Winogradsky Column Materials:
All groups included 40g Rio San Pedro sediment, 100g sand
and sea water.
5A group’s column: 0,31g tryptone;
0,62g powdered milk; 0,1g CaSO4.
6A group’s column: 0,74g agar, 0,74g
CaCO3.
7A group’s column: 0,1g CaSO4,
0,3g paper (cellulose).
Procedure:
1º-. We took off the solids residues from the sediment. Then, we mixed 20g of Rio
San Pedro sediment with sea water, and after that we included the previous
materials mentioned for each group.
2º-. Once the mixture was homogenized, we put it
into a test tube. Secondly, we mixed 100g of sand and 20g Rio San Pedro
sediment, with sea water. Both mixtures’ texture should be like milkshake’s
texture.
3º-. After that, we added the second mixture to test tube until we filled
up to 2/3 of the test tube. We left the mixture stand a little bit.
4º-. Finally, we
added 2-3 cm of sea water on the top.
Hypothesis
5A: When
the project has finished, we won't find aerobic bacterias owing to the plenty
sources of N and S. In our column, two predominant colors will be found. In the
lowest part of the test tube, there will be a black color which is caused by
bacterias with a more anaerobic metabolism (respiration S2O3-
-> H2S). It will take up about 1/3 of the solid part of the
column. Above it, we will find a grey color, which is caused by other anaerobic
bacterias (respiration NO3- -> NO2- -> N2).
6A: In conclusion,
after having thrown to the column CaCO3
(calcium carbonate) and Agar the sample
will keep the color it has because it does not have sulfur and although this in
the dark it will not turn blue which would be the color it must acquire when
the bacteria feed on sulfur.
7A: We thought that our column will have aerobic
and anaerobic bacterias, due to the two feeding sources, the cellulose from the
paper and the CaSO4. We also thought that our column will change its
color because we will have anaerobic bacterias producing H2S from SO4-.
Then the H2S will react with the iron in the mud to produce a dark-blue
color. Besides, our column is exposed to sunlight.
We will report more about our columns in the next entry coming soon.
A5 Winogradksy Column.
A6 Winogradsky Column
A7 Winogradsky Column
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