| Popis: |
It is probable that compounds are accumulated in bacteria which function primarily as energy reserves. The majority of these may also act as carbon reserves and one, polyphosphate, as a phosphate reserve. As summarised in Fig. 8, if an exogenous utilisable carbon and energy source is present, there will be a synthesis of storage compounds, together with other essential cell components. However, in the absence of an exogenous carbon and energy source, storage compounds are broken down. If the concentration and rate of breakdown of the compounds is sufficiently high, utilisable energy and carbon intermediates accumulate at such a rate that a net synthesis of essential polymers (e.g. proteins, nucleic acids) may occur. More often, the rate of breakdown is only sufficient to prevent or minimise a net breakdown of essential polymers and to provide energy for other purposes essential for the maintenance of the species (adaptation, motility, sporulation etc.). In bacteria, the main energy-storage products are probably the following: (1) Intracellular polysaccharide, probably mainly homoglycans, e.g. glycogen. (2) Poly-β-hydroxybutyrate accumulated in lipid granules. (3) Other lipids such as triglycerides, possibly also accumulated in lipid granules. (4) Polyphosphate accumulated in volutin granules and subserving a special function in cell division. |
