UCA_5A_6A_7A: Day 88 Finishing the project

Hi everyone,

This should be our last report about our Winogradsky Columns. As you will see now, the three columns have remarkable changes since we put our last entry.

Evolution of Winogradsky Columns

Group 5A: The red part that was observed in our second entry has moved, and now, it takes a place in the solid part. Now, we found two different zones with two different colors. In the red zone, we can find bacterias that affix nitrogen and in the black zone, bacterias that affix sulfur. Both are anaerobic, however, for those bacterias who affix nitrogen, the toxicity that is caused by O2 is less dangerous. All in all, we conclude what we already thought before, our entire column is anaerobic, but there are two tonalities, which is not what we used to think, since our conclusion was that there would only be one color.

Winogradsky Column 5A group:

 

Group 6A: After three months we see that the column has change a lot, being almost black except in the lower part, that is due to the precipitation of elemental sulfur as a result of the metabolism of the sulfur bacteria that oxidize the H2S to S. Also there are many points which are bubbles of H2S. The black zone is produced by anaerobic breath with sulfate, that produce H2S which precipitate with Fe producing FeS.

Winogradsky Column 6A group:

Group 7A: Our column has changed a lot during this time. First of all, we have seen the appearance of algae and cyanobacteria. This match with our column, because we left it in a light environment. Also, we have noticed that the orange colour in the middle part has increased, this is produced by photoheteroorganotrophic bacteria. We had black colour in the bottom of our column, but in this case it has extended through the column, but it stops in the middle part. This colour is produced because anaerobic respiration with sulfate was produced. Anaerobic bacteria produce hydrogen sulfide (H2S), that with the Fe, they precipitate in a abiotic way creating FeS. This compound makes the black colour in the column. Finally, we still have gas bubbles through the column, probably CO2 and H2S.

Winogradsky Column 7A group:

After all, we have seen the evolution that a Winogradsky Column may have through a period of time. However, it may increase or appear other organism through the column during this time.

I hope everyone enjoy our entry as we enjoyed doing it. 

 

Thanks everyone and keep follow the activity of this amazing blog.

UCA_5B, 6B_1: day 86

After having spent roughly one month in the light, our two columns present highly different characteristics, due to the dissimilar microorganisms that have grown in each one. In order to comprehend the transition from two months of darkness (in both columns) to the light, we'll try to cover their evolution from the very beginning.

4 g sugar column's evolution. The transition from dark to light happened in the last photo.

Control column's evolution. The transition from dark to light happened in the last photo.

At first, in the column containing 4 grams of sugar (and considering it was kept in the dark), chemoheterotrophic were extremely favoured (at first glance, one might think that the osmotic shock would make it impossible for any microorganisms to survive; however, this doesn't seem to be the case, since the last time we checked our column white-yellowish elementary sulfur had appeared, so there had to be some kind of bacteria producing it; we’ll come back to that later).

What the light did to our sugar column.

Despite not being able to see a colour change in the sugar column (owing to the lack of pigments in this kind of microorganisms), we know for a fact that they, indeed, were able to grow: there were huge emissions of gases (be it CO2, H2S or CH4), and this pushed the contents out of the column (along with the water). This could be the action of anaerobic and facultative anaerobic microorganisms (and definitely also organisms performing both aerobic and anaerobic respiration), so it's reasonable to think they could have grown all over the column (perhaps a bit more towards the bottom-center, where the column has been fractured likely due to the gas emission, so considering the oxygen gradient, this was probably the action of facultative anaerobic bacteria). Also, because of fermentation processes, organic acids must have been produced; and it's a possibility that these were used by our next group of anaerobic chemoheterotrophic bacteria (and they might have used the sugar as well).


We could also find FeS precipitates, indicating the presence of sulfate-reducing bacteria that reduce the SO4(2-) (that was obtained from the sulfur source, CaSO4 in our case) to H2S, which then reacted with the iron present in the sediment thus forming iron (II) sulfide. The fact that black sediments could also be seen at the top of the column (and at the bottom, too) seems to reinforce the idea that large quantities of gasses have pushed the column to the top). This didn't happen in our control column, where a black colour was observed only at the bottom, as one would expect due to the anaerobic nature of these microorganisms.

