Title of Movie: Growth Conditions for Cyanobacteria
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Cyanobacterial Growth Cyanobacteria are able to feed on three different energy sources. Sunlight, sugars and sulfur compounds. This is really extraordinary. 7 7
Some organisms like animals can only feed on sugars. Others, like plants, feed on sugar and sunlight. Some bacteria feed on sulfur compounds. But it’s really rare for any organism to be so adaptive. In this experiment, I tested three different growth media for a Cyanobacterium called Anabaena. No glucose, Glucose and Glucose with Thiosulfate.
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I also tested the different light conditions. Complete Darkness, 24h light and 16h light, 8h dark.
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To make the growth media I started with a master mix which included the following materials:1g Sodium Nitrate, 0.1g Calcium chloride, 0.3g Magnesium Sulfate, 0.3g, Potassium Monohydrogen Phosphate, 0.7g Potassium Dihydrogen Phosphate, 0.1g Sodium Chloride. I dissolved each of the compounds in 40ml water. I then took 10ml out of each solution and put in a 1L volumetric flask filled up with water.
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Aside from that, I put 1g of ferric chloride in 100ml water. Then I added 1 drop of this 1% solution to the master mix.
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The next step was taking out 3 portions of 300ml master mix each.
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For the no glucose, I added 4.5 g of agar. Agar is a kind of jelly that solidifies the growth medium.
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For the glucose condition I added 4.5g agar plus 0.3g glucose, which is a type of sugar.
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For the last condition, I added 4.5g agar, 0.3g glucose and 3ml of a 2.5% thiosulfate solution, which is a sulfur compound that Cyanobacteria can feed on.
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All 3 growth media were heated on a hot plate to dissolve the salts completely.
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They were then autoclaved at 17psi(pounds per square inch) and 127 deg oC
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This sterilized the growth media and caused the agar to jell.
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Once the growth media cooled, I 6 poured thin layers of each into sterile Petri dishes. Working quickly to avoid contamination.
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As the plates cooled, the agar hardened, which allowed me to put 1ml of Anabaena culture on each.
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I took a third of the plates with each medium and put them in a dark cabinet, another third under 24h light and the last third near a
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window, where it would get close to 16h light. After a day, there was already a difference between conditions. I saw a little growth on No glucose medium, more on Glucose and lots on Glucose plus thiosulfate. The plates kept in the dark showed the least growth. After a week, I took 3 of each different condition and put it under a microscope. The glucose in thiosulfate in 24h condition grew far more than the condition in the 16h and the Dark one. 150 No Glucose Glucose Glucose+thiosulfate
No Glucose Glucose Glucose+thiosulfate
I also looked at the condition with a naked eye and saw that the anabaena was completely spread out. The reason for the significant growth is because of the glucose and Thiosulfate. After another week, I looked at each of the different conditions and my final results showed that the Glucose plus Thiosulfate in 24 hour condition grew far better and faster.
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