Cell Inclusions

 Inclusions are intracellular structures that serve as storage sites for nutrients, metabolic byproducts, or other compounds.

Excess carbon is often stored as poly-β-hydroxybutyric acid granules, composed of lipid polymers, or glycogen granules. These storage forms serve as carbon reservoirs and rapid energy sources when needed.

Metachromatic granules, or volutin, are polyphosphate granules commonly found in Corynebacterium. These granules store inorganic phosphate for nucleic acid and ATP synthesis.

Sulfur globules, an energy reserve for sulfur-oxidizing bacteria such as Thiobacillus, store elemental sulfur.

Some cyanobacteria produce carboxysomes, containing enzymes like RuBisCO, that facilitate carbon dioxide fixation.

Gas vacuoles are air-filled hollow structures that enable aquatic bacteria and archaea to maintain buoyancy, optimizing access to light and nutrients.

Magnetosomes, composed of magnetite or greigite, are found in bacteria such as Magnetospirillum magnetotactic. They align aquatic bacteria with the Earth’s magnetic field and guide them downwards towards anaerobic zones with low oxygen concentrations.