Winogradsky Column - Sediment Separation
Name: Petros Prapas
Facility: University of Ioannina
Department: Biological Applications and Technology
Sampling site
The sediment samples were collected at Kalodiki swamp on October 16th. During the mid-Autumn season most of the lake's surface is dried out, yet a small pool of water remains on the northern side providing the surrounding gravel with moisture. These conditions create an ideal environment to study the sedimental microbial diversity as the absence of surface water restricts the vertical oxygen flow through the mud resulting in more intensive zoning, more diverse conditions and higher microbial abundance. A big and diverse initial population is expected to boost the effectiveness of the experiments.
Hypothesis
The periodic fluctuation in climate have a direct effect on the aquatic ecosystem. The microbes adapt swiftly on the new conditions but their dependence on specific factors results in different populations thriving during the hot Summers or the Spring floods. Even the day-night consecution could work as a restricting factor for some species regulating the whole ecosystem. In order to prove or disprove this hypothesis we need to compare a stable to an unstable ecosystem concerning the temporal variations in daylight, temperature and other factors as climate conditions. When examining the more stable experiment we expect to observe less and more distinct microbial marks.
Methods and materials
Containers: 2 plastic bottles
C source: Paper
S source: 3 Pre-boiled chicken eggs (yolks and whites)
Media: Muddy sediment enough to fill the bottles
Lake water
The filling materials were evenly mixed.
The bottles were filled up and let to rest for 5 days before they were put in their spots.
Bottle 1 was placed outdoors in a spot that has about 8 hours of direct sunlight daily. Bottle 2 was placed in a handcrafted water bath with stable conditions of 20oC provided by a commercial aquarium heater and light all over the day by a daylight simulation lamp. The conditions were monitored daily.
The bottles were settle to rest for approximately 3 months before they were observed and cleaned out.
Results
Regarding the microbial abundance, the results were minimum due to a major problem. Over the course of the experiment a seperation of the water phase was observed. Specifically, during the 3rd week 3 phases could be identified in both ocolumns: 1. fine clay mixed with water (bottom), 2. pure water with free particles (middle), 3. dense wet mud with distinct gas pockets. The inconsistency of the media seemed to cause the expected optical results to the bottles that did not show any substantial signs of microbial zoning. However, high microbial bacterial action was present on bottle 2 which was in need of air pressure relieve in a daily base throughout the course of the experiment. In bottle 1, high pressure developed over only the 2 first weeks. After that the conditions remained relatively stable.
During the incubation of bottle 2, an attempt was made to identify the rate of the lower phase formation. The upper phase seemed to consist of a solid network of mud clusters that was pushed up vertically by the trapped air pockets. The higher levels that lacked water had a more rigid texture. However the lower levels of the mud that met the water phase were less dense and resembled the clay on the bottom at the bottle. Small movement from the rising gases resulted in the precipitation of small particles ending up increasing the peak of the lower clay phase. A try to define the sedimentation rate by marking the peak of the lower phase showed that an upward movement of the clay was also happening. This lead to the temporary formation of a fourth phase of floating fine clay between the mud and the water phase. This phenomenon could not be explained but it is possible that it is linked to the cluster formation procedure caused by microbial activity.
Bottle 2 showed a dark green formation in the water phase which is most likely green sulfur bacteria. This conclusion is drawn from the fact that even though there was a 24/7 light availability, there are little to no photosynthetic organisms on the top layer of the column which is guaranteed to have an adequate concentration of O2 and CO2. Furthermore, the probability of both photosynthetic and sulfur using organisms developing on the same area is rejected as the oxygen produced by the photosynthetic would cause the thriving of organisms who use O2 as an electron carrier.
In bottle 1 a small print of purple non-sulfur bacteria was observed in the expected position while no green marks were on the lower middle of the bottle. This proves that the O2 was finely graded vertically through the columns and the light had no effect in both cases.
Discussion - Conclusion
This particular experiment raised more questions than provided answers. While the hypothesis was not able to either be proved or disproved, it would be interesting to investigate the reasons why the sediment zoning occurred. Is it a phenomenon that was caused exclusively on the home experiment or does it happen in the natural environment too? It is also possible that it can be a direct result of the microbial activity, as the first indications of sediment zoning came along with the first indications of bacterial development. A new experiment on sediment zoning is going to be conducted over the course of the upcoming months the results of which are going to be posted as a new thread on this post.
Name: Petros Prapas
Facility: University of Ioannina
Department: Biological Applications and Technology
Sampling site
The sediment samples were collected at Kalodiki swamp on October 16th. During the mid-Autumn season most of the lake's surface is dried out, yet a small pool of water remains on the northern side providing the surrounding gravel with moisture. These conditions create an ideal environment to study the sedimental microbial diversity as the absence of surface water restricts the vertical oxygen flow through the mud resulting in more intensive zoning, more diverse conditions and higher microbial abundance. A big and diverse initial population is expected to boost the effectiveness of the experiments.
Hypothesis
The periodic fluctuation in climate have a direct effect on the aquatic ecosystem. The microbes adapt swiftly on the new conditions but their dependence on specific factors results in different populations thriving during the hot Summers or the Spring floods. Even the day-night consecution could work as a restricting factor for some species regulating the whole ecosystem. In order to prove or disprove this hypothesis we need to compare a stable to an unstable ecosystem concerning the temporal variations in daylight, temperature and other factors as climate conditions. When examining the more stable experiment we expect to observe less and more distinct microbial marks.
Methods and materials
Containers: 2 plastic bottles
C source: Paper
S source: 3 Pre-boiled chicken eggs (yolks and whites)
Media: Muddy sediment enough to fill the bottles
Lake water
The filling materials were evenly mixed.
The bottles were filled up and let to rest for 5 days before they were put in their spots.
Bottle 1 was placed outdoors in a spot that has about 8 hours of direct sunlight daily. Bottle 2 was placed in a handcrafted water bath with stable conditions of 20oC provided by a commercial aquarium heater and light all over the day by a daylight simulation lamp. The conditions were monitored daily.
The bottles were settle to rest for approximately 3 months before they were observed and cleaned out.
Results
 |
| Sediment zoning under backlight |
During the incubation of bottle 2, an attempt was made to identify the rate of the lower phase formation. The upper phase seemed to consist of a solid network of mud clusters that was pushed up vertically by the trapped air pockets. The higher levels that lacked water had a more rigid texture. However the lower levels of the mud that met the water phase were less dense and resembled the clay on the bottom at the bottle. Small movement from the rising gases resulted in the precipitation of small particles ending up increasing the peak of the lower clay phase. A try to define the sedimentation rate by marking the peak of the lower phase showed that an upward movement of the clay was also happening. This lead to the temporary formation of a fourth phase of floating fine clay between the mud and the water phase. This phenomenon could not be explained but it is possible that it is linked to the cluster formation procedure caused by microbial activity.
Bottle 2 showed a dark green formation in the water phase which is most likely green sulfur bacteria. This conclusion is drawn from the fact that even though there was a 24/7 light availability, there are little to no photosynthetic organisms on the top layer of the column which is guaranteed to have an adequate concentration of O2 and CO2. Furthermore, the probability of both photosynthetic and sulfur using organisms developing on the same area is rejected as the oxygen produced by the photosynthetic would cause the thriving of organisms who use O2 as an electron carrier.
 |
| Handcrafted waterbath |
Discussion - Conclusion
This particular experiment raised more questions than provided answers. While the hypothesis was not able to either be proved or disproved, it would be interesting to investigate the reasons why the sediment zoning occurred. Is it a phenomenon that was caused exclusively on the home experiment or does it happen in the natural environment too? It is also possible that it can be a direct result of the microbial activity, as the first indications of sediment zoning came along with the first indications of bacterial development. A new experiment on sediment zoning is going to be conducted over the course of the upcoming months the results of which are going to be posted as a new thread on this post.
 |
| Optical results |
Bottle 2 - Could sulfur consumers be photosynthetic (anoxygenic photosynthesis...?)?
ReplyDeleteIt is most likely that the green organisms are green filamentous anoxygenic phototrophs (FAPs) as they seem to be waterbourn in the middle phase and they are not present on bottle 1.
ReplyDelete