Spore heterogeneity of food spoilage fungi; Aspergillus niger, Penicillium roqueforti and Paecilomyces variotii

Sjoerd J. Seekles 1 Tom van den Brule 2 Maarten Punt 3 Jan Dijksterhuis 2 Jos A.M.P. Houbraken 2 Wieke R. Teertstra 3 Arthur F.J. Ram 1 Han A.B. Wösten 3
1Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden, Netherlands
2Applied and Industrial Mycology, Westerdijk Fungal Biodiversity Institute, Utrecht, Netherlands
3Microbiology, Department of Biology, Utrecht University, Utrecht, Netherlands

At the moment, a significant part of food spoilage and food waste can be attributed to fungal contamination and spoilage. Food preservation methods like sterilization and salt addition reduce spoilage enormously. However, consumers prefer minimal processing of food to maintain taste and nutritional composition, which leads to increased risk of fungal spoilage. Therefore, fungal food spoilage research is needed in order to promote new and enhanced food processing protocols.

Food production needs to increase by 70% to feed the world population in 2050. Reducing post-harvest food spoilage could significantly contribute to this challenge. At the moment, 25% of the food is spoiled, a significant part due to fungal contamination. Fungal food spoilage occurs in all food categories. For instance, Penicillium roqueforti and Paecilomyces variotii are important spoilage fungi of dairy products and pasteurized beverages, respectively, while Aspergillus niger is a known food spoiler of fresh fruits and vegetables.

Fungal food spoilage starts with contamination of food products with conidia. These asexual reproduction structures are abundant in the environment, making contamination inevitable. Minimal processing of these contaminated food products proves to be challenging. Experimental data strongly indicates the existence of subpopulations of conidia with different levels of resistance to preservation methods. The aim of this project is to study the extent of this heterogeneity and to study the underlying mechanisms using fungal model systems.

In these works, we will elaborate on this heterogeneity by investigating the impact of the genetic background (differences in strains), environmental conditions (differences in growth conditions), and the developmental state on preservation/stress resistance of Penicillium roqueforti, Paecilomyces variotii and Aspergillus niger conidia.