Dark Column: Probably column changes are not too remarkable this time, they could be group as a colour darkening. It could be due to an increase bacteria concentration. Top layer is unchanged.
Here, we include an explanation of why dark colour is produced:
Dark area growth indicates the presence of two types of bacteria. Desulfovibrio and Clostridium.
Desulfovibrio genus bacteria uses both by-products
of the fermentation carried out by genus Clostridium anaerobic respiration and sulphate
salts added in the sediment, generating large amounts of H2S in the
process. This H2S reacts with iron present in the sediment,
producing ferrous sulphide which justifies the black colour.
As said before, dull area progressively expands. This is caused due to Clostridium strictly
anaerobic condition (it will die in presence of oxygen). As oxygen which is
still contained in the sediment disappears, population will be more spread,
producing more metabolites (ethanol and organic acids). This contributes with
the increase of Desulfovibrio population thus producing more SH2 and
iron sulphide, obscuring that area of the column.
Clostridium bacteria metabolize the cellulose which
comes from paper in order to produce glucose. Afterwards, by fermentation, energy
will be gained, obtaining these metabolites in the process.
Light column: Water has become orange, mollusk died and bateria dominate the column. In the light zone many bacteria have grown while in the dark zone there is nothing. We can see all around the bottle a very intense orange due to iron oxide. In the bottom we see again the sulfate-bacteria that produce the dark colour and we can also see violet spots that tell us there are sulfure-bacteria.
No comments:
Post a Comment