A higher zone of green colour where cyanobacterias and algae that liberate oxygen to environment are situated keeping this zone aerobic.
The second zone is of purple colour, we can find sulphate reducing bacterias, this bacterias give purple colour to this zone. Sulphides are liberated by bacterias to oxygenated highes zone creating a gradient where photosynthetic bacterias that use sulphur are developed.
Finally in the lower zone, what is of black colour there are micro-organisms that make anaerobic breathing or they make fermentatives process producing alcohol and fatty acids like subproducts of their metabolism. This products are substrate to growth of sulphate reducing bacterias.
In conclusion we noticed that a gradient of oxygen and an interdependence between zones of column with different micro-organism is established like we thought.
In the Winogradsky's column put in the dark, no micro-organism have been developed since they need light as energy.
The third week:
One month later:
Nice colours.
ReplyDeleteI can assure you that in the dark, the column is full of bacteria. You do not see colours (as many as in the light) because the colours in the column in the light are produced by the pigments that photosynthetic bacteria produce to capture the energy from the light.
Also in the light the pink colour is from purple sulfur bacteria, not sulfate reducing bacteria. The latter produce hydrogen sulfide that is being used by the former. Your poop is my food.