Biotransformation of patulin to hydroascladiol by Lactobacillus plantarum

- Lactobacillus plantarum is an effective inhibitor of Penicillium expansum spore germination and mycelial growth.
- 80100% of the mycotoxin patulin was biotransformed by 1010L. plantarum/ml or cell free supernatant over 4 h.
- Patulin was biotransformed to ascladiol and then the novel metabolite hydroascladiol.
- L. plantarum growth temporaily restricted by 100 μg ml−1 patulin until biotransformation occurs.

Growth of Penicillium expansum, an ubiquitous mould found in stored fruit globallyt, was significantly restricted by exposure to 48 h cell-free supernatant of two strains of Lactobacillus plantarum (p < 0.001). In addition, the biotransformation of patulin, a toxic secondary metabolite formed by P. expansum, on exposure to L. plantarum cells and cell-free supernatant highlights the potential of this GRAS microbe as a biocontrol agent. Up to 80% of patulin was biotransformed following a 4 h incubation with 1010 cells ml−1 (37 °C) forming E- and Z-ascladiol. The formation of these products was more pronounced at elevated pH and cell density. Exposure to cell free supernatant or sonicated cells resulted in complete patulin biotransformation with heat treatment inhibiting this effect. The ascladiol isomers were then further transformed over a 4-week cell-free incubation (4 °C) into the novel metabolite hydroascladiol (5-(2-hydroxyethyl)-4-(hydroxymethyl) furan-2(5H)-one) which produced a 2 amu difference across the main tandem mass fragments (113.1, 129.0, 139.0), compared to ascladiol (111.1, 127.0, 137.0). This suggests hydroascladiol could be a better biomarker of initial patulin levels in some food commodities. The in vitro biotransformation data and resistance of L. plantarum to highly elevated concentrations of patulin (≥100 μg ml−1) suggest L. plantarum is a potential candidate for food preservation or remediation strategies and future work with fruit products is proposed.