Archaea

Archaea is a group of single-cell, microscopic organisms that have no nucleus or other membrane-bound organelles. They have many similar structural and metabolic features with bacteria, but they also have several critical differences. Many archaea and bacteria have a syntrophic relationship where they coexist and benefit each other in floc particles, biofilm, and sludge. Archaea that survive in low pH conditions are known as acidophiles, while those that survive in high pH conditions are known as alkalophiles. Sulfolobus is an example of an archaea that prefers high temperatures and extremely low pH. There are two major archaeal kingdoms with species that contribute to the stabilization of wastes: Crenarchaeota and Euryarchaeota. Crenarchaeota contains thermophilic organisms, acidophilic organisms, and ammonia-oxidizing archaea. Euryarchaeota contains halophilic organisms, thermophilic organisms, and methanogens. Archaea also have novel enzymes and metabolic pathways including sulfur pathways involved in a variety of dissimilatory and assimilatory forms of sulfur metabolism.