Mucor miehei

Mucor miehei (syn. Rhizomucor miehei) is a thermophilic filamentous fungus recognized primarily for its role in the post-harvest deterioration of agricultural products. Classified as a Zygomycete, this pathogen is well-adapted to high-temperature environments, which distinguishes it from many other common storage molds.

The fungus impacts a wide range of commodities, including stored grains, hay, silage, and oilseeds. It causes mucorales rot, a condition characterized by rapid hyphal expansion that consumes organic material, leading to significant quantitative and qualitative losses in agricultural supply chains.

The visual symptoms of an infestation involve the development of dense, cotton-like mycelium on the surface of the affected material. Initially appearing white, the colony turns grayish or brownish as it produces sporangia. Chemically, the fungus releases extracellular enzymes, such as lipases and proteases, which degrade the nutritional quality of the substrate and generate foul odors.

Environmental conditions are the primary drivers of Mucor miehei outbreaks. It thrives in high-temperature settings, especially those between 30°C and 50°C. In practice, this means that moisture-laden grain heaps that undergo spontaneous heating are highly susceptible to colonization, as the heat generated by biological activity favors the pathogen's optimal growth range.

Effective prevention and control strategies focus on rigorous post-harvest management. Key tactics include drying harvested crops to a safe moisture level, ensuring adequate aeration to prevent the "hot spots" that act as breeding grounds, and maintaining sanitary conditions in storage facilities through regular cleaning and the application of approved fungicidal treatments.