Stimulating Duddingtonia flagrans chlamydospore production through dehydration

Abstract

Duddingtonia flagrans is a nematode-trapping fungus that has shown promising results as a tool to combat parasitic nematode infections in livestock. The fungus interrupts the parasitic lifecycle by trapping and killing larval stages on pasture to prevent reinfection of animals. One barrier to the fungus' commercial use is scaling up production of the fungus, and specifically of chlamydospores, which survive the digestive tract to grow in fecal pats on pasture, thus have potential as a feed through anthelmintic. The purpose of this study was to evaluate the effect of dehydration on sporulation of the fungus. Disks of Duddingtonia flagrans type strain (ATCC® 13423™) were grown on 17% cornmeal agar for 26 days at 30°C, then split into three groups; dried quickly at 38°C and 37% humidity over 48 h ("incubated"), dried more slowly at 24°C and 55% humidity over 10 days ("air-dried"), or kept at 30°C and sealed with parafilm to prevent loss of moisture as a control ("wet"). Half of each dried culture was resuspended in water, then heated to liquify and homogenized through vortexing. Spores were then counted in a Neubauer hematocytometer. Both the "air-dried" and "incubated" drying techniques yielded significantly more spores than the "wet" control (Welch's two sample t test p values of .0359 and .0411, respectively). The difference in average chlamydospores per milliliter was insignificant between the two drying techniques, although a visual representation of the data shows less spore count variability in the "air-dried" technique.

Chlamydospore dormancy and predatory activity of nematophagous fungus Duddingtonia flagrans

“…In summary, the cultivation time of D. flagrans during the growth process is positively correlated with chlamydospore yield and negatively correlated with germination rate. There are reports that the drying of D. flagrans cultures can significantly increase the production of chlamydospores, which is consistent with current research [5]. The key factor affecting spore dormancy is dehydration, so drying can accelerate spores into structural dormancy.…”

“…Nematophagous fungi Duddingtonia flagrans are recognized worldwide as agents for the biological control of animal parasitic nematodes [1][2][3][4][5]. Throughout its growth period, this fungus species can produce many chlamydospores formed from swelled mycelium after it matures and spherical or subglobose much larger than conidia.…”

In vitro evaluation of physicochemical variables on the nematophagous fungus Duddingtonia flagrans

“…Furthermore, the use of anthelmintics is also associated with the destruction of soil macrobiota and leaving traces in meat and milk products [3]. For these reasons, biological control by nematophagous fungi such as Duddingtonia flagrans is an attractive alternative to integrated management of these problems [1,4]. The mechanism of action of D. flagrans involves the passage of its reproductive structures (conidia and chlamydospores) through the gastrointestinal tract of its host.…”

“…The control of gastrointestinal nematodes in ruminants is carried out with anthelmintic drugs approved for veterinary use; however, anthelmintic resistance in nematode populations has been increasing around the world [1,2]. Furthermore, the use of anthelmintics is also associated with the destruction of soil macrobiota and leaving traces in meat and milk products [3].…”