Download Industrial Microbiology 7.5 ECTS

Industrial Microbiology
Ladokcode:
The exam is given to:
7.5 ECTS
42K19C
Btma12
Name:
Personal number:
Date of exam:
Time:
12-10-23
9:00-13:00
Means of assistance:
Accepted aid/tool: Dictionary
NOT accepted aid/tool: Electronic dictionary
Total amount of point on exam:
85 points
Requirements for grading:
A= 76 points, B= 68 points, C= 52 points, D= 51 points, E= 42 points, F and FX < 42 points
Additional information:
Please, answer each one of the questions 6 - 9 on a new sheet of paper. Do not write on the back
side of the paper.
The results are for the most part posted within three weeks after the exam, otherwise it’s the following date:
Important! Do not forget to write your name on each paper you hand in.
Good Luck!
Examiner:
Phone number:
Elisabeth Feuk-Lagerstedt
0704-444188
Multiple Choices: Give the most correct answer for each of the following
questions 1- 5. (2 points each)
Question 1
Virions:
a. Can only be seen in a phase contrast microscope.
b. Can only be seen in a dark field microscope
c. Can only be seen in a light field microscope
d. Can only be seen in an electron microscope
e. None of above
Question 2
All organisms belonging to Bacteria are:
a. G+ cells
b. G- cells
c. G+ or G- cells
d. F+ cells
e. None of above
Question 3
The last step in gene expression is called:
a. Protein synthesis
b. Transcription
c. Replication
d. Mutation
e. None of above
Question 4
Which of the following statements is correct about phages?
a) Only infect gram positive bacteria
b) Cannot perform specialized transduction
c) Lack genetic materials
d) Have plasma membranes
e) None of above
Question 5
Which of the following statements is correct about Archaea?
a. Are all heat sensitive
b. Are virions
c. Lack peptidoglycan in their cell wall
d. Are all autotrophs
e. None of above
Please, answer each of the questions 6-9 on a new sheet of paper and do not
write on the back side 
Background:
Today, the global need for alternative energy sources is quickly growing. Biogas has many
advantages compared to other Biofuels because it can be produced from a wide range of
organic materials including many waste products like lignocellulose. To convert the organic
substrates by fermentation to biogas, synchronized processes take part under anaerobic
conditions. Together they involve a mixture of microorganisms and a wide range of enzymes.
The fermentative Thermoanaerobacterium thermosaccharolyticum is a good hydrogen
producing microorganism, which carries out the hydrolysis and acetogenesis lignocellulosic
material by forming products like acetate and buturate. Another organism that can be used for
hydrolysis of the same material is the fungus Trichoderma reseii. This organism excretes
large amounts of the enzyme cellulase during the process.
Some bacteria like Clostridium thermoaceticum produce acetate directly in the acidogenic
fermentation of sugars and volatile fatty acids while Syntrophobacter wolinii produces acetate
together with hydrogen and carbon dioxide during the acetogenic process.
Finally, archaeans like Methanobacterium formicicum and Methanobacterium barkerii
convert acetate, hydrogen and carbon dioxide into methane.
Question 6
a) Describe the six different microorganisms mentioned above in terms of Prokaryotic
and Eukaryotic. (6p)
b) Which of the microorganisms mentioned above has / have organelles? Give motive for
your answer! (4p)
c) Describe the differences and similarities in the cytoplasmic membrane structure of the
microorganisms mentioned above. (8p)
Question 7
Cellulase is not one enzyme but a system of exoenzymes with β-Glucosidase as an important
component. In T. thermosaccharolyticum this enzyme is encoded by the bgl gene and
expressed as a protein with 443 amino acids. Also some mutated strains of E. coli are able to
utilize glucosides and here the glucosidase enzyme is encoded by the bgl operon which
comprises the three genes, bglG, bglF, and bglB.
a) What is an exoenzyme? (2p)
b) Draw a sketch over the bgl operon in E. coli. (5p)
c) Explain the assumed regulation of the operon in E. coli. Give motive for your answer!
(8p)
d) Explain the transcription process and its end product. (6p)
e) Is the mutation in the bgl operon a selectable mutation? Give motive for your answer!
(3p)
Question 8
The fungi Aspergillus niger is also a good producer of cellulase and has been used for
industrial production. It produces both the endo-ß-glucanase (C1) and the exo-ß-glucanase
(Cx). A small scale production was done during 60 hours in a laboratory bioreactor (500 ml) at
35oC under aerobic conditions. Samples were taken every second hour. Below you can see the
biochemical outline for cellulase production from a medium containing cellulose as only
carbon- and energy source (supplemented with some glucose). The graph also shows the
accumulation of cellulase:
Cell Protein (mg/ml);
C1 activity (mUnits/ml;
Cellulose (mg/ml),
Cx activity (mUnits/ml)
a) Is cellulase a primary or secondary product? Give motive for your answer (5p)
b) What type of culture (batch or continuous) do you think they have used in this
experiment? Give motive for your answer. (4p)
c) Draw the growth curve for A. niger in this experiment. Explain the appearance of the
curve and also the method you would chose to estimate the number of cells. (10p)
d) Which is the largest advantage, in your opinion, to choose A. niger in stead of T. riseii
for industrial production of cellulase? Give motive for your answer! (4p)
Question 9
Two reasons, why the highly aerobic A. niger and the facultative anaerobic E. coli are good
organisms for industrial production, are the facts that they are unicellular and can be grown on
cheap media. As producers, they must be able to create energy. Describe where and in which
way A. niger and E. coli, respectively, produce energy. (10p)