Midterm

Question 1

what are the three traditional workers in the fermentation industry?

Answer 1

Bacillus (extracellular enzymes, antibiotics, insecticides), Aspergillus (citric acid exoenzymes used in food industry
biotransformations), Saccharomyces (yeasts, bioethanol
potential for other fine & bulk chemicals)

Question 2

Gram positive bacteria and gram negative bacteria

Answer 2

The gram positive bacteria secretes enzymes outside, but the gram negative bacteria may be periplasmic

Question 3

What is exponential equation for microbial growth?

Answer 3

dx/dt = μx - αx
where x = cell concentration (mg/mL)
t = incubation time (h)
μ = specific growth rate (h-1)
α = specific rate of lysis or endogenous metabolism (h-1)

Question 4

What happens in the microbial growth equation when μ»α?

Answer 4

td = ln2/μ

Question 5

What happens in the deleterious and stationary stage?

Answer 5

Deceleration phases and stationary phase, does not mean that cell division is not happening, just means that the dividing is happening at the same rate as death rate

Question 6

What are bacteria species grouped based on?

Answer 6

growth temperature range

Question 7

Define amphibolic, anapleroic reaction

Answer 7

1.) when a biochemical reaction has both catabolism and anabolism. 2.) To replace intermediates in the TCA cycles as some TCA intermediate molecules are important in biosynthesis such as amino acids. This ensures that the TCA cycle can still resume. Example: PEP combined with CO2 makes oxaloacetate

Question 8

What is the difference between primary and secondary metabolite?

Answer 8

Primary metabolite (often precursors ): produced as part of growth i,e ethanol from Saccharomyces cerevisiae
Secondary metabolite: Produced near of in stationary phase. not required for cellular biosynthesis; have no direct role in energy metabolism. Presumably have some advantage in natural environment. Often are family of vey closely related compunds i.e Penicillium chrysogenum produces a suite of very similar antibiotics but Penicillin G in most amounts

Question 9

Enzyme system subject to induction and repression. After enzyme is formed how are they regulated?

Answer 9

induction (small molecules - inducers i.e allolactose), bind to allosteric protein - conformational change leads disscaostes from operator and transcription starts. vs co-repressor (such as gaccumulation of amino acids) - same as above
isoenzymes, concerted and cumulative

Question 10

What is an example of enzyme modification?

Answer 10

covalent modifications alter protein conformation and regulates enzymatic activity (inhibit or enhance)
I,e adenylation of glutamine synthetase (Adding AMP)
glutamine synthetase when high glutamine, there will be high AMP which binds to glutamine synthetase to inhibit activity

Question 11

True or false: Prokaryotes are capable of endocytosis?

Answer 11

False - no membrane bound organelles

Question 12

Biomass concentration at time “t” in batch culture equation?

Answer 12

Biomass at time t :Y =( x - X)/ (SR - s)
When s = 0: Y = (x - XR)/(SR)

x = cell concentration at time “t”
XR = inoculum or initial cell concn
Y = yield factor for limiting substrate (g biomass/g substrate consumed)
s = substrate concn at time “t”
SR = original concn in medium

Question 13

Difference between turbidostat and chemostat in continuous system?

Answer 13

possible to run as turbidostat (μ = μmax); medium inflow controlled by culture turbidity (maintained constant)

possible to run as chemostat; where culture turbidity is controlled by one limiting nutrient in medium inflow, growth rate is controlled by rate at which new medium is introduced

Question 14

In a homogeneously-mixed continuous reactor (i.e., CSTR) what is equation at steady state?

Answer 14

Steady-state where formation of new biomass in culture is balanced by loss of cells from culture, & specific growth rate (μ) is controlled by the dilution rate (D)
D = F/V (Note volume should be constant and therefore D is controlled by F)
V = the volume (m3)
F = flow rate (m3 per h)

Question 15

True/False: once steady state is established at a given D, only a single value of “x” & of “s” is possible

Answer 15

True:
x (steady state biomass) is controlled by D and SR
x = Y [SR - KsD ]
μmax - D

s (stead state substrate conc) is controlled by D
s = KsD
μmax - D

Question 16

What are the two main types of mixing behaviour?

Answer 16

Newtonian - the viscosity of the culture is independent of shear force

non-Newtonian (several classes) - the viscosity varies with shear forces
fungus-containing broths can alter in apparent viscosity during growth
increasing viscosity affects bubble retention, gas transfer

Question 17

True/False: microbes capable of growing in minimal media generally grow much better in complex media

Answer 17

True

Question 18

What are the 6 criteria to consider when choosing feedstock?

Answer 18

cost; ready availability of material
transportation costs
post-production waste disposal issues
uniformity in raw material quality, ability to standardize
chemical composition of medium, presence of relevant precursors
regulatory limitations (e.g., FDA filing)
growth & production requirements of microbes

Question 19

Which type of feedstock would be suitable for high carb requirement and low N?

Answer 19

corn steep liquour (But have to neutralize) - by-product of starch production from corn; highly acidic (SO2 addition) → need to neutralize

Question 20

Which type of feedstock would be suitable for high protein and carb?

Answer 20

Distillers soluble - by-product of distillation of alcohol from fermented grain

Question 21

Which feedstock have precursor for forming penicillin?

Answer 21

corn steep liquour- penylethylamine

Question 22

Molasses feedstock used for?

Answer 22

molasses: by-product of sugar industry

used in production of potable & industrial alcohol, acetone, citric acid, glycerol, yeast biomass

Question 23

Define Respiration:

Answer 23

respiration: catabolic reactions producing ATP in which either organic or inorganic compounds are primary electron donors & organic or inorganic compounds are ultimate electron acceptors

Question 24

Define fermentation in terms of catabolism

Answer 24

catabolic reactions producing ATP in which organic compounds serve as both primary electron donor & ultimate electron acceptor; & ATP is produced by substrate-level phosphorylation

Question 25

Who invented the term Biotechnology? and fermentation biotechnology is what colour?

Answer 25

Karoly Ereky, white

Question 26

What are some other definitions of fermentation?

Answer 26

any process involving the mass culture of microorganisms, either aerobic or anaerobic. fermentation involves the use of microorganisms to carry out enzyme-catalyzed transformations of organic matter.
Includes the production of alcoholic beverages
food spoilage

Question 27

What was the key in glycerol production in ww1?

Answer 27

Bisulphite

Question 28

How does Bisulphite lead to glycerol production?

Answer 28

Prevents acetaldehyde production, and there is a build up of NADH and a lack of NAD+ . to fix the redox imbalance, the cell diverts the carbon flow to produce NAD+ with end product is glycerol

Question 29

Example of biotransformation to avoid deactivation of penicillin due to enzymatic hydrolysis of penicillin acylase ?

Answer 29

semi-synthetic penicillin
mass culture of fungus (P. chrysogenum) to produce PenG
mass culture of suitable bacterium to produce penicillin acylase
recover & purify enzyme → biotransformation protocols to produce semi-synthetic penicillins using 6-APA as “base” molecule

at pH 7.5-8.5: use enzyme to convert PenG to 6-APA

run reaction in reverse at acidic pH with suitable acyl donors present → produce semi-synthetic penicillins from 6-APA

Question 30

Which compound is the core of penicillin production?

Answer 30

6-APA is the core of penicillins- used as the main starting block for the preparation of numerous semisynthetic penicillins.