The phylum Thermotogae is composed of Gram-negative staining, anaerobic, and mostly thermophilic and hyperthermophilic bacteria. Acidilobus saccharovorans is a thermoacidophilic (that is, both thermophilic and acidophilic) species of anaerobic archaea. The nest heat results from the respiration of thermophilic fungi and other microorganisms. It was identified as an especially useful gelling agent in culturing thermophilic microorganisms. Due to its C4 photosynthetic system, proso millet is thermophilic like maize. Thermus is a genus of thermophilic bacteria. Yogurt, milk fermented by thermophilic bacteria, mainly"Streptococcus salivarius" ssp. The bacteria are acidophilic, thermophilic, and produce endospores. One use of vinasse is in thermophilic digesters. Composting toilets greatly reduce human waste volumes through psychrophilic, thermophilic or mesophilic composting. The Yellowstone hot springs are important for their diversity of thermophilic bacteria. The maximum temperatures tolerated by certain thermophilic arthropods exceeds the lethal temperatures for most vertebrates. The optimal temperature for thermophilic bacteria was placed even lower, around . Mesophilic systems are, therefore, considered to be more stable than thermophilic digestion systems. There are two key processes&colon; mesophilic and thermophilic digestion which is dependent on temperature.