Mycetozoal bloom in a hydroponic culture of garden cress (Lepidium sativum L.)

The role and importance of the true slime moulds (mycetozoans, Mycetozoa, formerly Myxomycetes) for agriculture and food industry are poorly documented, most probably because of a low popularity of these “macroscopic microorganisms” among researchers in the past. Here we report probably for the first time the massive occurrence of true slime moulds in their vegetative, plasmodial form in a product intended for direct consumption, i.e. in a household hydroponic culture of garden cress (Lepidium sativum L.). The plasmodia gradually produced numerous, stalked or sessile sporangia and plasmodiocarps, which made it possible to identify them as Didymium species complex (the stalked sporangia) and Didymium difforme (Pers.) Gray (the sessile sporangia and plasmodiocarps). The mycetozoans were transferred to in vitro culture where they were maintained for several weeks on oat flour. We briefly discuss the importance of this observation from the point of view of biochemical interactions between the plant and the true slime moulds in a general context of slime mould biology. Our observation indicates that the presence of mycetozoan material in food products may be frequent, while its influence on food safety and quality remains unknown.

Research Highlights
► Spontaneous occurrence of mycetozoans in hydroponic culture of garden cress.
► Several species of Didymium develop on sprouting seeds.
► A new antropogenic habitat for mycetozoans.
► A new type of microbiological threat to food.
► A model to study the role of slime moulds in ecosystems.