Industrial Microbiology Flashcards
What is the definition of an antibiotic?
Compounds of natural, semi-synthetic, or synthetic origin which inhibit growth of microorganisms without significant toxicity to the host
What do all penicillins have as part of their chemical structure?
Beta Lactam Ring (4 membered ring/square)
Why do antibiotics exhibit selectivity?
Due to the separation (by many years) between eukaryotic and bacterial life forms = different cell organization, biochemical pathways, and protein/RNA structures…
What needs to be true about the target of an antibiotic in order to ensure selectivity? [2 - one or other]
Target can be present only in bacteria but not eukaryotic host (eg: B-lactams vs. cell wall)
OR
Target in bacteria is different from the homologous target in host (bacterial vs eurkaryotic ribosome)
What are antibiotics used for naturally?
Why are many antibiotics omnipotent and inhibit growth of a wide range of microorganisms?
Defending vs other microorganisms
Microorganisms share common evolutionary origins and thus share biochemical targets
What are some of the possible targets of antibiotics?
+ folate biosynthesis (sulfonamides)
Is the bacterial cell wall essential for survival? What’s its purpose?
What makes it a good target for antibiotics?
Yes - it protects bacteria from changes in osmotic pressure
It is biochemically and structurally different from cell envelope of eukaryotes - as it is unique to bacteria, it makes for a great target
What is the bacterial cell wall made up from?
What are the major components of this material?
Cross-linked peptidoglycan
Alternating N-acetylgucosamine and N-acetylmuramic acid (sugars) cross-linked by 3-5 amino acids between N-acetylmuramic acids.
What is the name of the enzyme responsible for cross-linking peptidoglycan strands? When does it undertake this process? What does it lead to?
What type of antibiotic targets this enzyme? What does it do? What type of bond does it form with the enzyme? What is the result?
Transpeptidase (active during normal growth, leads to cell wall strength)
B-lactam antibiotics (penicillins) - it inhbits the enzyme (and forms a covalent bond - “suicide substrate” and irreversible), preventing cross-linking, and leads to cell wall weakness (and will rupture, killing the cell, under osmotic pressure).
Why do B-lactam antibiotics have the effect they have (weakening cell wall and leading to rupture)?
The B-lactam ring of the antibiotic is similar to the peptide bond connecting two D-alanine resides of the peptidoglycan precursor. Transpeptidase (cross-linking enzyme) recognizes the antibiotic as its substrate, and forms a covalent bond with it, thus irreversibly inactivating the enzyme and failing to create cross-links
Who discovered antibiotics?
Who developed methods for growing and purifying penicillin (making it into a drug)?
What did Mary Hunt discover that made commercial production of penicillin possible? What was the original issue?
Alexander Fleming
Howard Florey and Ernst Chain
P. chrysogenum (penicillin notatum didn’t produce enough to make it viable)
Bacterial-produced antibiotics…
Which one produces over two thirds of clinically useful antibiotics of natural origin? Examples?
Clavulanic acid is produced by S. clavuligerus. What is it used in combo with? Why?
Streptomyces (neomycin, cypermycin, grisemycin, bottromycins, chloramphenicol)
Used w/beta lactams to block/weaken bacterial resistance mechanisms caused by beta-lactamase enzyme
Most antibiotics are termed _________ metabolites. What does this mean?
Considering this, what are the types of culture used to produce them?
Secondary - produced in large quanities only towards the end of batch growth (end of exponential growth phase)
Fed batch or chemostat (continuous nutrition)
B-lactam group (four atom cyclic amide) is the _____________ of all B-lactam antibiotics. Give the names of some of the B-lactam antibiotics. [4]
Pharmacophore. Penicillins, carbapenems, cephalosporins, monobactams
What can cause a sensitive bacteria to become resistant to an antibiotic? [2]
What are some of the ways that this can happen?
Spontaneous mutation or acquisition of a gene (horizontal transfer)
[see picture]
What is the major cause of resistance to penicillins? What does it do?
What drug can help deal with this when used alongside penicillin?
Acquisition of beta-lactamase gene - it cleaves the beta-lactam ring.
Clavulanic acid
What are the three basic steps of using genetics to create a drug from a microorganism
- Find appropriate microorganism
- Transform gene -> enzyme expressed, metabolite synthesized
- Utilize whatever you have created as a therapy. Muahaha.
How is human insulin created nowadays?
What other advantage does this have over natural insulin?
In yeast or E Coli. Genes to create human insulin were inserted into these microbes - polypeptide chains A and B manufactured separately, and then disulfide bonded afterwards
Recombinant insulin can be modified (eg: fast/slow acting)
[NB: possibly interesting - disulfide bonds need oxidising conditions… in cell cytoplasm it is a reducing environment, due to glutathione (sp?), which is why most proteins with disulfide bonds are extracellular]
What is the effect of Hep B?
How was the hep B vaccine created?
Affects liver. Sickness w/vomiting, jaundice, tiredness, cirrhosis, liver cancer
Took gene for protein shell of virus, put it into baker’s yeast via a plasmid… the yeast will then express these proteins (antigens), which can be harvested and used to create the vaccine
Artemisinin & Malaria
What is synthetic/systems biology? Why was this difficult in the above case?
Trangenically creating not just one gene but a whole pathway (there were many steps in the sequence, and they not easy to locate)
Ethanol is produced by _____ (scientific name: ___________ __________). It takes _______ and converts it into what?
yeast, Saccharomyces cerevisiae, glucose
2 molecules of carbon dioxide, and 2 molecules of ethanol
Glucose is _______ during glycolysis (when NADH is produced). During ____________, pyruvate is converted to ___________ by the enzyme ________ _____________, which is then reduced to _______ by the enzyme _______ ____________.
oxidised, fermentation, acetaldehyde, pyruvate decarboxylase, ethanol, alcohol dehydrogenase
What enzymes are overexpressed in yeast?
Why might they produce ethanol (evolutionarily)?
Pyruvate decarboxylase, alcohol dehydrogenase
To kill other microbial life forms (and they have enzymes that convert ethanol and allow it to re-enter the TCA cycle, and eventually produce energy)
What foodstuffs can be converted into ethanol?
Why is this not actually environmentally friendly (at least when it comes to production of fuel)?
Sugar rich crops (sugar cane, sugar beet, potato, cassava, etc)
It is only a partially renewable resource. Sunlight might fix the energy into sugars, but ethanol produced is only 10%, and it needs energy input to distill it into a form that can be used for fuel.
