Patulin biodegradation using Pichia ohmeri and Saccharomyces cerevisiae

Abstract

The effectiveness of Pichia ohmeri and Saccharomyces cerevisiae in the biodegradation of patulin was evaluated in vitro. Patulin is a toxin produced by Penicillium expansum, the predominant fungal contaminant in post-harvest apple. The biodegradation experiment was carried out in culture medium (Yeast Medium broth, YM) and commercial apple juice. These substrates were artificially contaminated with patulin previously produced by P. expansum strain 2 in malt extract broth and purified over a silica gel column. The YM broth was inoculated with P. ohmeri 158 with proved anti-P. expansum activity, whereas the apple juice was inoculated with dried Saccharomyces cerevisiae cells. The residual patulin in contaminated substrates was determined by reversed-phase HPLC. P. ohmeri 158 in YM broth degraded over 83% of the initial 223 µg (8.92 µg/ml) of patulin after incubation at 25 °C for two days under static conditions; after five days of incubation, this percentage was greater than 99%, and patulin levels fell below the limit of detection after 15 days. In the apple juices inoculated with 0.25 g/l of commercial dried S. cerevisiae cells (corresponding 1.8 x 107 cells/ml), 96% of patulin was degraded (initial contamination of 4.5 µg/ml of patulin) after 143 hours of incubation at 25 °C under static conditions. However, 90% degradation occurred when the juice was contaminated with 7.0 µg/ml under the same conditions, indicating that the biodegradation rate is concentrationdependent. The effective biodegradation of patulin using P. ohmeri 158 and S. cerevisiae demonstrates a promising application for innocuous yeast isolated from natural microbiota in the biological control, which can prevent both fruit spoilage and P. expansum mycotoxin contamination.

Mycotoxins – prevention and decontamination by yeasts

“…In vitro tests indicated that P. caribbica degraded the mycotoxin directly . Several other yeast species including M. pulcherrima , P. ohmeri , R. kratochvilovae , S. cerevisiae , and Sporobolomyces roseus have also been investigated for their patulin‐degrading capabilities . A R. kratochvilovae (a basidiomycote yeast) strain was able to convert patulin to less toxic desoxypatulinic acid (DPA), representing a novel biodegradation pathway and detoxification process .…”

The Possible Mechanisms Involved in Degradation of Patulin by Pichia caribbica

“…In view of this, many researches have shown that some antagonist yeasts could directly inhibit the production of patulin. Through almost 30 years of research, dozens of yeasts, including Pichia caribbica [21], Rhodotorula glutinis [22], Pichia ohmeri [23], Rhodosporidium kratochvilovae [24], Gluconobacter oxydans [25], and several others have been shown to degrade patulin, and inhibited the growth of P. expansum . Coelho et al [26] reported that patulin concentration of 223 µg was decreased over 83% by P. ohmeri 158 cells when incubated at 25 °C for two days at a humidity >99.…”

Mycotoxin Contamination of Beverages: Occurrence of Patulin in Apple Juice and Ochratoxin A in Coffee, Beer and Wine and Their Control Methods

“…Besides being successful, this method is much better understood compared with other decontamination methods. Approximately 96% of patulin can be removed during yeast fermentation [242]. Stinson et al [243] examined and found that out of eight yeast strains tested six reduced patulin levels to below detectable levels, while all eight strains resulted in a 99% or better decrease in total patulin content.…”