The masseter muscle, which is one of the muscles used for chewing and is located in the jaw, is often considered one of the most powerful muscles in the human body in terms of its force and capability. However, the term "most powerful" can be interpreted in different ways, considering factors like strength, endurance, or speed. Different muscles might be considered the most powerful depending on the specific criteria used.

1. Kala-azar disease is caused by the protozoa Leishmania donovani.

2. It is a parasitic protozoa that belongs to the class Mastigophora or Flagellata. It is caused by sand fly (Phlebotomus) which causes kala azar or dumdum fever.

Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen.