STUDENTS:NENA KOUKOUGELI
                        DIMITRA-IOLI SKOUROLIAKOU
UNIVERSITY OF IOANNINA GREECE
BIOLOGICAL APLICATIONS AND TECHNOLOGY
AQUATIC MICROORGANISMS

WEEK: 5th

LEFT: control

RIGHT: warmth-exposed

The differences between the two columns are more obvious from the 4th to the 5th week.

In the first column, have grown purple sulfur bacteria in the middle zone. They grow in the middle zone because they need to access the sulfur coming from the bottom of the column and be close enough to the sun for the photosynthetic process.

During photosynthesis, purple sulfur bacteria bind sulfur from the bottom of the column and produce hydrogen sulfide. Subsequently, the hydrogen sulfide is oxidised to elemental sulfur and stored in the internal sulfur granules. Thus, and considering the fact that these bacteria cannot produce oxygen, the purple sulfur bacteria cause the anoxic conditions to the area they have grown in, namely, the middle zone.

In both columns, is still observed the presence of biofilms, the concentration of which, is greater in the first column Also, in both columns the sludge is darker from the previous week, due to the anoxic conditions now that in the presence of sulphates purple bacteria will begin to exaggerate rapidly.

After 5 weeks, it has started a gradual distinction in the zones of the column, starting with the disply of sulphates purple bacteria. Considering that the forementioned zoning hasn't been yet observed in the 2nd column we can safely assume that it's groth rate is considerably slower. This happens probably due to the rapid fluctuation of temperature that affects the bacteria, not only directly by limiting the growth of the non-resistant, at high temperatures, bacteria, but also it affects them indirectly by the overheating of the plastic bottle that excretes damaging chamicals.

Hypothesis: The rapid fluctuation of the temperature on daily basis, reduces the growth rate of the microorganisms in the 2^nd Winogradsky column.