Penicillin Production

Industrial Production of Penicillin using
Penicillium chrysogenum
Industrial Biotechnology
25th
October 2013
Nazeer Huda
Seetul Yajeshwar
Cécile Christabelle

Overview
● Introduction
● What is penicillin?
● History
● General structure of penicillins
● Penicillin derivatives
● How does penicillin work?
● Spectrum of activity
● Fermentors
● Important aspects of fermentors
● Specific conditions for
production
● Media consideration &
formulation
● Primary & secondary
metabolism
● Production method
● Stages of production
● Production of penicillin
● Classification of penicillins
● Increase in yield
● References

Introduction
We have all, at one point or the other, heard about penicillin. From its
accidental discovery and massive use in World War II to the Nobel
Prize for Medicine in 1945 by its rightful owners, penicillin has made its
proof as the “Miracle Drug” that revolutionized the course of the
medical industry.
Without further ado, let us take a look at an important aspect that made
penicillin accessible at large; its industrial production.

What is Penicillin?
● First true naturally-occurring antibiotic ever discovered: a great
medical breakthrough.
● Group of antibiotics produced by the Penicillium fungi.
It is a group of closely related compounds, not a single compound.
Examples: Amoxicillin, ampicillin, phenoxymethylpenicillin.
● Around 50 drugs that are penicillins.

History: Discovery & Production
● 1928: Scottish biologist, Alexander Fleming
discovered that the Staphylococcus culture he
had mistakenly left growing in open was
contaminated with a mould which had
destroyed the bacteria.
● After isolating a sample and testing it, he
found that it belonged to the Penicillium
family.
Later the mould was classified as Penicillium
notanum.
● At first, it was difficult to convince people
about its potential uses.

History: Discovery & Production
● But later (1939), using Fleming’s work, two medical
researchers, Howard Florey and Ernst Chain
managed to purify penicillin in a powdered form.
● 1941: They successfully treated a human.
● 1943: They produced penicillin on a large scale.
This helped immensely to treat casualties during the
WWII that had bacterial infections due to their
wounds.

General Structure of Penicillins

General Structure of Penicillins
● Have β-Lactam functional group, thus belong to the β-Lactam
antibiotic group.
● They all have a basic ring-like structure (a β-Lactam) derived from
two amino acids (valine and cysteine) via a tripeptide intermediate.
The third amino acid of this tripeptide is replaced by an acyl group
(R).
The nature of this acyl group produces specific properties on
different types of penicillin.

Penicillin Derivatives
● Derivatives produced to deal with the problem of bacterial
resistance to penicillin.
● All penicillin or penicillin derivative have a
constant core region which is the 6-APA.
● The only region that is different from different types of penicillin
derivative is its R group.

How Does Penicillin Work?
● Inhibits the synthesis of peptidoglycan in cell walls.
○ β-Lactam of penicillin binds to the enzyme - transpeptidase,
that is used in the formation of peptidoglycan cross linking.
○ The enzyme is inhibited, thus inability to form cross linking.
○ Cell wall is weakened causing osmotic imbalance in the cell.
This leads to cell death.
● As human cells do not have cell walls, penicillin does not affect
them.

Spectrum of Activity
● Effective against actively growing Gram positive bacteria - which
have thick peptidoglycan.
● Some penicillins like amoxicillin are also effective against Gram
negative bacteria, except Pseudomonas aeruginosa.

Fermentors
● Purpose of fermentor:
○ provide contained, controlled and homogeneous environment
in which the fermentation can proceed in a manner that is both
safe and practical and which optimises the particular objectives
of the fermentation.
● Other primary factors include cost, reliability and safety.
● For reactor being designed for specific purpose, there are a number
of important parameters that will greatly affect performance:

1. Reactor Size: optimum rates of production?
2. Reactor Configuration: mechanical agitation or will a bubble
column.
3. Mode of operation: Will it be batch fed or continuously fed?
4. Conditions inside the reactor: how will conditions (pH,
temperature,…) be controlled?
Economic requirements:
● Easy to operate aseptically.
● Reasonably flexible regarding process requirements.
● Low power consumption.
● Stable under fluctuating conditions.
● Cheap, robust, simple and well understood for scale-up.
Fermentors

Some Important Aspects
● Mass Transfer: good transfer of oxygen across the liquid
interface-the Sparger delivers this oxygen efficiently.
● Heat Transfer: metabolism as a process tends to give off heat-
achieved through cooling jacket whereby cool water is passed
through.
● Bulk Flow and Mixing: impellers, bubble columns or loop
reactors.
● Batch, Fed-Batch and Continuous Culture: how nutrients
and substrate will be delivered to a culture in a reactor.
● Steam: Used to keep the reactor running aseptically.
(temperature/pressure of 121°C/15 psi for 15-30min).

