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Title: Intensive propagation and utilization of lactic acid bacteria in membrane reactor
Author: Jung, I.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2006
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The main object of the project is to investigate the use of membrane cell recycle reactor (MCR) to grow lactic acid bacteria (LAB) to a high cell density and the possibility of using them for industrial application. Four lactic acid bacteria of Lactobacillus buchneri, L. Brevis, Oenococcus oeni, and Bifidobacterium longum were investigated in batch, pH-controlled stirred tank reactor (STR), and MCR culture. The cell mass of the four LAB during the culture in MCR reached a high concentration and was typically over 7 times that obtained in batch and pH-controlled STR culture. The cell production rates in the MCR were from 10 to 33 times greater than that in batch and pH-controlled STR culture, even though growth rates during the culture were lower in MCR than in batch and pH-controlled STR culture. Membrane fouling was significant limitation not only to growth of LAB at high growth rates, but also to increase of the final cell concentration attainable. High cell density cultures of L. Brevis and O. oeni were then used to study malolactic fermentation of cider in the MCR. The maldlactic strains showed a good tolerance in the extreme conditions such as low pH and high alcohol concentration (13%, w/v) of the green cider during the MLF in MCR.  Two ciders, general cider and pure apple juice cider (Scrumpy Jack), showed significant differences when subject to MLF of the LAB. The MLF of Scrumpy Jack by O. oeni was inhibited more than that of general cider. This project shows that MCR can grow LAB to high cell density and that high cell density transformation can be used to overcome significant problems at the traditional MLF processes. This technology is widely applicable to biotransformation of other foods and chemicals.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available