Production of Penicillin
Group Number 3
Group Members:
 Nemdharry Devashi Devi (31624575)
 Priyadarshinee Boojhawon (31668482)
 Hu Shi (32082998)
Production of Penicillin
ABSTRACT
Penicillin is a group of antibiotics, a secondary metabolite from the fungus Penicillium and is
produced when growth of the fungus is inhibited by stress. Penicillin G is the most widely
used form of penicillin. It is produced in a batch culture. It has a bacteriostatic effect on
spore forming bacteria. The aims of this experiment were to test whether the penicillin
production occurred at higher rates during the idiophase and to determine the production
of biomass and penicillin by the fungus Penicillium chrysogenum. This is not an abstract of
your work but more like an intro.
INTRODUCTION
Penicillin G, C16H18N2O5S, was the first naturally occurring antibiotic discovered (Tom and
Lynne). Some microorganisms can form many types of metabolites, the primary and the
secondary metabolites. Primary metabolism is the metabolism of energy production for the
cell and for its own biosynthesis while secondary metabolism regards the production of
metabolites that are not used in energy production (Tom and Lynne) (Stanbury, 1998).
Microorganisms that produce secondary metabolites display two phases in a batch culture.
Those are the trophophase and the idiophase. Trophophase is the growth phase of the
culture and idiophase is when secondary metabolites are produced. A batch culture simply
means that a fixed amount of substrate is added at the beginning of the process (Tom and
Lynne). Penicillin G is a secondary metabolite and is produced mainly when growth has
stopped during the idiophase (Tom and Lynne).
MATERIALS & METHODS
The materials and methods are described in the Murdoch University BIO301 Industrial
Bioprocessing and Bioremediation Laboratory Manual 2013, Practical on Production of
Penicillin, pages 14-19.
Production of Penicillin
RESULTS
Data: A standard curve was plotted using the simple dilutions of standards supplied and
then these were spread onto sterile disks. The dilution table is as illustrated on table 1:good
Table 1: Dilution for table for standard curve:
Standards (U/30ul)
Sterile control
0.02
0.04
0.1
0.25
0.50
1
2
3
4
6
Diffusion Diameter (mm)
0
6
10
14
18
20
24
25
26
27
28
7
Penicilin concentration(u/30ul)
6
5
4
3
2
1
0
0
5
10
15
20
25
Diffusion diameter(mm)
Figure 1: Standard Curve of penicillin Inhibition Zone
30
Production of Penicillin
Problem 1:
Table 2: Biomass concentration at different sampling times and the rate of penicillin
production over time.
Sample time
(h)
Biomass Dry wt(g)
Biomass
Inhibition
Penicillin
concentration
zone(mm)
production
(g/L)
rate(U/L/h)
0
0.0651
15
0.651
24
0.4042
4.042
16
0.069
40
1.08
10.8
21
0.83
47
1.2632
12.632
22
0.952380952
63
2.092
20.92
23
0.208333333
70
1.5362
15.362
25
5.238095238
134
2.4111
24.111
22
-0.625
You show more digits than what can possibly within the accuracy of your measurments.
How was the very high rate at sample time 70 h obtained. Sample calculation would be
usefu.
Linear graph of Biomass and Penicillin Concentration against time
70
Trophophase
Biomass concentration(g/L)
60
Iodiophase
e
50
biomass concentration
40
penicillin concentration
30
y = 0.1821x + 2.8235
Linear (biomass
concentration)
20
10
0
0
50
100
150
Time(h)
Figure 2: Linear plot of Biomass and Penicillin Concentration against time. Why
trying to fit a linear equation to the biomass growth if in fact an exponential development is
expected? The penicillin concentration is too high or the units are incorrect. How do the
penicillin numbers in this plot relate to the ones in the table?
Production of Penicillin
Semi-log plot of biomass conc and penicillin conc against
time
Penicllin and biomass conc (g/L)
100
y = e0.526x
Biomass
conc (g/L)
10
Penicillin
conc (U/L)
1
0.1
0
24
43
48
Time (h)
53
72
163
Figure 3: Semi-log plot of Biomass and Penicillin concentration against time.
From figure 2, the Linear plot of Biomass and penicillin concentration versus time, the
separation between Trophophase and Idiophase can be seen clearly.
Introduce all figures first with text.
Problem 2:
According to Figure 2, the highest concentration of penicillin produced was at the point
where biomass concentration started to drop. This looks like over-interpretation of an
outlier point to me. When Biomass concentration was 20.92 g/L, there was a rise in
penicillin concentration. Thus, from figure 2, the slope of the curve for penicillin
concentration will give us the rate at which penicillin was produced. The slope was steepest
during the trophophase hence we can say that the penicillin production rate was highest in
the trophophase. You were supposed to conclude whether there is a trophophase from the
results.
The graph of penicillin versus time will be expected to be an increasing curve reaching a
