The generated metabolic heat has to be removed from the bioreactor the temperature must be controlled for optimal cell growth. The yield of biomass produced per gram of oxygen consumed is:Ĭells utilise energy from substrate in an efficient way, like a real chemical process. The yield of biomass on glucose is calculated as follows: Based on definition, the yield of biomass on glucose means how much biomass is produced per gram of glucose utilised in a cell. Like any actual process, energy retained in the substrate is released as heat.įrom the above biomass production, calculate the yield coefficients. How many moles of ethanol were in the waste product stream? The overall biological reaction is summarised as:ĪC 6H 12O 6 bH 2O cCH 3CH 2OH 10CH 3CH(OH)COOHĬells are able to utilise chemical energy very efficiently.
The problem was adjusted by pH control and restarting the process without any contamination. No other products except ethanol were formed. It was expected that sugar was oxidised, then converted to pyruvic acid, then proceeded though the Embden–Meyerhof–Parnas pathway. The product stream was analysed as follows: lactic acid 10 moles, acetic acid 5 moles, carbon dioxide 15 moles and hydrogen 10 moles. The technician ran the equipment was experimentally but he forgot to weigh the glucose carbon source and did not analyse for ethanol. The dean of the school wished the equipment to be used for undergraduate students to learn about bioprocess concepts. There was an old and outdated fermenter in our school warehouse. Glyconeogenesis in the Embden–Meyerhoff–Parnas pathway. In this pathway the six-carbon substrate yields two three-carbon intermediates, each of which passes through a sequence of reactions to the stable end product of pyruvic acid.į IG. This is known as the glucose catabolism pathway, with emphasis on energetic and energy carrier molecules such as ATP, ADP, NAD and NADH. Reactions involve several enzymes, which have to follow in sequence for lactic acid and alcohol fermentation. The overall reaction of glucose catabolism to lactate and acetate fermentation from 2 moles of glucose yields 2 moles of lactic acid, 3 moles of acetic acid and 5 moles of ATP, as shown below:ĢC 6H 12O 6 2 lactic acid 3 acetic acid 5 ATP The fermentation pathways from pyruvate and the resulting end products are shown in Figures 9.7 and 9.8. The end pyruvate may go to lactate or be converted to acetyl CoA for the tricarboxylic acid (TCA) cycle. The pathway involves many catalysed enzyme reactions which start with glucose, a six-carbon carbohydrate, and end with two moles of three carbon intermediates, pyruvate. The metabolic pathway for bacterial sugar fermentation proceeds through the Embden– Meyerhof–Paranas (EMP) pathway. Therefore the exact stoichiometric coefficients for the above reaction are:Ĭ 16H 34 12.5O 2 2.13NH 3 10.63CH 1.66O 0.27N 0.2 5.37CO 2 11.4H 2O BIOCHEMICAL ENGINEERING AND BIOTECHNOLOGYĬ balance: 16 c d d 16 c H balance: 34 3 b 1.66 c 2 e
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