GMU:BioArt WS16/Freya Probst

Basic growth medium for bacteria

How can we, as people without access to a professional laboratory, grow microorganisms?

1. Procedure:

The petri dishes are cleaned with a solution of 70% Alcohol + 30% of water.

   200   ml destilled water/ tapwater
   3 ts  sugar
   2 ts  bouillon/ peptone (proteins)
   2 g   agar (gellant)

We mixed different mediums, varying the ingredients. Tapwater and bouillon are easily accessible, while peptone and destilled water are more specific.

Mine contained distilled water, but instead of peptone I used bullion.

2. Outcome:

Only the soil sample showed some result. Besides that we can only observe oil drops from the Boullion.

Bacteria tasting

Fermentation is a way of preserving food and the reason for that lies within its sour flavour. Under these sour conditions, neither mushrooms nor bacteria (other than our Lactobacillales) will grow. In our stomachs Lactobacillales takes over important functions and we won't kill it by drinking it. However after taking antibiotics humans can repopulate their gut flora by eating or drinking something probiotic.

1. Milk -> Yoghurt:

   kill possibly pathogenic organisms in the milk: 90°C
   cool milk down to body temperature: 40°C
   add the Lactobacillales (in a few spoons of yoghurt)

Inside of the incubator the bacteria eat the lactose found in the milk.

2. Kombucha Tea:

   1 cup  black/green tea
   4 ts (or more)  sugar
   add lent or bought Gluconacetobacter xylinus (after the tea cooled down to room temperature)

Serial dilution of bacteria

Under the right conditions one Bacteria can divide itself infinetely and pile up a colony of its kind. The procedure of serial dilution (reducing the amount of bacteria in a solution within steps) is for example useful for counting bacteria. The Gluconacetobacter that we extracted out of the Kombucha Tea also changed its colonies with different concentration of bacteria in a solution (distilled water).

1. Medium for the Gluconacetobacter:

   10 g     Glucose
   2.5 g    Peptone
   2.5 g    Yeast extract
   1.35 g   Na2HPO4
   0.75 g   Citric acid
   500 ml   Distilled water
   7.5 g    Agar

2. Dilution Procedure

We had 6 Petridishes that contained our medium and our pipette could collect 3 ml of liquid. As a first step, we blended a piece of the Kombucha skin with 0.5 ml of distilled water and poured a drop onto our first dish. The first 0.5 ml of bacteria-solution was diluted further with additional 2.5 ml of distilled water. Another drop was poured onto the second dish. We emptied the pipette again till we regained the amount of 0.5 ml and added another 2.5 ml of distilled water.

3. Outcome

1:1	1:6	1:36

1:216	1:1296	1:7776

We could observe how the Gluconacetobacter colonies arranged differently according to its concentration on the petridish.

Oil Immersion

Oil immersion is a method of microscopy, which in our case, increased the resultion another 100 times.

1. Looking at the microscopes lenses

   Ocular     10 *  magnification
   Lense 1     0 * (in addition to the Ocular = 10* magnification)
   Lense 2   10 * (*10 = 100)
   Lense 3   40 * (*10 = 400)
   Oil Immersion Lense 100 * (*10 =1000)

Our sample is placed on a microscope slide and protected by a cover slide. After mounting the slide onto the microscope we added a drop of immersion oil and turned the lense to face our sample. The tip of the lense was then in contact with the drop on our slide.

Glucenacetobacter xylenius