The role of environmental factors in the conidiation of the predacious rotiferovorous fungus Zoophagus insidians (Zoopagomycota)

Abstract

Compared to other groups of fungi, the knowledge of freshwater predacious fungi that feed on trapped rotifers and tardigrades is very limited. They are known to spread and survive under adverse conditions by releasing asexual spores (conidia), but the environmental factors that induce their conidiation are unclear. In this study, we investigated the conidiation of the rotiferovorous fungus Zoophagus insidians isolated from activated sludge and maintained under laboratory conditions in spring water (medium). We found that its conidiation can undergo significant changes in response to various environmental factors, such as medium exchange, presence or absence of prey, lighting conditions, and their combination. Our results revealed a surprisingly high flexibility of this obligate predacious fungus, which being constantly exposed to unpredictable availability of prey in an unstable environment is still able to survive and disperse. • Zoophagus insidians produces conidia after approximately 6 days of development. • Non-fed mycelia produce more conidia than fed once. • Intense conidiation can be triggered in fed mycelia by medium exchange. • The effect of medium exchange becomes stronger under constant lighting conditions. • Blue light significantly increases the conidiation of Z. insidians.