin control have an important role to play owing to their safety and efficiency. In this study, we used the yeast Pichia caribbica to degrade patulin effectively. The intermediate degradation products of patulin by P. caribbica were identified as (E)- and (Z)-ascladiol using high performance liquid chromatography and liquid chromatography-tandem mass spectroscopy. Only (E)-ascladiol was detected in the products of patulin degradation by intracellular enzymes. Toxic analyses on Escherichia coli Top10 cells, Arabidopsis thaliana, and human esophageal epithelial cells (Het-1a) showed that the intermediate degradation product ascladiol and the final degradation products were significantly less toxic and almost non-toxic compared to patulin (p 0.05) compared to patulin. Analysis of the characteristics and toxicity of the degradation products of patulin by P. caribbica demonstrate that ascladiol is less toxic and the final degradation products are not poisonous, therefore patulin detoxification strategies using P. caribbica are good approaches to limit the patulin risks.

Fruits are vulnerable to pathogen infection caused by decay during growth and storage, which causes huge economic losses. The aim of this study was to investigate the biocontrol efficacy of the antagonistic yeast Sporidiobolus pararoseus Y16 in the control of Aspergillus niger decay, and natural decay of table grapes and the possible mechanisms involved. The results showed that S. pararoseus Y16 at different concentrations significantly inhibited A. niger decay of table grapes compared with the control. Besides, the population dynamics results showed that S. pararoseus Y16 could rapidly survive and proliferate in grape wounds or on grape surfaces at 20 °C. Moreover, S. pararoseus Y16 treatment did not impair postharvest qualities of table grapes. Results also showed that treatment with S. pararoseus Y16 enhanced the enzyme activities of polyphenol oxidase (PPO), catalase (CAT), phenylalanine ammonia-lyase (PAL) and ascorbate peroxidase (APX) in table grapes. Furthermore, the gene expression levels of PPO, CAT, PAL and APX were increased by gene level verification. All these results indicated that S. pararoseus Y16 has great potential for development of commercial formulations to control postharvest pathogens on table grapes. These findings revealed that the enhanced gene expression and enzyme activities are the mechanisms involved in the biocontrol, while the yeast outcompeted the fungus for space and nutrients.