peak value and then decrease after the peak value has been reached and then stays
constant. Why is that expected?
Production of Penicillin
The graph Penicillin versus time is shown below.
Penicilin production rate vs time
Penicilin production
rate(uint/L/h)
6
4
2
0
-2
0
50
100
150
Time(h)
From the above graph, the penicillin production rate dropped dramatically. Where?This is
because the secondary metabolite acted as an inhibitor for the cells at high concentration.
You can’t base conclusions on one single point
Problem 3:
Using the formula:
Specific growth rate = ln2 / td (doubling time)
From the semi log plot, the doubling time, td, is approximately= 8.6 hours
Therefore the specific growth rate = ln2/ 8.6 = 0.081 h-1
Whereas the specific growth rate for the linear plot is = 0.1821 h-1 which is a little bit higher
than in the value obtained from the semi log plot but lies within the same range.
Production of Penicillin
Problem 4:
Table 3: Penicillin production rate of each sampling interval.
Sample Time (h)
0
24
40
47
63
70
134
Penicillin production rate (Units/L/h)
0.027777778
0.833333333
0.952380952
0.208333333
5.238095238
-0.625
Penicilin production rate vs time
Penicilin production rate(uint/L/h)
6
5
4
3
2
1
0
-1
0
20
40
60
80
100
120
140
160
Time(h)
Figure 4: Graph of Penicillin Production Rate vs Time. The shape of this curve is almost
identical to that of the figure above. Extra marks if you can convince me that this chart has
taken into consideration the different biomass values
Conclusion: For the first 20 hours, penicillin production rate was zero. This is because at this
phase, primary metabolites were present speculative and these metabolites are essential
for the growth of the cells incorrect. When cells grow, they start producing secondary
metabolites which secondary metabolites, (what is the evidence?) until they reach a
maximum value at 5.2 unit/L/hr (Idiophase). Before the highest value was reached, the
penicillin production rate dropped to zero at around time, T, = 63 hours. This (what?) can be
due to the presence of primary metabolite which is competes for the active site of the
Production of Penicillin
enzyme. Very speculative. Which enzyme? As the primary metabolite start to decrease, cells
reach the stationary phase; penicillin production rate is highest as there is no similar
substrate analogue to compete for the active site of the enzyme. Then the production rate
decreases until it reaches a value under zero; -0.625 unit/L/hour at time t= 134. This must
be due to product inhibition (Stanbury, 1998) a negative rate is not explained by product
inhibition. What does a negative rate really state?
Problem 5:
Table 4: Specific Penicillin production rate of each sampling interval.
Time (Hr)
Specific Production Rate (units/g/L)
0
24
40
47
63
70
0
0.017180714
0.076677708
0.075394312
0.009958572
0.340977427
Specific production rate (units/g/L)
Specific production rate vs time
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
-0.05 0
20
40
60
80
100
Time (hr)
120
140
160
Figure 5: Graph of Specific Penicillin Production Rate vs Time. What is different her to figure
4?
According to the graph, the specific production rate is at its highest at 47 hours. After 47
hours, the graph shows a decrease. This may be due to the fact of product inhibition.
Production of Penicillin
Problem 6:
Penicillin G is being produced in response to the presence of gram-positive bacteria and is
produced as a secondary metabolite (Tom and Lynne).
No. The type of penicillin that is produced depends on the organism and medium
conditions.
Problem 7:
A sterile control was included in the experiment so as to ensure that during the inoculation
process, the culture was not contaminated.
No How can contamination be avoided by adding a sterile control?
References

Peter.F. Stanbury. Fermentation technology.1998

Ralf.C Ruwish. (2013). BIO 301 Industrial Bioprocessing and Bioremediation
Laboratory Manual. Murdoch University, Perth, WA.

Tom O’Hara and Lynne White. Penicillin Production incomplete reference
While a lot of work has been done and graphs have been plotted, the key purpose is not
achieved , which is to interprete from the data whether there are tropho phase and idio
phase. Instead of concluding from your results you take for granted that there must be two
phases .
The over-interpretation of a single outlier point point has resulted in some speculation
which is neither based on literature nor on own data.
The report did not really convince of a good understanding. How do you data would a
proper secondary metabolite look like like In future reports stick to what comes out and
admit if there are inconsistencies of data.
Less speculation, and a more critical approach is needed. 6/10
Production of Penicillin