Students:
Bakratsas Georgios , Nikolaou Tasos
Department of Biological Applications and Technologies, University of Ioannina
Department of Biological Applications and Technologies, University of Ioannina
Experimental
course
Sampling
for the construction of the Winogradsky column took place on 20/10/2017 in the
Koronissia region on the Gulf of Amvrakikos. After collecting the necessary
amount of sludge (for 3 Winogradsky columns), it was enriched with the
following nutrients:
• 3 g CaCO3
• 3 g CaSO4
• 3/4 of
the newspaper page
• 3 eggs
• 12 g of
onion-garlic mixture.
It is noted
that a small amount of sludge was not enriched with nutrients to form the upper
layer of the Winogradsky columns.
Our team
constructed 3 columns, which were filled with 3/5 sludge, 1/5 water from the
lagoon and 1/5 air. From the three columns one was the control and was placed
at room temperature near a window (access to solar radiation ), the second
identical to the control was placed in a water bath at a temperature of 50-55 °
C while the third was enriched with 8 g of activated yeast in the sludge layer
and placed at room temperature near a window.
The second
and third columns will be compared to the control.
Experimental
hypotheses
1. The
column placed in the water bath is expected to have less microbial variation
due to the effect of temperature, which only allows the development of
heat-resistant micro-organisms.
2. Larger
microbial diversity is expected in the yeast column since, with the
introduction of yeast, the production of alcohol which is a nutrient of the
sulfur-reducing bacteria is accelerated. Therefore, the sulfur cycle is
enhanced by increasing the populations of micro-organisms affected by it.
Results
At the time
being, the experiment is not in a stage in which we can gather sufficient data
about the bacteria in order to conclude a specific result.
Over the
course of two months, we only observed a small bacterial growth in the control
Winogradsky column in the upper sludge layer. In particular, the developed
bacteria had a reddish color which lead us to the assumption that they belonged
to the purple non-sulfur bacteria. Apart from the bacteria, there was a
development of a white Fungi in the upper layer. Regarding the second and the
third column, there was no observable bacterial development.
As far
as the hypotheses are concerned, both of them were rejected since neither the
addition of yeast did accelerate the bacterial growth (more bacterial growth in
the control) nor the amount of time for the processing of the experiment was
enough for the development of heat-resistant micro-organisms (no comparison
with the control is available).
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| Picture 1 Winogradsky columns first day |
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| Picture 2 Purple bacteria and white Fungi in Control |
Did you observe fungi growth in columns 2 and 3? Any idea why they were favored against bacteria in the several columns? :)
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