Report: Optimum pH Effects on Mung Bean Germination and Bacteria

This report details a student's investigation into the effects of pH on mung bean germination and bacterial growth. The experiment involved exposing mung beans to various pH levels and observing their biomass changes over time. Additionally, the study explored the impact of washing liquid and mouthwash on bacterial growth, assessing the zone of inhibition. The report includes the methodology, data analysis, results, and a discussion of the findings, including the challenges faced, such as contamination and the limitations of the experiment. The results suggest that mung bean biomass increased with higher pH levels and the washing liquid/mouthwash inhibited bacterial growth. Safety precautions, limitations, and potential areas for future research are also discussed.

Running head: OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL
GROWTH
OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Name of the Student:
Name of the University:
Author Note:

1OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Table of Contents
Introduction................................................................................................................................3
MATERIALS AND METHODS...............................................................................................3
Experiment 1: Testing effects of pH on Mung beans............................................................3
a. Materials for the experiment:......................................................................................3
b. Methods:......................................................................................................................4
Experiment 2: Bacterial growth experiment..........................................................................4
a. Materials for the experiment:......................................................................................4
b. Methods:......................................................................................................................5
Data............................................................................................................................................6
Experiment 1: Testing effects of pH on Mung beans............................................................6
Experiment 2: Bacterial growth assessment..........................................................................7
Interpretation of the Data...........................................................................................................8
Experiment 1: Effects of pH on Mung beans:........................................................................8
1st batch-.............................................................................................................................8
2nd batch-............................................................................................................................9
Experiment 2: Bacterial growth experiment..........................................................................9
Results and Hypothesis..............................................................................................................9
Results from the mung bean experiment................................................................................9
Results from the bacterial growth experiment.....................................................................10
Safety Measurements...............................................................................................................10

2OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Limitations...............................................................................................................................11
Conclusion................................................................................................................................11
References................................................................................................................................11

3OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Introduction
Seed germination is one of the principal experiment to understand plant growth and
nutrient utilization in plants. Mung beans (Vigna radiata) are annual plants which can grow
up to 1 meter in length. Shorter germination time of typically 24 to 36 hours (El-Adawy et al.,
2003) has potentiated the use of this plant to study early stages sprouting and maturation of
the plant. Germination procedures are monitored with subsequent exposure to pH levels to
evaluate optimum pH (Mandal, Barman & Biswas, 1972) for mung bean growth.
Another experiment to observe bacterial growth on a nutrient agar media amplifying
the effects of washing liquid and mouth wash is also studied. Bacteria are prokaryotic
organisms having shorter generation time of 20 minutes (Golding et al., 2005). Effects of
washing liquid and mouth wash on bacterial growth reflecting zone of inhibition (Ericsson,
Tunevall & Wickman, 1960) in nutrient medium.
MATERIALS AND METHODS
Experiment 1: Testing effects of pH on Mung beans
a. Materials for the experiment:
i. Mung beans (Vigna radiata),
ii. Petri dishes,
iii. pH solutions (2,4,6,7,8,9,10,11),
iv. Beakers,
v. Conical flasks,
vi. Weighing machine,
vii. Weighing scale,

4OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
viii. Forceps,
ix. Cotton,
x. Filter paper,
xi. Tray,
xii. Marker pen.
b. Methods:
i. 10 mung beans were added in each of the respective pH solutions
(2,4,6,7,8,9,10,11) prepared in the beakers. mung beans were placed on two sheets
of filter paper with a cotton kept over the filter paper, to make the beans stay in
one place.
ii. 8 sterilized petri dishes were taken and two circular filter paper were situated
inside the bottom of the petri dish. The petri dishes were labelled by marken pen
with respective pH.
iii. Mung beans were transferred from the beaker to the cotton attached filter papers
placed in the petri dishes.
iv. This particular step was repeated eight times to transfer mung beans into their
respective petri dishes with appropriate pH, labelled by marker.
v. pH solutions were added into the petri dish gradually to submerge the mung beans
without stirring.
vi. Steady volume of pH solutions were maintained.
vii. This whole experiment was repeated once more to overcome the sample loss of
the first batch.

5OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Experiment 2: Bacterial growth experiment
a. Materials for the experiment:
i. Mouth wash,
ii. Washing liquid,
iii. Bacterial strain (micrococcus lutues),
iv. Bacterial strain (Bacillus subtilis),
v. Circular filter paper,
vi. Bunsen barner,
vii. Glass spreader,
viii. Nutrient agar,
ix. Water,
x. Foil,
xi. Laboratory coat,
xii. Gloves,
xiii. Black marker pen.
b. Methods:
i. Solutions of washing liquid and mouth wash of 4 different concentrations (100%,
75%, 50% and 25%) were made in 4 separate beakers.
ii. Four filter papers for different concentrations of washing liquid and mouth wash
solutions were soaked in the beakers respectively.
iii. 4 sterilized petri dishes consisting pre-made nutrient agar were labelled with a
marker pen according to control and initials of the bacterial strain and experiment
date.
iv. Bunsen burner was turned on and set in blue flame.

6OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
v. Proper inoculum was taken from the liquid bacterial source by removing the foil
wrap on the conical flask and burning the opening of the flask to avoid
contamination.
vi. After acquiring the bacterial samples, opening of conical flasks were reintroduced
into the blue flame and wrapped immediately with foil to prevent contamination
of the stock solution.
vii. 5 drops were added in each petri dish.
viii. Spreading was done evenly with a lawn spreader by applying appropriate
pressure. Spreader was dipped into alcohol and burnt every time followed by
cooling when spreading in each petri dish to avoid bacterial contamination and
heat effected killing of bacterial strains.
ix. Four subsequent concentration of filter paper dipped in washing liquid and mouth
wash was added to each petri dish as labelled except for two control petri plates.
Data
Experiment 1: Testing effects of pH on Mung beans
Growth of mung beans on exposure to specific pH-
1st batch-
pH Initial Biomass (grams)
pH2 0.93
pH4 0.86
pH7 0.84
pH9 0.92
pH11 0.90

7OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
pH Biomass after four weeks (grams)
pH2 1.08
pH4 NA (Contamination)
pH7 0.86
pH9 1.37
pH11 1.58
2nd batch-
pH Initial Biomass (grams)
pH2 0.85
pH4 0.90
pH7 0.90
pH9 0.84
pH11 0.89
pH Biomass after three weeks (grams)
pH2 0.96
pH4 1.47
pH7 0.83
pH9 1.45
pH11 1.88

8OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Experiment 2: Bacterial growth assessment
Different concentrations of washing liquid and mouth wash was prepared.
Concentration (%) Solution (ml) Water (ml)
100 2 0
75 1.5 0.5
50 1 1
25 0.5 1.5
Interpretation of the Data
Experiment 1: Effects of pH on Mung beans:
1st batch-
The data generated from the mung bean experiment to assess the amount of biomass are
shown in a graphical representation.

9OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
pH2 pH4 pH7 pH9 pH11
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Growth of mung beans (1st batch)
initial growth Column1
2nd batch-
pH2 pH4 pH7 pH9 pH11
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Growth of mung beans (2nd batch)
Initial Biomass Biomass after three weeks (g)
Experiment 2: Bacterial growth experiment
For bacterial growth practical, measurements of zone of inhibitions for washing liquid/mouth
wash treatment is still to be carried out.

10OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Results and Hypothesis
Results from the mung bean experiment
In case of the mung bean practical, contamination in pH solution resulted in spoilage
of a particular data set of pH4 of the first batch. Although, a full set of data was obtained by
repeating the experiment for the second time obtaining a second batch of results, and
carefully observed to prevent the chances of contamination of pH solution. Initial challenge
faced with fixation of the mung beans on the filter paper surface, while exposing them in the
solutions of pH prepared in the beaker was corrected by using cotton to prevent them from
floating off. Experimental data elucidated that proportional increase in mung bean biomass
was observed with increased level of pH. Consistency of data from the repeat experiment
confirmed the inference further, including the colour change of the mung beans exposed to
certain pH.
Study by Das and Singh (2014) have demonstrated that Vigna radiata achieves
optimum growth at pH level of 8.11 to 8.34, when combined with organic manure and plant
growth promoting rhizobacteria. Further studies focusing in this pH range is an absolute
necessity to assess the growth of the plant in absence of plant growth promoting
rhizobacteria.
Results from the bacterial growth experiment
For the bacterial growth experiment, unavailability of washing liquid was
manipulated using mouth wash to observe the inhibitory effect of these compounds. Samples
of Micrococcus luteus and Bacillus subtilis is still to be observed under these conditions by
measuring zone of inhibition for each of these compounds. A provision for comparative
analysis was accessible by adapting to the conditions necessary for the experiment.

11OPTIMUM pH FOR MUNG BEAN GERMINATION AND BACTERIAL GROWTH
Recent study, involving vancomycin (antibiotic) on methicillin-resistant
Staphylococcus aureus has found that a minimum inhibitory concentration of 1.0 mg/ litre is
effective for inhibition of growth of the bacteria (Dilworth et al. 2014).
Safety Measurements
Laboratory coats (Harley, 2014) and disposable gloves (Sewell, 2013) were used to
prevent any spillage from the bacterial source and unwanted contamination. Safety glasses
(Pommeville, 2010) were also used to prevent any harm to the eye. In case broken pieces of
glass were to be found, it was collected with a dustpan and discarded in the dust bin.
Limitations
Effects of pH on mung bean growth could have been analyzed further by repeating the
experiments with more pH concentrations. In addition, repeating the experiments with the
given concentrations of pH could have generated more data for greater evaluation of the plant
growth, which was not possible due to lack of time.
Conclusion
Initially it was determined that the mung bean experiment would be conducted. But
not having mung beans in laboratory lead to commencement of bacterial growth experiment
and was continued even after mung bean experiment was initiated due to slower growth of
beans in laboratory conditions. Additional challenge faced during bacterial growth
experiment when washing liquid was insufficient to progress this experiment. Added
comparison was explored with initial data generated by washing liquid with application of
mouth wash provided by Laboratory technician. This proposed an analytical possibility of
both these compounds reflecting effective inhibition of bacterial growth.