Production and modeling of probiotic Lactobacillus casei growth in batch and fed batch fermentation | |
| Author | Montalbo, Melissa T. |
| Call Number | AIT Thesis no.FB-04-04 |
| Subject(s) | Fermentation Lactobacillus casei |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. FB-04-04 |
| Abstract | Probiotic Lactobacillus casei growth in MRS media and modified GS media was studied in shake flask, batch, and fed batch fermentations with the aim of increasing biomass concentration that could be used in animal feed. In shake flask cultivation, the productivity and cell yield in modified GS media were 0.085 g/L-hr and 0.3197 g biomass I g glucose, respectively, which is higher than in MRS media with 0.066 g!L-hr and 0.1974 g biomass I g glucose, respectively. Lactobacillus casei is a facultative anaerobe that favors anaerobic condition but can still thrive in aerobic condition. The flushing of nitrogen in batch bioreactor and agar plates to give a strict anaerobic environment did not give much difference in terms of bacterial yield and productivity. With the different initial glucose concentrations in batch fermentation, the cell yield was 0.3237, 0.2972, and 0.1668 g biomass I g glucose in 2%, 4%, and 6% initial glucose concentrations, respectively. The highest productivity was achieved by 4% glucose at 0.117 g/L-hr. The specific growth rate drops at 6% glucose with 0.205 /hr. This shows that initial glucose higher than 4% will inhibits the cell growth. Hence, glucose concentration should not be higher than this level in bioreactor. The harvested cells in batch fermentation were kept in 4°C cold room for storage and evaluated its viability aHer 30 days. The number of viable cells was about 8.95-log cfu/ml with a death rate of 0.0883-log cfu/ml-per day. This is an important characteristic for effective use of pro biotic. In fed batch fermentations with pH controlled, higher productivity was achieved at 0.445 g/L-hr and a doubling time of 1.99 hours compared to a non-pH controlled. A higher maximum biomass of 13. 72 g/L in glucose fed-batch fermentation was achieved than Nitrogen Metal Sources (NMS) fed batch fermentation with 7.36 g!L. μmax was also higher in glucose than NMS deprived fermentation. Finally, a mathematical model was set up to simulate cell growth, glucose consumption, and lactic acid production. The model showed that bacterial growth was dependent on both the energy and the complex nitrogen source. It was also used to predict bacterial growth with increased level of glucose fed. With a model simulation, it was found that addition of up to 80 g/L glucose in a fed batch reactor could increase the enzyme productivity by 30% compared to a batch. With higher concentrations of glucose (240 g!L) and faster feed rates (0.02 Li/hr), the biomass productivity was only increased by 15%. Using the model simulations, the optimum condition to achieve a high cell density biomass of 34.458 g!L is obtained by a glucose feeding of 380 g!L and NMS feeding of 380 g!L at 0.0075 L/hr. The maximum overall glucose concentration added is 126.67 g/L. It is only in fed batch that such high concentration of glucose is used. |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. FB-04-04 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Rakshit, Sudip Kumar |
| Examination Committee(s) | Athapol Noomhorm; Jindal, Vinod K. |
| Scholarship Donor(s) | Katholischer Akademischer Auslander-Dienst (KAAD), Germany |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2004 |