MB Unit 19: Production of antibiotics

25 flashcards · Other · by Yaiza Anido

1. what was the first antibiotic produced by a microorganism and which m.o produced it

   The first antibiotic produced by microorganisms was Tyrothricin an dit was produced by Bacillus brevis

2. What is Tyrothricin and what is it used for?

   It is an antibiotic that is a mixture of gramicidin (20%) and tyrocidine (80%), and it could be used against gram + cocci and some gram – bacilli (like Neisseria spp).

3. Reason why it is nowadays forbiden to use antibiotics in animal feeding

   Years ago they were used in animal feeding, but it is forbidden nowadays because you trigger a lot of resistance mechanisms in their microbiota. Waters containing the faeces of those animals are used to water plants, they may get also this antibiotic resistance. Therefore, today they are only used for treating animal infections.

4. Name 3 antibiotics used in plant infections

   Blasticidine: for fungal infections in plants Mildiomycin: For treating milium (a fungi that affects plants) Cicloheximide: To inhibit translation of the eukaryotic ribosome (this can also be toxic to us)

5. what is the best producer for penicilin?

   Penicilium chrysogenum.

6. What was the problem with penicillium notatum and how did scientis see they could increase the yield?

   Soon after the discover of penicillin they saw Penicillium notatum’s yield was very low, and started looking for other Penicillium like Penicillium chryogenum. They also saw we could increase that yield even more by creating mutants.

7. In order to increase penicilin yield, how were the initial P.chrysogenum mutants obtained?

   Initial P.chrysogenum mutants were obtained by UV nitrogen mustard

8. How can penicillins be produced from recombinant gene expression?

   in this example, we see they have identified all the genes involved in the synthesis of penicillin and introduced them in a plasmid. Basically all they had to do was clone these clusters of genes into a plasmid and express the recombinant proteins of the genes in penicilin enzymes. It can also be produce by fungi protoplast fusion (diploid strains produce a better yield)

9. When producing penicillins from fungi protoplast fusion, how are some strains selected in order to obtain a better yield.

   First of all, diploid strains produce a better yield. Some strains are selected based on the adaptation to the oligo element composition of the substract

10. How do we obtain semisynthetic penicilins.

    It is cheaper to produce semisynthetic penicillin by getting the penilanic group then cutting the radical with acylases and getting the beta lactam ring. Then we add whatever we need to add to get amoxicillin, methicillin etc.

11. In the production of semisynthetic penicillins, what is the initial substrate for the ring?

    The initial substrate for the ring are the natural penicillins.

12. What can natural penicillins be used for?

    Natural penicillins are the initial substrate for the ring. Natural penicilllins can also later be used to purify the core penicillanic group and be chemically modified to obtain different penicillin derivatives.

13. Explain penicillin biosynthesis.

    The chemical pahtway starts with the transformation of lysine into alpha amino lipidic acid whcih is our substrate. Now our substrate (the alpha amino adipidic acid) 9s transformed iwth the incoorporation of 2 amino acids (cys and val) into the first penicillin molecule known as Isopenicillin N (this incorporation of the 2 amino acids is performed by the enzyme Ispenicylin N synthase (IPNS)

14. Mention the basic composition of the reactor for penicillin production

    A source of carbon: in this case lactose and small amoutns of glucose A source of Nitrogen and oligo elements: in this case corn steep liquor Small amounts of lysine We use lactose as source of C and steep corn liquor as N donor when cultivating Penicillium for antibiotic production. We do not use glucose as initial substrate because using large quantities at the beginning can affect the fermentation, so they usually add it when the fermentation has already started (at day 3). The content of P…

15. What can high glucose conc. cause in a penicillin production reactor? When can we add small amounts of glucose to the reactor?

    High glucose conc. can inhibit penicillin production Small glucose amounts can be added to the process on day 3 of the fermentation

16. What can an excess of phoshphorous and lysine cause in the proces of penicillin production?

    An excess in P and Lys can inhibit the process.

17. Explain the industrial production of penicillin process.

    The process starts with small amounts of spores which are lyophilized (freezed or dryed) The lyophilized spores are then cultured in solid agar for a few days until we start to have some prefermentation. Then we scale up; importat: every time we scale up we go to the next step by using 20% of the volume present in the previous one EXCEPT for the final one for which we add 10% and we add a lot of steep corn liquor and the other substrates We ferment that for 8 days at 30 degrees and a pH of 7 (a…

18. Interpret the following graph of the penicillin fermentation reactor kinetics for P.chrysogenum

    In this graph we can see that the initial componets are lactose and steep corn liqour (if we dont have this we can use amonium as the source of N) . We do NOT have penicillin at t=0, as we can see we first have biomass and then we have the penicillin. This indicates that penicillin is a secondary metabolite Only when we have low con. of lactose is when we can add small aounts of glucose.

19. What is a cephalosporin

    Any of a group of semi-synthetic broad-spectrum antibiotics resembling penicillin. The beta lactam ring is slightly different.

20. Explain the Cephalosporin biosynthesis by cephalosporium acremonium

    The industry uses cephalosporium anemonium for the synthesis of cephalosporins. The initial steps are the same except that at a certain point, the penicilin N is transformed into deacetyl cephalosproin C thanks to the enzyme Expandase.

21. What is the importance of the enzyme expandase in the biosynthesis of cephalosporium acremonium?

    Its a key step to pass from the betalactam ring into the cephalosporin ring which is performed by the enzyme expandase. (Then the hydrolases and transferases give us different cephalosporins)

22. What is the importance of the hydrolases and transferases in respect to expandase in the biosyntheis of cephalosporin?

    After the betalactam ring has been transformed into a cephalosporin ring by the expandase, the hydrolases and transferases are the ones that will give us the different isomeric forms of cephalosporin.

23. Interpret the following graph about cephalosporin fermentation reactor kinetics for cephalosporium acremonium

    Low lysine concentration stimulates production. High amounts are detrimental.

24. How did the specificity of cephalosporins change over its 5 generations

    The first generations were more specific for gram + and had very little activity for gram -

25. Name 2 5th generation cephalosporins

    Ceftobiprole: has a hgih activity against methicillin-resistant staphylococcus aureus, penicillin resistant streptococcus pneumonie, pseudomonas, and enterococci Ceftaroline: which is active against daptomycin-resistant, methicillin-resistant and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) and penicillin-resistant Gram-positive bacteria including Streptococcus pneumoniae. It retains the activity of later-generation cephalosporins having broad-spectrum activity against Gram-negati…