Microbial metabolism: Please explain the three yeast behaviors based on modern conepts

» NealC - Please explain the three yeast behaviors based on modern conepts

Please explain the three yeast behaviors based on modern conepts of microbial metabolism.

Less suger was used per gram of organism when the organisms grew in oxygen because more ATP could be generated. Anaerobically grown organisms only breakdown the sugar via glycolysis and can not use the TCA cycle and the electron transport chain to generate more ATP. Aerobically grown organisms can utilize the TCA and ETC portions of their degradation pathways and generate much more ATP. ATP is the energy the cells use to produce protein, DNA, etc. in order to grow and multiply. More ATP=more yeast cells.

Aerobically grown yeasts given only protein for a carbon source can breakdown the protein to amino acids but require a functioning TCA cycle and an ETC to generate ATP. When the yeast cells are grown anaerobically the TCA cycle and ETC do not work and as a result no energy and no growth of anaerobically grown yeast with protein as a carbon source.

What was incorrect about Pasteur's conclusion?
It wasn't how the oxygen was obtained that allowed the growth of the organisms. It was the ability of aerobically grown organisms to further reduce the sugars to carbon dioxide and water that results in more ATP generation. More ATP more cell mass.

-- posted by NealC