New research finds anti-fungal blend decreases mould spores

A new study conducted by Selko and Westerdijk Fungal Biodiversity Feed Institute has confirmed that the survival and development of Aspergillus chevalieri conidia was significantly decreased in the presence of an anti-fungal blend.

Selko, the feed additives brand of Nutreco, has uncovered insights that confirm the anti-fungal mode of action in a synergistic blend used in grain and animal feed preservation. In experiments conducted at Westerdijk Fungal Biodiversity Institute, in the Netherlands, scientists isolated Aspergillus chevalieri from moulded feed originating from different continents and countries. Researchers used Aspergillus chevalieri, a xerophilic mould which grows under low water activity (aW), as a model to evaluate how the synergy between organic acids (Fylax with Actiprop®) affected the mould’s fungal survival structures, including the ability of mould spores (conidia) to germinate and grow.

Pedro Caramona, Category Lead Feed Safety & Quality at Selko, remarked on the significance of the research for animal feed production. “We have continuously strived to improve the precision of our models to be able to confirm the mode of action of ActiProp in actual field conditions,” he said. “By further developing a statistically valid model, we can detail the mould’s growth kinetics, cell metabolism and development; providing a deeper understanding of the mode of action within the spore confirmed by electron microscopy imagery.” A scientific paper expanding on this work will be published in the International Journal of Food Microbiology later this year.

The anti-fungal properties of propionic acid have long been used as a preservation step in grain and animal feed production. However, according to Selko’s statement, the application of a single acid may not be as economically viable as perceived. Propionic acid is quite volatile, and its long-lasting effect can be compromised. The company points out that buffering with an ammonium agent supports a more effective application, reducing its corrosive proprieties and supporting safer handling.

Westerdijk Fungal Biodiversity Feed Institute, home to the world’s most diverse fungal collection, together with scientists from Selko conducted a series of experiments that looked at how a combination of ingredients in an anti-fungal blend (Selko’s Fylax Forte HC with ActiProp technology) affected germinating conidia, and subsequent germ tubes and hyphae. Selko shared details of the experiments: Light microscopy was used to count the colonies that developed. Fungal colonies from isolated conidia germination and growth were accessed for the different treatments using the oCelloscope™.

Results showed that the survival and development of Aspergillus chevalieri conidia was significantly decreased in the presence of Fylax with ActiProp, compared to a control group. The anti-fungal blend was demonstrated to significantly reduce the ability of hyphae (fungal cells) to grow compared to a control group (Table 1).

Fluorescence live-dead staining conducted on hyphae showed the percentage of cells that were significantly stained after cells were exposed to the feed additive blend at two different concentrations, and a control group. Significantly more cells were damaged after incubation with the blend at both concentrations compared to the control (Table 2).

Actiprop interferes with critical processes involved in energy production and ATP synthesis. Electron microscopical imagery of untreated and treaded conidia reveals the active ingredient’s ability to affect the cell membrane integrity and exert a disrupting effect particularly on the mitochondria, inhibiting spore germination, growth, and preventing spores to germinate.

“The ability to isolate conidia in animal feed, study its metabolism kinetics, reflects the commitment to innovation Selko is bringing to further science, and understand the effectiveness of our solutions on grains and feed preservation in support of a safer feed to food chain,” concluded Caramona.