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Published on: October 27, 2013
Efficient Liquid Media for Encystation of Pathogenic Free-Living Amoebae
Hae-Jin Sohn1, Heekyoung Kang1, Ga-Eun Seo1
1Department of Microbiology, Ajou University School of Medicine, and Department of Biomedical Science, Graduate School of Ajou University, Suwon 16499, Korea.
Abstract:
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.
Insights
Researchers developed a new liquid medium for inducing pure Naegleria fowleri cysts, improving upon older methods. This advance aids in studying these pathogenic amoebae and their related diseases.
Area of Science:
- Microbiology
- Parasitology
- Cell Biology
Background:
- Pathogenic amoebae like Naegleria fowleri and Acanthamoeba spp. cause severe human diseases.
- Amoebic encystment is crucial for survival in unfavorable conditions.
- Current methods for Naegleria fowleri encystment are suboptimal, often using solid media.
Purpose of the Study:
- To develop an efficient liquid encystment medium for Naegleria fowleri.
- To optimize cyst formation for Acanthamoeba spp.
- To provide pure, axenic amoebic cysts for research.
Main Methods:
- Modification of Page's amoeba saline to create a liquid encystment medium (buffer 1) for N. fowleri.
- Application of buffer 1 for N. fowleri encystation.
- Utilizing a modified liquid medium (buffer 2, pH 9.0) for Acanthamoeba spp. cyst formation.
- Confirmation of encystment via mRNA expression analysis (nfa1 and actin genes).
Main Results:
- A defined liquid encystment medium (buffer 1) effectively induced pure Naegleria fowleri cysts within 24 hours.
- High expression of nfa1 and actin mRNA confirmed successful encystment.
- Buffer 2 (pH 9.0) proved more efficient for Acanthamoeba spp. cyst formation.
- The new liquid media enable the generation of axenic and pure amoebic cysts.
Conclusions:
- A novel liquid encystment medium provides an improved method for obtaining pure Naegleria fowleri cysts.
- This method surpasses previous solid-media techniques for N. fowleri encystation.
- Optimized liquid media for both Naegleria and Acanthamoeba spp. will facilitate further research into these medically significant amoebae.
