WORKSHEET 2, MICROBIAL CELL CULTURE, CLASS12

 

1. What are the essential steps involved in the isolation of vitamin B12 from the microbe?
2. How will you go about studying the genomes of microbes that are uncultivable?
3. Why is it important to measure growth kinetics of microbial cultures? Name three different methods and highlight the one you think is most effective.
4. Why the pH of the culture medium is important? In a large fermenter, how is the pH maintained?
5. Why is oxygen important in fermenters and how is this provided?
6. What parameters must be monitored and controlled in an optimized fermentation process? Why do we need to control them?
7. Microbial culture procedures can be carried out in desired vessel in different ways. What are these different ways?
8. Why is it generally necessary to improve microbial strains before they can be used for mass production of a useful metabolite? Suggest a way to achieve it.
9. Why is strain preservation important in microbial cell culture? Give any two methods of strain preservation.
10. Plot a graph of the variation of cell density[X], concentration of substrate [S] and cell specific substrate turnover rate [QS] vs time for a batch culture and fed batch culture.
11. As a biotechnologist, what strategy will you suggest to your friend to enhance microbial growth while culturing microbes in the laboratory in a 50ml conical flask?
12. Draw flow chart to show steps for the isolation of an extracellular metabolite from microbial culture, using an example.
13. In a pilot experiment, it was found that CHO cell lines expressed EPO as 100mg/500ml of culture medium. A biotech company has to produce 500g of this protein. They have two 50L fermentors each, which can operate only once per week. How much time will it take to produce the desired amount of protein?
14. All microbes do not produce the substance of our interest and even when they are secreting the amount produced is low. How we find them and make them useful for us?
15. Recombinant insullin is produced at 100mg/l by E.coli at a cell concentration of 1g/l. Calculate the volume of reactor needed for producing 1Kg of insu;lin when the cell concentration is 50g/l and insulin production is 200mg/g of cells.
16. Write a short note on the ethical issues in microbial culture technology.
17. What is fed-batch culture and what are its benefits in microbial technology? How is it different from a batch culture?
18. Highlight graphically the differences between culturing microbes in the school laboratory and a bioreactor which allow cells to grow in a continuous culture system .
19. State any three advantages of using Pichia pastoris as a eukaryotic expression host.
20. Execute the engineered biosynthetic pathway which leads to the production of valuable secondary metabolites for their overproduction.
21. Fermentors are provided with many controls for the monitoring of physical, chemical and biological parameters that affect the growth cells. For this one is the sparger for aeration. What is its benefit?
22. (a) What is downstream processing? (b) Outline the steps to purify an antibiotic that is secreted into the growth medium.
23. (a) Assume 1ml of curd has 1X 107 cells of lactococci (spherical) of diameter 0.5 micrometers each. Calculate: (i) The number of lactococci in 500ml of curd (ii) The packed cell volume occupied by these lactococci (b) How would you ensure that the production of a recombinant molecule does not occur until required?
24. (a) Calculate the generation time of a bacterial population in which the number of bacteria increases from 104 / ml to 107/ml furing four hours of exponential growth. (b) Explain any two methods of measuring microbial growth. (c) In which phase of growth is the specific growth rate of microbial cells calculated? On what factors does the specific growth rate depend?
25. Recombinant insulin is produced at 100 mg/L by E. coli at a cell concentration of 1 g/L. Calculate the volume of reactor (size of the fermentor) needed to produce 1 Kilogram of insulin in the following conditions: (a) When the cell concentration is 1 g/L and insulin production is 100 mg/L. (b) when the cell concentration is 50 g/L and insulin production is 100 mg/L.