Fungus could lead to improved safety of apple and other fruit products

‘To our knowledge, TUS-MM1 is the first filamentous fungus shown to be capable of degrading patulin into desoxypatulinic acid.’

Researchers from Tokyo University of Science, Japan, have identified a filamentous fungal mould strain, Acremonium sp (TUS-MM1), which is effective in degrading the mycotoxin patulin. This mycotoxin is produced by several types of fungi and is toxic to humans, mammals, plants and microorganisms.

The fungi species that produce patulin are often present on damaged or decaying fruit, specifically apples and contaminated apple products such as sauce, juice and cider. In environments lacking good hygiene, the mycotoxin can lead to a number of negative health impacts including nausea, ulcers, intestinal haemorrhage, DNA damage and increased cancer risk. This has led to many countries imposing restrictions on the permitted levels of patulin in food products, specifically baby foods, as infants are more vulnerable to its effects.

Publishing their work in the journal MicrobiologyOpen, the researchers isolated the mould strain, TUS-MM1, through cultured microorganisms from 510 soil samples in a patulin-rich environment, looking for those that would thrive in the presence of the mycotoxin.

The researchers then used high-performance liquid chromatography (HPLC) to determine which of the most promising microorganisms were best at degrading patulin into less harmful chemical substances. Once TUS-MM1 was isolated, the researchers investigated how the microorganism was able to degrade the patulin.

They found that when TUS-MM1 absorbs patulin, it is able to add hydrogen atoms, degrading the toxin to desoxypatulinic acid, which is less harmful. Further analysis revealed that the agent responsible for transformation of patulin outside the cells was a thermally stable, but highly reactive compound with a low molecular weight.

Dr Toshiki Furuya, Associate Professor at the Faculty of Science and Technology of the Department of Applied Biological Science at TUS said: ‘When we started this research, only one other filamentous fungal strain had been reported to degrade patulin. However, prior to the present study, no degradation products had ever been identified. In this regard, to our knowledge, TUS-MM1 is the first filamentous fungus shown to be capable of degrading patulin into desoxypatulinic acid.’