Document Detail

Effect of feed zone in fed-batch fermentations of Saccharomyces cerevisiae.
MedLine Citation:
PMID:  18601109     Owner:  NLM     Status:  PubMed-not-MEDLINE    
In production-scale, fed-batch fermentations, feed is often added to a single point at the top of the fermentor, which, combined with poor mixing, results in formation of a "feed zone" rich in nutrients. Frequent exposure of the culture to high concentrations of nutrients in the feed zone for sufficient duration can produce unexpected effects on its performance. The effect of the feed zone was evaluated by conducting aerobic fed-batch fermentations of Saccharomyces cerevisiae with both complex and defined media. The broth was recirculated between a recycle loop and a bench-scale fermentor, and feed was intermittently added into the recycle loop to simulate the circulation of cells through the feed zone. Experiments were carried out for a range of residence times in the recycle loop from 0.5 to 12 min. Biomass yields from the complex-media fermentations were not affected by exposure to high nutrient levels in the recycle loop for residence times up to 12 min. Ethanol consumption was reduced by as much as 50% for residence time in the loop up to 3 min. Very long exposure of yeast cells to excess nutrient levels (12 min) gave acetic acid formation. In a defined medium, the simulated feed zone effect increased biomass yield by up to 10%, but had no effect on ethanol levels. This study indicates that the feed zone effect on biomass yield in yeast fermentation, using complex substrates, will be negligible under fully aerobic conditions.
P K Namdev; B G Thompson; M R Gray
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biotechnology and bioengineering     Volume:  40     ISSN:  0006-3592     ISO Abbreviation:  Biotechnol. Bioeng.     Publication Date:  1992 Jun 
Date Detail:
Created Date:  2008-07-08     Completed Date:  2009-12-14     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7502021     Medline TA:  Biotechnol Bioeng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  235-46     Citation Subset:  -    
Department of Chemical Engineering, University of Alberta, Edmonton, Alberta, Canada.
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