Effects of Temperature, pH, and Relative Humidity on Growth of Penicillium crustosum OM1 Isolated from Pears and Its Penitrem A Production

Author: mycolabadmin
10/16/2025
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Summary

Researchers found that a mold called Penicillium crustosum produces a dangerous neurotoxin called penitrem A that can contaminate pears and other foods. The study showed that this mold grows best at cool temperatures (25°C) but produces the most toxin at slightly cooler temperatures (22°C) with neutral acidity and high moisture levels. Understanding these conditions helps us develop better strategies to prevent this toxin from contaminating the fresh fruit we eat.

Background

Penitrem A is an indole-diterpenoid neurotoxin produced by Penicillium crustosum and other Penicillium species on various food products including fruits, cereal grains, and dairy products. This emerging mycotoxin can cause severe neurological symptoms in humans and animals upon ingestion. Environmental factors such as temperature, pH, and relative humidity significantly influence fungal growth and mycotoxin production, yet much remains unknown about optimal conditions for P. crustosum penitrem A production.

Objective

This study isolated penitrem A-producing P. crustosum OM1 from pears and investigated the influence of temperature, pH, and relative humidity on its growth and penitrem A production. The researchers also analyzed the expression of six penitrem A biosynthetic genes under different culture conditions to understand the molecular mechanisms of toxin production.

Results

P. crustosum OM1 exhibited highest growth at 25°C and pH 4.5 on mYES4 medium under 98% relative humidity, while highest penitrem A production occurred at 22°C and pH 6.5 under the same humidity conditions. Four biosynthetic genes (ptmJ, ptmK, ptmO, ptmS) were significantly up-regulated in penitrem A-conducive medium (mYES4) but not in non-conducive medium (mMEB). Higher relative humidity (98%) was more favorable for penitrem A production than lower humidity (94%).

Conclusion

Temperature, pH, and relative humidity are key environmental factors that significantly affect both P. crustosum OM1 growth and penitrem A production, with distinct optimal conditions for growth versus toxin production. These findings provide important insights for developing control strategies to prevent penitrem A contamination in fresh fruits such as pears and other food products.

Published in:Journal of Fungi,
Study Type:Experimental Laboratory Study,
Source: PMID: 41149931, DOI: 10.3390/jof11100741