Kluyveromyces marxianus

Kluyveromyces marxianus is a species of yeast belonging to the kingdom Fungi, genus Kluyveromyces. While it is widely utilized in biotechnology and industrial fermentation, in the context of agronomy, it is identified as a facultative pathogen associated with post-harvest deterioration of various plant products.

This yeast primarily affects sugar-rich crops, including grapes, apples, tomatoes, and citrus fruits. The pathogen typically enters the plant tissue through mechanical wounds or physical lesions on the fruit surface. Once inside, it utilizes the carbohydrates present in the plant tissue for rapid growth, leading to biological degradation.

The biology of K. marxianus is defined by its remarkable thermotolerance. Unlike many other yeast species, it remains metabolically active at high temperatures, often exceeding 40°C. Development is accelerated in conditions of high humidity and sufficient simple sugars, allowing the yeast to colonize fresh produce rapidly within storage facilities.

The economic impact of this pathogen is significant due to the spoilage it causes in harvested produce. Infected fruits show signs of tissue softening, discoloration, and the development of off-odors, primarily related to fermentation byproducts. This renders the produce unfit for fresh market consumption and negatively affects long-term storage viability.

Control strategies focus primarily on post-harvest management and hygiene. Key protective measures include preventing physical damage to fruits during harvesting, ensuring rapid cooling to limit metabolic activity, and maintaining strict sanitation protocols for storage containers and facilities. Controlling humidity levels in storages is also a critical factor in inhibiting the spread of this yeast.