Microbial Ecology

, Volume 73, Issue 3, pp 699–709 | Cite as

Effects of Bacillus cereus Endospores on Free-Living Protist Growth

  • Susana S. Santos
  • Niels Bohse Hendriksen
  • Hans Henrik Jakobsen
  • Anne WindingEmail author
Host Microbe Interactions


We studied the predator–prey interactions between heterotrophic protists and endospores of Bacillus cereus group bacteria, in order to gain insight on survival and dispersal of B. cereus endospores in the environment. It has been hypothesised that the spore stage protects against digestion by predating protists. Therefore, experiments were carried out to investigate the impact of B. cereus endospores and vegetative cells, as the only food source, on individual amoeboid, flagellated and ciliated protists. The presence of fluorescent-labelled intracellular bacteria confirmed that B. cereus endospores as well as vegetative cells were ingested by protists and appeared intact in the food vacuoles when observed by epifluorescence microscopy. Furthermore, protist growth and bacterial predation were followed by qPCR. Protists were able to grow on vegetative cells as well as endospores of B. cereus, despite the lower cell division rates observed for some protists when feeding on bacterial endospores. Survival and proliferation of ingested bacteria inside protists cells was also observed. Finally, B. cereus spore germination and growth was observed within all protists with higher abundance in the amoeboid protist after antibiotic treatment of the protist surface. These observations support that protists can act as a potential breeding ground for B. cereus endospores.


Bacterivorous protist Food quality Growth rates Ingestion rates Predator–prey interaction Soil food web 



This research is part of the European project Trainbiodiverse and was funded by Marie Curie Actions. Authors would like to thank Inês Nunes for all the help and support during the RNA work and Tina Thane, Tanja Begovic and Pia Petersen for laboratory support.

Compliance with Ethical Standards

Funding Information

This work was supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. (289949) and the eDNA center supported by the Danish Centre for Environment and Energy at Aarhus University. HHJ received support from the VELUX foundation to procure microscopes and tools from epi-fluorescence microscopy grant no. (VKR022608).

Conflict of Interest

None declared.

Supplementary material

248_2016_905_MOESM1_ESM.docx (1.9 mb)
ESM 1 (DOCX 1.94 mb)


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Susana S. Santos
    • 1
  • Niels Bohse Hendriksen
    • 1
  • Hans Henrik Jakobsen
    • 2
  • Anne Winding
    • 1
    Email author
  1. 1.Department of Environmental ScienceAarhus UniversityRoskildeDenmark
  2. 2.Department of BioscienceAarhus UniversityRoskildeDenmark

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