● Batch: fixed amount of substrate is added at the beginning whereby
the volume of nutrients remains the same throughout the process.
● Fed Batch: substrate is added in small increments at various times
in the fermentation and consequently volume increases.
● Continuous: substrate is constantly added to the reactor while an
equal amount of fermented medium is removed. Volume again
remain the same but constantly renewed with fresh ones.
Batch, Fed-Batch and Continuous Culture

Specific Conditions for Penicillin Production
● Most penicillins form filamentous broths. This means they can be
difficult to mix due to their high viscosity. Also the increasing
viscosity of the broth can hinder oxygen transfer.

A solution for the viscosity and the
filamentous growth of penicillium
species could be bubble columns (air lift
reactors) which would distribute the
oxygen equally and also to agitate the
medium.

● •Penicillin is an aerobic organism; oxygen supply is critical: reactor
must have an efficient oxygen supply system.
● •The optimum pH for penicillin growth is 6.5: maintain pH
efficiently (pH controller and acid-base reservoir).
● •Strain Stability problems (mutations): careful strain maintenance is
required.
● •Biomass doubling is about 6h: provisions must be made.

Media Consideration
● The aim of the media is to:
○ provide all the elements required for the synthesis of cell
materials and the formation of the desired product.
○ provide favourable environment for the culture in question.
○ be cost effective.

Media Formulation
● pH 6.5
● Temperature 20-24 °C
● Oxygen
● Nitrogen: corn steep liquor 8.5 %
● Glucose 1%
● 80% ethanol
● phenylacetic acid
● Probenecid
● Lactose 1%
● Calcium Carbonate 1%
● Sodium hydrogen phosphate 0.4%
● Antifoaming agent: vegetable oil

● Microorganisms require C, H, O, S and N for cell growth and cell
maintenance.
● Also require small amounts of trace elements such as Cu, Mn and
Co (frequently depend on the water source) or growth factors such
as vitamins or amino acids.
● Certain organisms such as Penicillium chrysogenum that produce
antibiotics, enzymes or other secondary metabolites frequently
require precursors like purine/pyrimidine bases or organic acids to
produce metabolites.
Media Formulation

Primary and Secondary Metabolism
● Primary metabolism is the metabolism of energy production for the
cell and for its own biosynthesis. In aerobic organisms (such as
Penicillium chrysogenum) it involves the conversion of sugars such
as glucose to pyruvic acid and the production of energy.
● Secondary metabolism regards the production of metabolites that
are not used in energy production for example penicillin from
Penicillium chrysogenum. The metabolite is being utilized as a
defence mechanism against other microorganisms in the
environment. Penicillium chrysogenum can kill off the competition
to allow itself to propagate efficiently.

Production Method
● Secondary metabolites are only produced in times of stress when
resources are low and the organism must produce these compounds
to kill off its competitors to allow it to survive.
● It is these conditions that we
wish to duplicate in order to
achieve the maximum
amount of product from our
fermentation.

Stages of Production
1. Primary metabolism will be emphasised. Media for this stage will
be focussed on achieving maximum growth and biomass
production.
2. Once the desired biomass has been achieved, starve (Limiting the
amount of C and N available to the culture) the culture and induce
the kind of stress conditions that trigger the production of the
antibiotic.
★ Use the fed-batch method to feed the culture. As stated above, this
allows us to add the substrate to the reactor in small increments
and to even change the substrate if we so desire.

Production of Penicillin
● Penicillin was the first important commercial product produced by
an aerobic, submerged fermentation.
● First antibiotic to have been manufactured in bulk.
● At the end of the WWII, penicillin was first made using the fungus
Penicillium notatum, which produced a yield of 1 mg/dm3
● Today, using a different species known as Penicillium
chrysogenum, and better extraction procedures, the yield is 50
mg/dm3

The Industrial Production of Penicillin
This can be broadly classified into two processes namely:
1. Upstream Processing
- referring to processes before input to the fermenter and
encompases any technology that leads to the synthesis of a product.
It includes the exploration, development and production.
2. Downstream Processing
- referring to processes done to purify the output of the fermenter
until it reaches to the desired product, such as extraction and
purification of a product from fermentation.

Process Flow Diagram: Penicillin

★ Medium for penicillin
1. The Penicillium chrysogenum usually contain its carbon source
which is found in corn steep liquor and glucose.
2. A medium of corn steep liquor and glucose are added to the
fermenter. Medium also consists of salts such as MgSO4
, K3
PO4
and
sodium nitrates. They provide the essential ions required for the
fungus metabolic activity.

