Intracellular Sulfur Inclusions: Source of Energy or Heater?

There are various groups of bacteria which receive energy from oxidation of inorganic sulfur compounds. Some of them produce elemental sulfur as an intermediate product and deposit it outside their cells. The group "sulfur bacteria" was described by their ability to produce intracellular sulfur inclusions. Traditionally, calculations of the released energy considered effect of the bacterial sulfide oxidation but never considered energy of the S-polymerization from monoatomic S to 8 atoms ring which is also essential (262.9 kJ). Till present, no biochemical reactions are known which could use energy of this eight atoms ring formation process. Thus, it is proposed that the intracellular sulfur inclusions can provide a lasting heating content of the cells as an additional advantage for the sulfur bacteria.