The communities of acidophilic chem olithotrophic microorganisms (ACM) are formed in sulfide ore deposits, mine waters, pyrite coals, the wastes of ore mining and processing industry in differ ent geographical and climatic zones, as well as in the pulps of reactors for the technologies of bacterialchemical oxidation of sulfide ore concentrates, i.e., in the presence of sulfide minerals and their oxidation products, elemental sulfur, reduced sulfur com pounds, and ferrous iron. As a result of their activity, the medium is acidified, sometimes to pH 0.5 or less, and the concentrations of heavy metals and toxic ele ments (copper, zinc, nickel, cobalt, arsenic, etc.) increase. These microorganisms therefore belong to extreme chemolithotrophic acidophiles. They include representatives of bacteria (both gram negative and gram positive) and archaea.Tables 1-3 present the best studied and most fre quently occurring ACM, the substrates they oxidize, and the ranges and optimal values of pH and tempera ture for their growth . It can be seen that some microorganisms can oxidize all inorganic substrates mentioned above, e.g., gram negative bacteria of the genus Acidithiobacillus (At. ferrooxidans, At. fer rivorans), gram positive bacteria of the genus Sulfoba cillus (S. thermosulfidooxidans, S. thermotolerans, S. benefaciens), and the archaeon Acidianus (Ac.) bri erleyi. Ferrous iron, elemental sulfur and sulfide min erals are used as energy sources by Metallosphaera sedula and M. prunae. Other microorganisms can obtain energy by oxidizing only ferrous iron or pyrite: Leptospirillum ferrooxidans, L. ferriphilum, and Ferro plasma acidiphilum. Most of the microorganisms (At. thiooxidans, At. caldus, and archaea) use elemen tal sulfur and reduced sulfur compounds as an energy substrate. The pH optima for the growth of these microorganisms are different, but all of them are in the range of acidic values. ACM live in a broad tempera ture range of 4 to 90°С. They include mesophiles with the optimal temperature for growth and oxidation of the energy substrate in the range of 28-35°С, moder ate thermophiles with the temperature optimum at 40 to 55°С, and thermophiles with the temperature opti mum above 60°С. The latter include mainly archaea. For instance, Ac. infernus has a temperature optimum for growth at 90°С [20].Abstract-The main representatives of acidophilic chemolithotrophs oxidizing sulfide minerals, ferrous iron, elemental sulfur, and reduced sulfur compounds and forming microbial communities in the natural and technogenic ecosystems with low pH values and high concentrations of heavy metal ions are listed. The spe cies and strain diversity of the communities and environmental factors affecting their composition (temper ature, pH value, energy substrate, mineralogical composition of sulfide ore concentrates, the presence of organic substances, and level of aeration) are analyzed. Involvement of mobile genetic elements (IS elements and plasmids) in the structural changes of the chromosomal DNA in the course of switching m...
