UCA_4B_3B_day85

UCA_4B_3B_day85  

San Pedro's River sediment + 0.3 g paper + 0.1 g CaSO4

Group 3B: Alvaro Lucero Garófano and José Luis Hernández Fernández.

Group 4B: Paula Gilabert Prieto and Pilar Grosso Rodríguez.

We have bad news for you, today is our last post.... :(

Our column has been changing during these days since the last time we saw them and we posted it.

The changes produced are:

Column in contact with light:

We can appreciate a change of color from brown to orange. That color manifestate the appearance of the bacteria Rhodospirillum which is photosynthetic

On the other side, we can see some green spots which we think they are algae. Also in this part we can appreciate some black spots at the bottom, which means that are anaerobic organisms.

Column without light contact: 

The only change that we can see, is that the difference bettween anaerobic and aerobic is more defined.

UCA_7B,8B_1: Day 44

Winogradsky column- Day 44

Group 7B (Lucas Garín Ortega and Alba Mejías Gallardo)

Group 8B (Laura Lucena del Amo and Noelia Moares Fernández)

After 44 days, we have checked our columns and we have observed a few changes.

The column made by group 8B, the one exposed to sunlight, didn't have a lot of changes. We could see that the layer of  lighter color previously seen was bigger than before, that means that there were more photoautrophic microorganisms. Also, we could appreciate that there were more bubbles, formed by the sugar fermentation of microorganisms chemoheterotrophs.

Group 8B column

The column made by group 7B, the one kept in the dark, has suffered the following changes. We could appreciate that the column was darker due to the H2S breathing of bacteria. The water on the surface has cleared and an orange layer has formed on the surface. This could be because of the proliferation of photoorganoheterotroph microorganisms. Last but not least, a lighter spot has been formed from a bubble generated by microorganisms breathing.

Group 7B column

UCA_C3-C4_day44

A few weeks after the preparation of the column, we observed both of them, and we noticed some changes.

The C3 group’s column presents the following characteristics:

• The orange spots are photoheterotrophic microorganisms, which use as power source the solar energy, and reduced iron.
• At the surface, we could find green algae and cyanobacteria, since they need oxygen to perform the cellular respiration and sunlight to make the photosynthesis.
• Along the column, we could find tiny white spots, which can be elementary sulfate.
• We could also see small bubbles, which can be due to the fermentation of the chemoheterotrophic micoorganisms.
• We can appreaciate along the column some black spots, which are more intense at the bottom of it. They are due to the anaerobic microorganisms, being stronger as the oxygen gradient decreases.

The C4 group’s column differs from the C3’s in the following characteristics. The rest of the microorganisms are the same as the other one.

• We can find along the coloumn oxidizing bacteria.
• The photoheterotrophic microorganisms of the column use as carbon source the cellulose of paper, and as power source the sunlight.
• It doesn’t present white spots since it didn’t contain sulfate.
• The orange spots are bigger, because of the cellulose that the paper provided.

UCA_A1, A2: Day 44

In our Winogradsky Column we can see a lot of colours that correspond to very different kind of microrganisms. On the top we can see a big green stripe, that corresponds to algas and heterotrophic bacteria. Under this stripe there is a little orange bubble and we suppose that corresponds to an iron oxidizing bacteria. Under that we can see  amounts of scattered red purple colour, a part localized just under this bubble and another part almost in the bottom of the column. The part wich is localized just under the bubble corresponds to non-sulfure bacteria and the other part corresponds to sulfure bacteria.

Alga obtains energy and carbon by doing photosyntesis  using the light energy and the water. Iron oxidizing bacterias use Fe²⁺ and CO₂.  Non-sulfure bacterias use organic carbon and light energy. Sulfure bacterias use H₂S, light energy and CO₂ that produced from the CaCO₃. The CaCO₃ and the water were introduced in the column and the iron can be contained in the mud. We also must remember that microorganisms that grow on the top have more oxygen and less sulfure and the microorganisms which are in the bottom have less oxygen and more sulfure.

UCA_5B, 6B_1: Day 44

44 days have passed since we last checked our Winogradsky columns. In the column without sugar we can observe that some black sediments have appeared. That indicates the presence of anaerobic microorganisms (as sulfate-reducing bacteria) which produce H₂S from CaSO₄ (that served its purpose as a sulfur source). This compound finally reacts with the iron present in the sediment of Rio San Pedro, producing FeS, known for its black color. What's more, there's still some water remaining in this column. 

As the columns were placed in the dark we can’t notice the presence of photosynthetic microorganisms in neither of them.

​On the other hand, in the column with sugar we observe that the same anaerobic microorganisms that appeared in the column without sugar have appeared in this one too. 

Furthermore, we can see that some type of fermentation has happened (due to the fact that the water we found in the previous column has been pushed out, likely because of an excessive emission of gasses, such as CO2), and we could in theory be able to determine its kind. In order to distinguish between lactic and alcoholic fermentation, we should have conducted some analytical experiments that we couldn't afford to do. Despite not knowing exactly what kind of fermentation it was, we can definitely confirm our hypothesis: if there are yeasts in Rio San Pedro (which has been proven to be right), in presence of sugar they'll undergo fermentative processes. 

Thus, we can conclude the experiment was successful and our hypothesis was accurate too.

We've already tested and confirmed our initial hypothesis, so for now on the columns will be placed in the light for further observations. We expect to find some photosynthetic microorganisms that may (or may not) benefit from the increased growth rate found in the column where we placed 4 g of sugar (no more, no less). Considering the enormous emissions of CO2 (coming from either fermentation or cellular respiration) in the sugar column, we believe this could help photosynthetic microorganisms proliferate, which capture and reduce CO2 in order to grow, as shown in the following animation.

Hence, we estimate a greater growth rate of photosynthetic organisms in the sugar column, compared to the control one (that has no sugar at all).