Researchers from Tokyo University of Science (TUS) have discovered a type of fungus that can change a harmful toxin called patulin, often found in damaged fruits, into less harmful forms.

Patulin is produced by certain fungi that grow on fruits like apples, pears, and grapes. The scientists in Japan found a new kind of fungus that can break down patulin and turn it into substances that are not as harmful.

This discovery helps the world understand how patulin can be made less toxic naturally and could lead to better ways of preventing its harmful effects in food.

Patulin is a natural compound that can sometimes be found in certain fruits, especially those that are a bit old or damaged. It's produced by certain molds that might grow on these fruits.

While Patulin is not usually a big concern in small amounts, high levels of it might not be good for the health of humans, mammals, plants, and microorganisms. In places where proper hygiene is not maintained during food production, there's a higher risk of patulin contamination.

This is because many of the fungi that produce patulin thrive on fruits that are spoiled or decaying, especially apples. They can also affect apple-based products like applesauce, apple juice, jams, and ciders.

A team of researchers, led by Associate Professor Toshiki Furuya from Tokyo University of Science (TUS), has been actively investigating potential solutions to counter the harmful effects of patulin toxicity.

In their recent study published in MicrobiologyOpen (Volume 12, Issue 4, August 11, 2023), the researchers, including Ms. Megumi Mita, Ms. Rina Sato, and Ms. Miho Kakinuma, sought to identify soil microorganisms capable of mitigating patulin's harmful impact.

The researchers conducted their study in two main phases. Firstly, they cultivated microorganisms from 510 soil samples in an environment with high levels of patulin. They were specifically searching for microorganisms that could thrive even in the presence of this toxin.

In the subsequent phase, they performed a second screening using an advanced technology called high-performance liquid chromatography (HPLC) to identify the microorganisms that were most effective at breaking down patulin into safer chemical forms.

Ultimately, they pinpointed a type of filamentous fungus, known as Acremonium sp. or "TUS-MM1," belonging to the Acremonium genus, that exhibited the desired characteristics.

The research team then conducted a series of experiments aimed at uncovering the mechanisms employed by TUS-MM1 to break down patulin. They achieved this by cultivating the mold strain in a solution abundant with patulin, and closely examining the substances that emerged within and outside the cells as a response to patulin exposure over a period of time.

A notable discovery emerged from these experiments. The cells of TUS-MM1 were observed to convert absorbed patulin into desoxypatulinic acid, a compound significantly less harmful than patulin itself. This transformation involved the addition of hydrogen atoms to the patulin molecule.

Dr. Furuya, reflecting on the research, noted that at the outset of their investigation, only a single filamentous fungal strain had been reported for its ability to break down patulin.

Importantly, no breakdown products had been identified until this study. Consequently, as far as their knowledge goes, TUS-MM1 represents the inaugural instance of a filamentous fungus demonstrated to effectively transform patulin into desoxypatulinic acid.

“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,” Dr Furuya said.

The research team discovered that specific substances released by the TUS-MM1 cells could also lead to the conversion of patulin into different molecules. By combining patulin with the external secretions produced by TUS-MM1 cells and utilizing HPLC, the researchers witnessed the formation of diverse degradation products stemming from patulin.

Encouragingly, tests conducted on E. coli bacterial cells demonstrated that these resultant products were considerably less harmful compared to patulin itself. A more detailed analysis of the chemical properties revealed that the key catalyst for patulin conversion outside the cells was a compound with a low molecular weight that remains stable at high temperatures but is very reactive.

The study's findings bring us closer to effective methods for managing patulin levels in food. Dr. Furuya said understanding how microorganisms can break down patulin pathways not only enhances our knowledge of natural processes but also opens the door to applying these organisms for biocontrol purposes.

“Elucidating the pathways via which microorganisms can degrade patulin would be helpful not only for increasing our understanding of the underlying mechanisms in nature but also for facilitating the application of these organisms in biocontrol efforts.”

Patulin is linked to various health risks like nausea, lung congestion, ulcers, and even more severe problems like DNA damage, weakened immune system, and higher chances of cancer. This makes patulin toxicity a significant global concern.

To address this, many countries have set limits on how much patulin can be in food, especially baby food, as babies are more sensitive to it.

Dealing with patulin poisoning involves treatments like oxygen therapy, immunotherapy, detoxification therapy, and nutrient therapy. However, since preventing a problem is usually better than treating it, researchers have been seeking effective methods to reduce patulin's harmful effects on food.