Department of Biological Applications and Technologies, University of Ioannina
Experiment
We constructed two Winogradsky columns with mud and water from the lagoon in Koronisia, in 20th October 2017. We used newspaper as a carbon source and egg as a source of sulfur and carbonate ions. In one column we also added 50gr of salt to check how it would affect the growth of microorganisms.
Hypothesis
We expect a delay in the bacterial growth in the salt-enriched column but similar colour patterns.
Our
hypothesis is based on the fact that in every broad taxonomic group
there are halophilic species, therefore no significant difference will be
observed in the colour patterns. Possibly
the diversity of the high-salinity column will be more limited, but this can not be deduced with simple observation, unless a group is completely absent. Also,
due to the increased salinity, the number of microorganisms that
survive and consequently grow in this column will be lower compared to
the standard and therefore the formation of colonies will be delayed.
Results
Our hypothesis was rejected, since we observed the same rates of bacterial growth in both columns. This could be due to the fact that the mud we collected exhibited high salinity (about 80‰) so halophilic species were already abundant in it, and the addition of salt didn't significantly change their growth conditions.
As it can be seen in the pictures that follow, the colour patterns are similar in both columns throughout the experiment but the colour of the water differs (reddish in the standard column and muddy in the salt-enriched one).
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| Standard, 26/11/17 |
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| Salt, 26/11/17 |
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| Standard, 23/11/17 |
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| Salt, 23/11/17 |
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| Standard, 14/12/17 |
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| Salt, 14/12/17 |
Did you measure/estimate salinity after addition of NaCl?
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