★ Heat sterilization
3. Medium is sterilized at high heat and high pressure, usually through a
holding tube or sterilized together with the fermenter.
4. The pressurized steam is used and the medium is heated to 121°C at 30
psi or twice the atm. pressure
Note: High temp. short time
conditions are used to minimise
degradation of certain components
of the media.
Sterilisation machine

★ Fermentation
5. It is done in a fed-batch mode as glucose must not be added in high
amounts at the beginning of growth (which will result in low yield of
penicillin production as excessive glucose inhibit penicillin production).
6. The fermentation conditions for the Penicillium mold, usually
requires temperatures at 20-24°C while pH conditions are kept at 6.5
7. The pressure in the bioreactor is much higher than the atmospheric
pressure (1.02atm). This is to prevent contamination from occurring as it
prevents external contaminants from entering.

★ Fermentation
8. It is necessary to mix the culture evenly throughout the culture
medium. Fungal cells are able to handle rotation speed of around 200
rpm.
Fermentors

★ Seed Culture
9. The seed culture is developed first in the lab by the addition of
Penicillium chrysogenum spores into a liquid medium. When it has
grown to the acceptable amount, it is inoculated into the fermenter.
10. The medium is constantly aerated and agitated. Carbon and
nitrogen are added sparingly alongside precursor molecules for
penicillin fed-batch style. Typical parameters such as pH, temperature,
stirrer speed and dissolved oxygen concentration, are observed.

★ Seed Culture
11. After about 40 hours, penicillin begins to be secreted by the fungus.
12. After about 7 days, growth is completed, the pH rises to 8.0 or above
and penicillin production ceases.
The Penicillium fungus

★ Removal of biomass
13. Filtration is carried out as bioseparation is required to remove the
biomass from the culture (removing the fungus and other impurities
away from the medium, which contains the penicillin).
14. A Rotary vacuum filter is commonly employed for filtration as it is
able to run in continuous mode in any large scale operations.
15. After filtration, phosphoric acid,
a non-oxidising agent, is introduced,
to decrease pH from 8.0 to 6.5 so as
to prevent loss of activity of penicillin.
Rotary vacuum filter

★ Addition of solvent
16. Organic solvents such as amyl acetate /
butyl acetate are added to dissolve the
penicillin present in the filtrate.
17. At this point, penicillin is present in the
solution and any other solids will be considered
as waste (can be used as fertilizers and animal
feed).

★ Centrifugal Extraction
18. Centrifugation is done to separate the solid
waste from the liquid component which contains
the penicillin.
19. Usually a disk centrifuge is used at this point.
20. The supernatant will then be transferred
further in the downstream process to continue
with extraction.
Disk centrifuge - One of the most
common type of centrifuge for large
scale production

21. A series of extraction processes are carried upon the dissolved
penicillin, to obtain a better purity of the penicillin product.
22. The acetate solution is first mixed with a phosphate buffer, followed
by a chloroform solution, and mixed again with a phosphate buffer and
finally in an ether solution.
23. Penicillin is present in high concentration in the ether solution and
it will be mixed with a solution of sodium bicarbonate to obtain the
penicillin-sodium salt, which allow penicillin to be stored in a stable
powder form at rtp.
★ Extraction

★ Extraction
24. The penicillin-sodium salt is obtained from the liquid material by
basket centrifugation, in which solids are easily removed.
Batch extraction unit Basket Centrifuge: Extremely useful in the
removal of solids in this case Penicillin salt

★ Fluid bed drying
25. Drying is necessary to remove any
remaining moisture present in the powdered
penicillin salt.
26. In fluid bed drying, hot gas is pumped from
the base of the chamber containing the
powdered salt inside a vacuum chamber.
27. Moisture is removed this way, and this
result in a much drier form of penicillin.
Powdered penicillin being
blown by hot air
Fluid bed drying
tube

★ Storage
28. Penicillin is stored in containers and kept in a dried environment.
The White Penicillin-Sodium salt
29. The resulting penicillin (called Penicillin G) can be chemically and
enzymatically modified to make a variety of penicillins with slightly
different properties.
30. These can be semi-synthetic penicillins, such as; Penicillin V,
Penicillin O, ampicillin and amoxycillin.

Classification of Penicillins
Four known classes:
1. Natural Penicillins
2. Penicillinase-Resistant Penicillins
3. Aminopenicillins
4. Extended Spectrum Penicillins
Categorized based on their ability to kill types of bacteria and how
effective are they in doing so.

1. Natural Penicillins:
● The natural penicillins are based on the original penicillin-G
structure.
● They are effective against both gram-positive strains and gram
negative bacteria.
● Examples of Natural Penicillins are Penicillin G, Procaine,
Penicillin O, Penicillin V and Benzathine.

