Nutritional Requirements in Fermentation Processes

Organisms that use CO2 as the principal carbon source are defined as autotrophic organisms that use organic compounds as the principal carbon source are defined as heterotrophic. A combination ofthese two criteria leads to the establishment of four principal categories (i) photoautotrophic, (ii) photoheterotrophic, (Hi) chemoautotrophic and (iv) chemoheterotrophic organisms. 

Since photosynthetic organisms (and chemoautotrophes) are the only net producers of organic matter on earth, it is they that ultimately provide, either directly or indirectly, the organic forms of energy required by all other organisms. 

Compounds that serve as energy carriers for the chemotrophs, linking catabolic and biosynthetic phases of metabolism, are adenosine phosphate and reduced pyridine nucleotides (such as nicotinamide dinucleotide or NAD). The structure of adenosine triphosphate (ATP) is shown in Fig. 1. It contains two energy-rich bonds, which upon hydrolysis, yield nearly eight kcal/mole for each bond broken. ATP is thus reduced to the diphosphate (ADP) or the monophosphate (AMP) form. 

Plants and animals can use the conserved energy of ATP and other substances to carry out their energy requiring processes, i.e., skeletal muscle contractions, etc. When the energy in ATP is used, a coupled reaction occurs. ATP is thus hydrolyzed. 

Biochemically, energetic coupling is achieved by the transfer of one or both of the terminal phosphate groups of AMP to an acceptor molecule, most of the bond energy being preserved in the newly formed molecule, e.g., glucose + ATP - glucose-6-phosphate + ADP.f  

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