Winogradsky
Columns
Acidic column (column A) and column with an
alternative source of sulfur (column B)
Team; Cheiladakis Emmanouel, Grizi Olga,Varoucha Effrosyni
Sampling
Sampling was carried out at Koronisia, Amvrakikos Bay
(Greece) on 20/10/2017. Three columns were made; one as the control, one with
low pH (pH=3), and the last one containing an alternative source of sulfur
(rice). The nutrients used are presented below:
Control
column
|
Column
Α
|
Column
Β
|
|
Egg
(sulfur source)
|
25
g
|
25g
|
-
|
Newspaper
(Carbon source)
|
1
g
|
1
g
|
1
g
|
Mud
|
1/3
of
the bottle
|
1/3
of
the bottle
|
1/3
of
the bottle
|
Mud
with added nutrients
|
1/3
of
the bottle
|
1/3
of
the bottle
|
1/3
of
the bottle
|
Lagoon
Water
(pH=8.5)
|
350
ml
|
350
ml
|
350
ml
|
Lemon
Juice (pH=3)
|
-
|
100
ml
|
-
|
Rice
(sulfur source)
|
-
|
-
|
150 g
|
.The rest of the bottle stayed empty, in order for aerobic bacteria to grow
After the sampling process, the columns were placed in
an accessible by light spot, at room temperature. The duration of the
experiment was approximately 3 months. Through this period the columns were
compared by the appearance of colour layers.
Pic.1;
Typical colour zones due to bacterial growth in a Control
Winogradsky column.
Hypotheses
-
In column A, pH value was stabilized at 3, where fermentation is not expected to occur in the lower layers as the fermentation bacteria (e.g Clostridium) cannot survive. As a result there is no carbon acids (which are produced by Clostridium) for sulfate-reducing bacteria to grow. This prevents or reduces the appearance of the upper layers. Also, due to the acidic environment, neither cyanobacteria will grow. In this case, no colour pattern is expected.
-
The same amount of sulfur was added in column B, using rice as a source, and if bacteria use it in the same way, we do not expect significant differences in the colour pattern between the control and the column B.
Pic.2; Hypothesis A- What is expected to happen in the acidic column
Results
A.Hypothesis
accepted; there was no zone observation because acidic pH prevented the
growth of the expected micro-organisms.
B.Hypothesis
rejected; there was also no zone
observation, so it was proven that bacteria don’t use the sulfur
from the rice in the same way they use it from the egg.
It needs to be clarified, though, that there is a possibility low pH or rice as a sulfur source just delayed the growth process and not completely prevents it. So in order to be absolutely sure of the result, observation for a longer period is essential.
Phases
of the experiment
ü In every photo column B is at
left,control column is in the middle and column A is at right.
Pic.3;
Winogradsky
columns-
Day
1
Pic.
4; Winogradsky columns- After 2 months
Pic.5;
Winogradsky
Columns- Final Phase
Nice and original presentation! Any estimation on rice sulfur content compare to egg? Approx pH value at the end of the experiment?
ReplyDeleteThank you! We found that 100g boiled egg contain 180mg S, while 100g boiled rice contain 30mg S. So eggs have six times more sulfur content than rice. For this reason, the control and acidic columns were enriched with 25g boiled egg each, while column B was enriched with 150g boiled rice.
DeleteThe pH value was 5 after two months, and the last week finally reached up to 7.
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