UCA_E7-8_3: 9th week.

In the last stage, approximately nine weeks later, the winogradisky column presents significant changes in each of the zones. In this image we can see, the different areas of the column, increasingly differentiated.

Column WITH sunlight:

The column on the left is the one exposed to sunlight, where we can see four distinct areas. Comparing this, with the column of six weeks, the colors are much more differentiated.

In the lower part we can see some pink spots and less white spots in a dark sediment. In week six there were less white spots and there weren’t pink spots. This is due to the anaerobic conditions in which microorganisms are found and they have less nutrients to survive, keeping alive the microorganisms more evolved and better fighting for nutrients. We think that the fermentation without oxygen, or anaerobic has come to an end, becauseall the organic matter, in this case, the sulfur in the form of gas, has been converted by the microorganisms in H2S. This column portion is very voluminous, and occupies about half of the column.

At the top in the region 2L the hydrogen sulphide from the bottom is consumed by anaerobic bacteria. In this week, the column presents that zone much smaller to week six because the sulfur has been consumed almost in its entirety. It still retains its black color.

In zone 3L we see a green color with brown tones, this zone has presence of sulfur and oxygen. It is aerobic because various bacteria oxidize the sulfur present in lower zones. There is not enough sulfur in the middle and it has completely oxidized and for this reasonit has green color.

In zone 4L is where the microorganisms are in contact with the oxygen, the aerobic zone. In this case, zone 4L is not the smallest. This time zone 2L is the smallest.

Column WITHOUT sunlight:

This column presents microorganisms which don’t use sunlight for their vital functions, that is to say, are chemosynthetic bacteria that elaborate their own food from the energy of the substances that contain iron, hydrogen, sulfur and nitrogen.

Zone 1R is where organic matter is transformed by bacteria into sulfur. (Black)

Zone 2R is also black. Sulfur is consumed by bacteria, consequently, there is no intermediate zone that oxygenates the sulfur. This area is anaerobic.

The 3R zone is aerobic and here we find bacteria that transform the oxygen present.

In conclusion, in the column without light we didn’t observe significant differences of bacterial growths compared to the column with light, in which we have seen a bigger growth of microorganisms well differentiated and of different types.

Ana García Ramos, Carlota Borne Bernal, Ernesto Segundo Mendoza, Maria del Carmen Espinosa Corona and Pablo Carrasco Ercilla.