Korean J Parasitol.  2017 Jun;55(3):233-238. 10.3347/kjp.2017.55.3.233.

Efficient Liquid Media for Encystation of Pathogenic Free-Living Amoebae

  • 1Department of Microbiology, Ajou University School of Medicine, and Department of Biomedical Science, Graduate School of Ajou University, Suwon 16499, Korea. hjshin@ajou.ac.kr
  • 2Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea.
  • 3Department of Biomedical Laboratory Science, Molecular Diagnostics Research Institute, School of Health and Medicine, Namseoul University, Cheonan 31020, Korea.


Pathogenic Naegleria fowleri, Acanthamoeba castellanii, and Acanthamoeba polyphaga, are distributed worldwide. They are causative agents of primary amoebic meningoencephalitis or acanthamoebic keratitis in humans, respectively. Trophozoites encyst in unfavorable environments, such as exhausted food supply and desiccation. Until recently, the method of N. fowleri encystation used solid non-nutrient agar medium supplemented with heat-inactivated Escherichia coli; however, for the amoebic encystment of Acanthamoeba spp., a defined, slightly modified liquid media is used. In this study, in order to generate pure N. fowleri cysts, a liquid encystment medium (buffer 1) modified from Page’s amoeba saline was applied for encystation of N. fowleri. N. fowleri cysts were well induced after 24 hr with the above defined liquid encystment medium (buffer 1). This was confirmed by observation of a high expression of differential mRNA of nfa1 and actin genes in trophozoites. Thus, this liquid medium can replace the earlier non-nutrient agar medium for obtaining pure N. fowleri cysts. In addition, for cyst formation of Acanthamoeba spp., buffer 2 (adjusted to pH 9.0) was the more efficient medium. To summarize, these liquid encystment media may be useful for further studies which require axenic and pure amoebic cysts.


Naegleria fowleri; Acanthamoeba castellanii; Acanthamoeba polyphaga; encystation; encystment medium
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