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

WEEK: 7th

LEFT: warmth-exposed

RIGHT: control

   Warmth – exposed column                                          Control column

  

  Between the 6^th and 7^th week, we couldn’t descry any obvious difference.

  The growth of the purple sulfur bacteria in the middle zone is still more visible in the control column than in the warmth-exposed column. During photosynthesis, unlike cyanobacteria or plants, they bind sulfur from the bottom of the column producing hydrogen sulfide, rather than oxygen. Thus, the purple sulfur bacteria cause anoxic conditions in the middle zone they grow.

  In both columns, is still observed the presence of biofilms, the concentration of which, is greater in the first column.

  This gradual distinction in the zones of the column, starting with the display of sulphates purple bacteria, has only been observed in the control column, even after 7 weeks. Thus, it can be assumed that the growth rate of the bacteria in the 2^nd column, is considerably slower, as zoning hasn’t been observed yet. This fact is probably due to the rapid fluctuation of temperature. In the warmth-exposed column, this affects the bacteria directly by limiting the growth of the non-resistant ones at high temperatures. Also, the bacteria in this column, in order to get protected from the temperature fluctuation, could form spores, which means a static metabolic condition. Rather than that, the overheating of the plastic bottle can excrete damaging chemicals for the bacteria.
  

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