Side by side comparison after 1 month of light.

After we placed both columns in the light, we noticed a very interesting difference between the control and the sugar columns: large quantities of elemental sulfur (which has a yellowish, white tone) were found in the sugar one. We know there are two kinds of sulfur bacteria that can use H2S as a electron donor during anoxygenic photosynthesis: purple bacteria (think Chromatium) and green bacteria (for instance, Chlorobium). Nevertheless, the first one oxidizes H2S to S intracellularly (storing it in cell structures); while the other one produces extracellular sulfur, which is the one which's colour we can observe. Our problem here is that no green hue was to be found (it could have been masked? Maybe the bacteria died after producing sulfur? In theory, it should have been easier for photosynthetic organisms to grow in the sugar column, as the gas emissions produced by chemotrophs would have been used by them). Despite this, it makes sense that the elemental sulfur appeared at the bottom, as this is where H2S concentration is the highest. Yet, we still found something that might have been seen out of place at first: a crystal-like substance at the very top of the column. We think this is none other than sulfur that has made its way out of the column from the bottom propelled by gas emissions.

Sulfur microcrystals?

What happened to the control column the time it spent in the light?

Moreover, we couldn't find cyanobacteria in either column; this makes sense, especially considering that there was no water left in the sugar column (and almost none in the control one), a very important compound for this oxygenic autotrophic bacterium to grow (it's used as an electron donor during light-dependent reactions).


Lastly, photoheterotrophic bacteria (like Rhodospirillum) were found in both columns near the top, judging by the orange colour we observed. It seems they were able to grow more in the control column.

To conclude, if the white compound we found is indeed sulfur, this would support our last hypothesis (photosynthetic bacteria would find it easier to grow in the sugar column), as it indicates the presence of phototrophic bacteria that oxidize H2S.

Day 45.  UCA. Rio San Pedro sedimentWinogradsky columns C2 and C3.

Today, 5th of June many different types of mycroorganisms can be seen inside the columns. Those mycroorganism has been living and multiplying since March in two different life conditions:

-In an illuminated environment, we can see many dark stains with a colour between blue and grey in the bottom of the column. Those stains are formed by anaerobic bacteria that breathe with H2S.
In the middle of the column, an orange stain can be seen. This stain is formed by Rhodospirillum, photohertroorganotrophic organisms.
Finally on the surface of the column we can see many green stains, that are cianobacteria and algae.

- In a dark environment, we can see in almost all the column a really big stain with a dark colour between grey and blue. This stain is formed by anaerobic bacteria that breathe with H2S bacteria. On this stain, we can see some orange stains, that are formed by Rhodospirillum, photohertroorganotrophic organisms bacteria.

According with those results, we can declare that in those different life conditions, we can see the same type of mycrooorganisms in both colums, except, that we cannot see photoautotrophic mycroorganism in the dark enviroment, because those mycroorganisms need light energy to live.

Light environment

Dark environment

Winogradsky Column. Day 45. UCA B1-B2

After almost 50 days since the last time we checked the columns we can see several changes in their composition.

We´ll be talking about the column B1 because the other column got lost at some point along these days.

as we can appreciate, the changes are noticiables:

• there are plenty of places with orange coloration (due to photoheterotrophic microorganism)
• darker areas mainly at the bottom part (because of the action of sulfate anaerobic breathers)
• olive green zones due to anoxigenic microorganism.

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).

UCA_A4_A3_day45

Tube in darkness
We can see that there's air due to the fact that there was too much sustrat and microorganisms have produced CH4 .
In this column all is dark, it has anaerobic bacteriums.

Tube in light
We can see that in the surface, the tube has turned to light brown due to the presence of aerobic bacteriums.

When we compared both columns, we can see that only in the light column has appeared an extract light brown. Therefore, we deduce that the microorganisms that have grown there, are photosyntetic.

 Darkness                                                                                                           Light