introduction to biotechnology-- lab report for Professor Naiyyum Choudhury class

1. Lab Report 2011
1 BTE 101
BTE 101
Introduction to Biotechnology and Genetic Engineering
Professor Naiyyum Choudhury
Lab. Reports:
Sl.
No.
Experiment Name Page no.
01 Yogurt Production 2
02 Bacterial Culture by Streaking 3
03 Production of Maltose by Starch Hydrlysis 4
Done by: Samiya Yesmin
I.D. 11304043
B.B.S.

2. Lab Report 2011
2 BTE 101
Experiment 01-
1. Name of Experiment: Yogurt production
2. Purpose: Fermentation of milk to produce Yogurt.
3. Principle: Fermentation of milk produces yogurt, a food delicacy enjoyed over centuries.
Fermenting milk results in milk lactose sugar produces lactic acid, glucose, galactose and flavor
components, which forms a good thick conjugated texture. Yogurt is now industrially produced
by the following major steps:
a. Media preparation: Milk is heated at 85o
C for approximately 2 minutes to kill all the micro-
organisms and denature the enzymes. Then cooled.
b. Inoculum preparation: it is the preparation of yeast or Lactobacillus bulgaricus, micro-
organisms used for fermentation:
c. Fermentation: it is the process in which the media and culture are added together ten left
to incubate at 37o
C for 24 hrs, although this time varies depending on the texture of yogurt
needed to be produced.
4. Materials used:
a. 50ml of milk media.
b. Heat source.
c. Starter culture of yeast and Lactobacillus
bulgaricus (1ml of each used)
d. Incubator
e. 100 ml beaker.
f. Aluminum Foil paper.
5. Results/ Observation: as milk lactose gets conjugated
it forms a thicker less volume yogurt as shown 
6. Discussion: as we can see our volume of yogurt
produced is very less due to the fact that diluted milk
was used for the process. To produce more yogurt,

3. Lab Report 2011
3 BTE 101
concentrated milk should be used as that will have a higher content of milk lactose sugar.
Experiment 02-
1. Name of Experiment: Aseptic culture technique by streak plate method of isolation.
2. Purpose: To get single strain colonies of microorganisms.
3. Principle: To study or to work with any
microorganisms, it is important to use a single strain
colony as microorganisms are easily contaminated
which would ruin any work it is being used for. Thus
by streaking method we can produce single strain
colonies.
4. Materials used:
i. Petri Dishes
ii. Agar culture plate
iii. Inoculating loop
iv. Bunsen Burner
v. Stock Bacteris
vi. Incubator 37o
C
5. Results/ Observation:
as it was my first time streaking, I could
not do it perfectly, thus no single strain colonies
were formed. As u can see in the pictures. The
bacterial growth formed irregular shape, with
undulated edges that grew into the medium and
had a flat elevation. Due to proper sterilized
conditions there were no fungal growth.
6. Discussion: with more practice on how
to streak, I will be able to get proper single strain colonies. As this process needs practice as
well as patience.

4. Lab Report 2011
4 BTE 101
Experiment 03-
1. Name of Experiment: Enzymatic Assay of α- Amylase
2. Purpose: To find the mass of Maltose released by α- Amylase reaction.
3. Principle: By doing this experiment we will be able
to find the mass of Maltose produced by the
hydrolysis of 1ml starch solution using α- Amylase
solution of 1ml. Our experiment uses the standard
curve of maltose to find the amount of reducing
sugar in the unknown sample. The standard curve is
produced by creating different concentrations of
maltose and finding their optical densities. As shown
in the figure  we get different color densities for
different concentrations of maltose. The color
density increases as the concentration of maltose produced in the solution increases. TT9
is the control here.
4. Materials used:
i. 20 mM sodium Phosphate Buffer sol. With 6.7mM NaCl solution to have a pH of
6.9
ii. 1.0 % (w/v) Starch solution.
iii. Micro-pipette.
iv. Colour Reagent Solution.
v. 0.2% (w/v) Maltose Solution
vi. α- Amylase Solution

5. Lab Report 2011
5 BTE 101
vii. Spectrophotometer to measure Optical Density 
viii. 96 mM 3,5-Dinitrosalicylic Acid Solution
5. Results/ Observation:
The results for the standard curve and the experimental test sample, as shown below are
plotted in a graph.
TT 4 5 6 7 8 9
Conc. Of
Maltose
0.2 0.4 0.6 0.8 1.0 0
Optical
Density
0.04 0.105 0.135 0.153 0.195 0
And from their intersection we find that the concentration of maltose present in the test
sample which gives an OD of 0.3375 is 1.67mM
Now using the formula of concentration, C=m/Mr, we can find the mass of Maltose that
has been produced.
TT 1 2 3
Optical
Density
0.352 0.323 0
Average OD 0.3375
C=m/Mr
m=C*Mr
m=1.67*360.3
m= 601.701 mg

6. Lab Report 2011
6 BTE 101
6. Discussion: using this simple procedure we can easily find the unknown amount of maltose
being produced by starch enzymatic hydrolysis. As the test values are very small, we must be
very careful while doing this experiment as a slight error will show drastic difference in result.