A simple question about amoeba (Naegleria fowleri)
I have studied somewhere that Naegleria can turn into cyst forms when the environment or the atmosphere becomes harsh to protect itself.


This is true, and can happen for a multitude of reasons, including extreme temperature (hot or cold), lack of food, and overcrowding.


  Is it possible for Naegleria to survive boiling temperature if the water is boiled for 15 minutes at 100 degree celcius by converting into cyst form and enter the nose of human and kill the human? 


In short: no, this is not possible. According to a publication by the Environmental Research Center, &amp; U.S. Environmental Protection Agency: 


  At 51, 55, 58, 63, and 65°C, Naegleria survived about 30, 10, 5, 1, and &lt;0.5 min, respectively.




That being said, just by going off the figures from the publication, there's no chance that Naegleria would survive for 15 minutes in 100°C boiling water.