2. Penicillinase-Resistant Penicillins:
● The Penicillinase-resistant penicillins have a narrower spectrum of
activity in contrast to the natural penicillins.
● Their antimicrobial efficacy is targeted on penicillinase-producing
strains of gram-positive cocci, such as Staphylococcal species and
these drugs are also known as ‘anti-staphylococcal penicillins’.
● Examples of Penicillinase-Resistant Penicillins are Dicloxacillin,
Methicillin, Nafcillin, Oxacillin and Cloxacillin.

3. Aminopenicillins:
● Active against gram-negative bacteria (such as E. coli).
Aminopenicillins are acid-resistant-can be administered orally.
● Orally administered amoxicillin and ampicillin are used primarily
to treat mild infections such as otitis media, sinusitis, bronchitis,
urinary tract infections and bacterial diarrhoea.
● Examples of Aminopenicillins are Amoxicillin, Ampicillin and
Bacampicillin.

4. Extended Spectrum Penicillins:
These agents have similar spectrums of activity as compared to the
aminopenicillins but it has an additional activity, which is against
several gram negative organisms in the family Enterobacteriaceae and
some strains of Pseudomonas aeruginosa.

Increasing Yield
1. Adding corn syrup
2. Selection of strain
3. Mutation and Selection
4. Sexual reproduction

1. Corn syrup
Allow maximal growth of the culture at the expense of product
(antibiotic) formation. This is because growth and antibiotic
production are inversely proportional.
More secondary metabolites during stress phase.
Increasing Yield

2. Selection of strain
● Selection of the best strain
depends on the production rate
of the secondary metabolite
(penicillin).
● Penicillium notatum (1 mg/dm3
)
and Penicillium chrysogenum
(50 mg/dm3
).
● Strains are grown on cultures in
laboratories and those with best
yield is determined.
Increasing Yield

3. Mutation and Selection
This is based on trial and chance.
● Several strains of Penicillium are cultured.
● Ethyl methanesulphonate (EMS), near-ultraviolet light
in the presence of 8-methoxypsoralen (8MOP) are used
as mutagens.
● Combination of the mutagens leads to a more positive result.
● Strains are exposed to the mutagens at different intensities and
proportions.
● Each time the best strains are selected and are further exposed.
● Statistical tests are done to determine the strains with highest
yields.
● Dry conidia is stored in silica gel at 4°C at each stage.
Increasing Yield

4. Sexual Reproduction
● It was assumed that the penicillin-producing mould fungus
Penicillium chrysogenum only reproduced asexually through
spores. Fungus also has a sexual cycle (Jan.8 2013)
● The progenies possess a combination of genes from both mating
partners and thus have new properties, both at the molecular level,
as well as in their phenotypes.
● Specific environmental conditions; in the dark under oxygen
deprivation conditions in a nutrient medium supplemented with
the vitamin biotin.
Increasing Yield

How is Penicillin-G enzymatically
modified?
● Using PGA (Penicillin G acylase) which is a hydrolytic enzyme.
● It acts on the side chains of penicillin G to produce β-lactam antibiotic.
This antibiotic has by-products which has the potential building blocks
of semi-synthetic antibiotics, such as ampicillin and amoxicillin.
● The high demand for PGA is being met through a submerged
fermentation process that uses genetically manipulated E.coli and
Bacillus megaterium microorganisms.
● Advancements in biotechnology such as screening of microorganisms,
site-specific mutagenesis, immobilization techniques, and modifications
to the fermentation process could enhance the production of PGA.

References
http://penicillin.wikispaces.com/Home (15/09/2013)
http://penicillin.wikispaces.com/General+bioprocess+flow (15/09/2013)
http://penicillin.wikispaces.com/Various+types+of+Penicillin (15/09/2013)
http://microbiologyprocesses.blogspot.com/2011/12/penicillin-production.html
(20/09/2013)
http://inventors.about.com/od/pstartinventions/a/Penicillin.htm
(20/09/2013)
http://www.medicinenet.com/penicillins-oral/article.htm (30/09/2013)
http://www.eolss.net/Sample-Chapters/C17/E6-58-05-04.pdf (3/10/2013)
http://mic.sgmjournals.org/content/113/2/209.full.pdf+html (11/10/13)
http://www.sciencedaily.com/releases/2013/01/130108084138.htm (11/10/13)
http://archive.bio.ed.ac.uk/jdeacon/microbes/penicill.htm (11/10/13)
http://www.sciencedirect.com/science/article/pii/S0141022907003560
(07/11/13)

Thank you for your attention!
Any questions?
When life gives you molds, makepenicillin!

Penicillin Production

More Related Content

Penicillin Production