Alternative substrates, growth

The metals copper, chromium and cobalt also appear to be essential for growth for some, if not all, microorganisms.1218 Cobalt is an essential requirement for cobalamin-utilizing bacteria, but apart from being an alternative substrate for an Mg2+ transport system, there appears to be no highly specific transport system for Co2+. E. coli has a high affinity uptake system for cyanocobalamin, even though it does not require Bl2. Cobalamin may thus serve as a source of cobalt. 

The respiratory systems of bacteria are of especial interest1435 and complexity in view of their ability in some cases to use alternative substrates as terminal electron acceptors, depending upon the environmental conditions. This will be illustrated with reference to E. coli, which has been reviewed recently.1436 The advantage of studying respiration in this organism is that, by choice of growth conditions, the pathways of electron transport can be manipulated. In addition, mutants are available which are defective in certain respiratory components. 

Also, the growth and the PHA accumulation on wastes and by-produets have been paid important attention in recent years, in order to enhanee the eeonomie and sustainable efficiencies. Thus, different alternative substrates were tested - such as vinasse, oil palm frond juice, soybean oil, waste glyeerol and other by-products from the biodiesel industry.Unfortunately up to now these strategies have not shown comparable productivities as an artificial carbon source (only 67.2 g of PHB were produced when soybean oil was used as a substrate). 

Wood remains one of the most versatile, durable and aesthetically pleasing substrates of all building materials. Whilst there have been trends in the growth and utilization of alternative substrates such as UPVC, wood continues to find favour in many applications including both structural and decorative end uses. 

Alternatively, graphene growth is also achieved by annealing giCi26.i27 HC 2 substrates at high temperatures... 

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