Divalent metal cations potentiate the predatory capacity of amoeba for Cryptococcus neoformans

Man Shun Fu, Arturo Casadevall

Research output: Contribution to journalArticle

Abstract

Among the best-studied interactions between soil phagocytic predators and a human-pathogenic fungus is that of Acanthamoeba castellanii and Cryptococcus neoformans. The experimental conditions used in amoeba-fungus confrontation assays can have major effects on whether the fungus or the protozoan is ascendant in the interaction. In the presence of Mg2+ and Ca2+ in phosphate-buffered saline (PBS), C. neoformans was consistently killed when incubated with A. castellanii. A. castellanii survived better in the presence of Mg2+ and Ca2+, even when incubated with C. neoformans. In the absence of Mg2+ and Ca2+, C. neoformans survived when incubated with A. castellanii, and the percentage of dead amoebae was higher than when incubated without yeast cells. These results show that the presence of Mg2+ and Ca2+ can make a decisive contribution toward tilting the outcome of the interaction in favor of the amoeba. Of the two metals, Mg2+ had a stronger effect than Ca2+. The cations enhanced A. castellanii activity against C. neoformans via enhanced phagocytosis, which is the major mechanism by which amoebae kill fungal cells. We found no evidence that amoebae use extracellular killing mechanisms in their interactions with C. neoformans. In summary, the presence of Mg2+ and Ca2+ enhanced the cell adhesion on the surfaces and the motility of the amoeba, thus increasing the chance for contact with C. neoformans and the frequency of phagocytosis. Our findings imply that the divalent cation concentration in soils could be an important variable for whether amoebae can control C. neoformans in the environment.

Original languageEnglish (US)
Article numbere01717-17
JournalApplied and Environmental Microbiology
Volume84
Issue number3
DOIs
StatePublished - Feb 1 2018

Fingerprint

Cryptococcus neoformans
Amoeba
Divalent Cations
Acanthamoeba castellanii
cations
cation
Metals
fungus
metal
calcium
motility
adhesion
Fungi
yeast
soil
phagocytosis
Phagocytosis
phosphate
assay
predator

Keywords

  • Amoeba
  • Cations
  • Cryptococcus neoformans
  • Fungi
  • Predation

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

Divalent metal cations potentiate the predatory capacity of amoeba for Cryptococcus neoformans. / Fu, Man Shun; Casadevall, Arturo.

In: Applied and Environmental Microbiology, Vol. 84, No. 3, e01717-17, 01.02.2018.

Research output: Contribution to journalArticle

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