Made mostly of collagen, bone is living, growing tissue. Collagen is a protein that provides a soft framework, and calcium phosphate is a mineral that adds strength and hardens the framework. This combination of collagen and calcium makes bone strong and flexible enough to withstand stress.
Psychrotrophic bacteria are defined as those that grow at 7Â°C, although their optimal growth temperature is higher. During cold storage after milk collection they dominate the flora, and their extracellular enzymes, mainly proteases and lipases, contribute to the spoilage of dairy products.
The low pH of highly acidic environments in volcanic areas and environments associated with metal ore mining is caused by the activities of acidophilic microorganisms that oxidize reduced sulfur compounds to sulfuric acid. Acidophilic microorganisms are found in all three domains of life: Archaea, Bacteria and Eucarya. Unicellular eukaryotic green algae such as Dunaliella acidophila and Chlamydomonas acidophila perform photosynthesis at pH values down to 0â1 and the red alga Cyanidium caldarium.