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Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH. [ABSTRACT FROM AUTHOR]

Biological control of gastrointestinal nematodes is an alternative to chemical parasitic treatments. Nematophagous fungi can be developed as biological control products for gastrointestinal nematodes due to their capacity to produce traps that capture nematodes. Nevertheless, the lack of knowledge regarding the mass production of chlamydospores limits the production of biological products as alternatives to traditional antihelminthics. This study evaluated single and bi-phasic fermentation systems with three fermentation subsystems (entire grain, milled grain with low water content and milled grain with high water content) and four substrates (rice, barley, corn, and wheat), on the chlamydospores production of the nematophagous fungus Duddingtonia flagrans. The highest chlamydospores concentration was achieved using a bi-phasic fermentation system with rice as a substrate with a solid fermentation subsystem, which produced 2.01 × 108 chlamydospores g−1 after 14 days of fermentation. [ABSTRACT FROM AUTHOR]