University of Cadiz_11B-1B_1: Day 1- The beginning of a glorious empire

Hi everyone!! We are a group of two biotechnology´s students from Cadiz University. We did the Winogradsky column experience two months ago and now we are making public our results. To prepare the column, we just added sediments from Rio San Pedro and mixed it with sea water in a plastic bottle of 1,5L.  Afterwards we exposed our Winogradsky column to sunlight.

We made the Winogradsky column on 23/02/2016. Two weeks later we took the first three pictures.

08/03/2016     (Indirect sunlight exposition) it has appeared orange patches and small black spots.

                       (Direct sunlight exposition) This part has become lighter and now it has a light brown color.

                               

           

            Direct sunlight exposition                       Indirect sunlight exposition                      Half and half

15/03/2016      (Indirect sunlight exposition)  We’ve noticed an important increase of orange patches                            and a descent in the number of black spots.

                         (Direct sunlight exposition) No significant changes.

                             
    

                    Indirect sunlight exposition            Direct sunlight exposition                      Half and half

4/04/2016       (Indirect sunlight exposition) Orange patches have increased even more, we nearly                               can’t appreciate black spots.

                        (Direct sunlight exposition) No significant changes

                        On the surface of the Winogradsky column some algae have grown.

                              

                           Indirect sunlight exposition                   Half and half                           Direct sunlight exposition

Justification

We think that orange patches are rusty iron produced by iron oxidizing bacteria’s metabolism. (Fe²⁺ -->Fe³⁺)

Black spots might be iron sulfides, which could have been made by the combination of rusty iron that we’ve mentioned before and sulfur produced by non-sulfur bacteria.

Algae have grown thanks to the sunlight and the carbon dioxide produced by heterotrophic bacteria, located on the direct sunlight part.

See you soon

To be continued...