Week 2 Observation

The most obvious colours observed in all the containers are red, green and rust-liked colour. Why there are different coloured zones? Center on Disabilities Studies (n.d.), these coloured bands came from the pigments of billions of photosynthetic bacteria grown in the different gradients of oxygen and hydrogen sulfide throughout the container. There are two different groups of microorganisms:

•          Photoautotroph- organisms that use light to incorporate inorganic carbon into cellular material.
•          Photoheterotroph- organisms that use light to transform organic carbon into cellular material.

The amount of the nutrients, oxygen and also temperature differs throughout the container. The very top of the container has access to oxygen continuously while the bottom part of the container accumulates hydrogen sulfide which is formed by microorganisms living in oxygen scarce environment. The picture below illustrates the oxygen and hydrogen sulfide gradient and the microbial zones based on their distinctive colour.

Figure 1: Winogradsky column on oxygen and hydrogen sulfide gradient and microbial zones (Center on Disability Studies (CDS), n.d.)

Figure 2: Blank container.

               Based on Figure 2, the topmost part of the container appears to be slightly green, then into the rust-liked colour and a layer of red black at the bottom layer. Based on CDS (n.d.) the colour presence is further explained in the table below

Table 1: The colour and the possible types of microorganism present in the blank container.

Colour	Zones	Type of microorganisms
Grass green	Aerobic -Oxygen rich part of the container	Algae or photosynthetic cyanobacteria. These bacteria have photosynthesis like that of plants.
Rust-liked	Microaerophilic -Oxygen scarce zone	Purple sulfur bacteria such as  Rhodospirilum and Rhodopseudomonas.
Red and black	Anaerobic -Oxygen depletion	Sulfate reducing decomposers Chromatium that changes from red to purple layer due to processing sulfates into sulphur. Other decomposer is Gallionella; that creates the black layer after processing iron.

Figure 3: Container with heavy metal (copper).

            Based on Figure 3, green colour appears at the top and then slightly rust-liked colour in the middle and red and slightly black at the bottom. Based on CDS (n.d.) the colour presence is further explained in the table below

Table 2: The colour and the possible types of microorganism present in the copper container.

Colour	Zones	Type of microorganisms
Grass green	Aerobic -Oxygen rich part of the container	Algae or photosynthetic cyanobacteria. These bacteria have photosynthesis like that of plants.
Rust-liked	Microaerophilic -Oxygen scarce zone	Purple sulfur bacteria such as  Rhodospirilum and Rhodopseudomonas.
Red and black	Anaerobic -Oxygen depletion	Sulfate reducing decomposers Chromatium that changes from red to purple layer due to processing sulfates into sulphur. Other decomposer is Gallionella; that creates the black layer after processing iron.

Figure 4: Container with fertilizer.

The container with fertilizer as the contaminant shows green colour at the top, followed by rust-liked colour , and red a little black at the bottom of the container. Based on CDS (n.d.) the colour presence is further explained in the table below

Table 3: The colour and the possible types of microorganism present in the fertilizer container.

Colour	Zones	Type of microorganisms
Grass green	Aerobic -Oxygen rich part of the container	Algae or photosynthetic cyanobacteria. These bacteria have photosynthesis like that of plants.
Rust-liked	Microaerophilic -Oxygen scarce zone	Purple sulfur bacteria such as  Rhodospirilum and Rhodopseudomonas.
Red and black	Anaerobic -Oxygen depletion	Sulfate reducing decomposers Chromatium that changes from red to purple layer due to processing sulfates into sulphur. Other decomposer is Gallionella; that creates the black layer after processing iron.

Figure 5: Container with cooking oil.

The only different result was obtained from the container with the cooking oil as the contaminant. The container shows red in colour at the top, followed by green for the next layer, then later rust-liked in colour. Based on CDS (n.d.) the colour presence is further explained in the table below

Table 4: The colour and the possible types of microorganism present in the fertilizer container.

Colour	Zones	Type of microorganisms
Red	Microaerophilic -Oxygen scarce zone	Purple sulfur bacteria such as Rhodospirilum and Rhodopseudomonas.
Green		Green sulfur bacteria such as Chlorobium. The green/olive colour indicates growing anaerobic conditions.
Red and black	Anaerobic -Oxygen depletion	Sulfate reducing decomposers Chromatium that changes from red to purple layer due to processing sulfates into sulphur. Other decomposer is Gallionella; that creates the black layer after processing iron.

References

Microbial Ecology, Center on Disability Studies, University of Hawaii,[pdf]. Available from: http://www.cds.hawaii.edu/kahana/downloads/curriculum/SectionII/Unit9/9.A.MicrobialEcology/9.A.2.MicrobialEcologyProject.pdf

The Winogradsky Column, Center on Disability Studies, University of Hawaii,[pdf]. Available from: http://www.cds.hawaii.edu/kahana/downloads/curriculum/SectionII/Unit9/9.A.MicrobialEcology/9.A.2.MicrobialEcology.pdf