Conversion of the Mycotoxin Patulin to the Less Toxic Desoxypatulinic Acid by the Biocontrol Yeast Rhodosporidium kratochvilovae Strain LS11

Abstract

ABSTRACT:The infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After R. kratochvilovae LS11 had been incubated in the presence of 13 C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process.

Two rapid assays for screening of patulin biodegradation

“…Thus, the observed decrease in patulin over the 3 days of incubation corresponded to the formation of DPA. Its identity was confirmed by comparing its retention time with the one of a desoxypatulinic acid standard, as described by Castoria et al (2011). The quantification of patulin and desoxypatulinic acid (Fig.…”

Searching for Genes Responsible for Patulin Degradation in a Biocontrol Yeast Provides Insight into the Basis for Resistance to This Mycotoxin

“…Patulin was produced by P. expansum strain 7015 and purified as described by Castoria et al (19) with slight modifications. Briefly, P. expansum was inoculated in potato dextrose broth (PDB) medium diluted with H 2 O to a final ratio of 1:10 and incubated at 24°C for 7 days on an orbital shaker.…”

“…IAM 13481 with patulin and analyses of mycotoxin fate. The analysis of patulin persistence in LiBa medium was performed as described by Castoria et al (14,19) with minor modifications. Sporobolomyces sp.…”

“…The major patulin degradation product formed in vitro by R. kratochvilovae LS11 was identified as desoxypatulinic acid (DPA), which was reported to be nontoxic to different microorganisms (17,18) and to cultured human lymphocytes (19). Additional mechanisms that result in breakdown of patulin exist but do not generate DPA, as has been reported for Saccharomyces cerevisiae during fermentation of apple juice (20) and for the bacterium Gluconobacter oxydans (21).…”

Possible Natural Toxins in Organic Livestock Farming

“…Many strategies to prevent mycotoxin contamination of food and animal feed have been developed. Various crop genotypes resistant to fungus infection [106][107][108] , pre-harvest control strategies [89,109] , field and harvest management as well as post-harvest applications including improving drying and storage conditions [110][111][112][113] , and the use of biological agents [114][115][116] have been shown important in the prevention of mycotoxigenic mould growth and mycotoxin formation. Preservation can be facilitated by low temperature storage, ensiling, dehydration or the addition of appropriate chemicals [54] .…”