UCA_C5_C6_C7 day 90

C6: Ana Valdivia Aceituno, Curro Polo Castellano y Sergio Valiente Vélez.

C5: David Ruiz Romero y Carlos Pinto Perea.

C7: Noemí Toro Barrios, Nerea Rojas Sanz, Jose Manuel Pozo Suárez.

Hi everyone!

Here we are going to compare de progress of our Winogradsky columns from the day 44 till the day 94 after beginning this experiment. As we can see, the columns have suffered too many changes. The matter that we agree at the beginning has already been consumed.

Figures 2: 90 days

Figures 1: 40 days

C6: 0,25 g paper +0,25g CaSO4 + Sun light

C6 column has experimented a differentiation of the organization of microorganism with the pass of the time:

On top, from 40 days till today: we can find a green colour that indicates the presence of cyanobacteria; they need to be in the surface to catch gasses like O₂ because they perform oxygenic photosynthesis. This colour can also indicate the presence of algae.

Bellow this, we can see an orange colour that indicates the presence of photoheteroorganotrophs organisms (for example: Rhodospirillum). They use sunlight as a principal source of energy and organic matter from outside as a source of carbon.

This organic matter should come from cyanobacteria of above because they produce secondary metabolites that are sent out when they don’t need them anymore.

Below the orange area of the column, a dark region is placed. Its black and grey colours are due to the existence of anaerobial breath which produces a precipitate of FeS or Fe.

There are also some gas bubbles whose composition can be methane, carbon dioxide or hydrogen sulphide.

The pink region of the column, which is placed under the grey and black one, is probably where Chromatium are placed. As we can compare, this region is bigger whit the time.

Finally, in the very bottom of the column there is a dark green region associated to Chlorobium as they are green bacteria which are anaerobial and phototrophs.

Now, let’s talk about C5 column: The column is still dark on the 20 of April.

Figure 1:40 days

On the one hand, one face of the column is less dark than the other face because it has been exposed to the sun.

On the other hand, in the centre we can see a brown spot that maybe due to pollution. Eventually, there is water in the top.

Along the column it can be observe the presence of purple sulphur bacteria, anaerobic photoautotroph anoxygenic organisms that live at the bottom of the column.

It can also remake the fact that all the initial glucose has been converted to hydrogen sulphide.

Then, on June 1 our Winogradsky column hasn’t changed.

Figure 2:90 days

The dark area covers practically the entire column. This black zone is compound of anaerobic respiration with sulphate, producing hydrogen sulphide which precipitates iron with abiotic form as black iron sulphide.

One side of the column is less dark than the other because it has been exposed to the sun.

Continuing with the observation, in the centre we can see brown spots that may be due to contamination. Sometimes, there is water in the upper part of the column and dry remains of gases that have emanated from the surface liquid (methane, hydrogen sulphide, carbon dioxide ...).

Throughout the column, the presence of purple sulphur bacteria can be observed; anoxygenic photoautotrophic organisms (of the Chromatium type) that live in the lower part of the column. It may also be because all the initial glucose has been converted to hydrogen sulphide.

By the end, the column C7 has been changing a lot throughout these days:

Figure 1: 40 days

Figure 2: 90 days

 First; it shows a brown colour. Some crevices can be seen in the sediment, as well as, dark grey spots. These crevices may show up because of gas production such as CO2, CH4, H2S... Furthermore, orange spots can be seen too, which indicate the presence of photoautotrophic organisms.

It has divided in two parts: a lighter one and a darker one. It must be because the sunlight only lights up in the lighter one. So, we think that in the lighter one there will be more photoautotrophic organisms while in the other will be more chemoautotrophic organisms. The darker one should be formed by organisms that reduces sulphur because the colour black indicates us that it contains sulphur.