In the first
week, we can see a black colour at the bottom of the column. This is a result
of sulphydric production. Besides, there is water in the top of the column,
where we can find an orangey brown colour (this is the zone provided with
oxygen). Moreover, consequently to have
added a lot of mud and just a bit of sand, there is a part in the middle of the
column that is completely grey and homogenous, where gases can’t pass through
it. Due to this point, we can guess that there will be two separated
communities.
In the
second week, we observe that the homogenous part has decreased. Besides, we see
a black colour in the top of the mud (there are bacteria that feed of sulphate
and produce sulphydric acid). In another hand, the brown community are bacteria
that are able to use oxygen.
After two
weeks, we focus on our column again. As a result of have added a lot of mud,
the development of the microorganisms is
very slow. The continuous black colour indicate us that bacteria keep producing
H2S. Now, there is an orange colour that is a signal of the
existence of photoheterotrophs microorganisms producers of iron.
Nice to see the succession of pictures. The orange rusty colour is different in the three weeks? What do these photoheterotrophs actually do? They certainly do not produce iron...;-) although that would be useful for us.
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