OBSERVATION OF BACTERIAL CELLS VIA MICROSCOPE In this experiment, we have learned several basic molecular biology techniques. Here they are; Simple staining: Only one type of dye used for simple staining and it stains all cells the same color. Creating contrast between cell and background to observe cell morphology is aimed. Differential staining: A differential stain uses more than one dye and stains different kinds of organism with different colors. Positive staining: If cell itself is stained it is called positive staining.
It sticks with specimen and gives its color. Negative staining: If background is stained and cell visualized by making use of contrast difference between backgrounds and cells, it is called negative staining. Simple staining Salmonella anatum obtained from liquid broth and agar plate was stained with methylene blue, safranine and crystal violet dyes respectively. Sample taken from agar plate is much more concentrated than sample from broth. We expected to observe the rod-shape for these bacteria and see that this is actually rod-shaped.
Some parts of prepared smears were difficult to observe due to high concentration of smear. It should be washed away during smear preparation. In addition, while performing smear preparation such as high or low heat fixation process or not well washing off excess dye may cause this. Moreover, it is important to be careful when taking sample from agar plate if too much bacteria is taken, it will effect the observation of them. They will look like to attach each others. And we cannot differentiate the shape of bacteria if too much sample is taken.
Temporary wet mount It is a technique in which sample suspending in liquid placed on glass and covered with cover slip. Live cells can be examined under microscope by using this technique. Saccharomyces cerevisiae which is known to be immobile (and 5-10 micrometer in diameter that make it easy to observe) yeast was observed under microscope to observe its movement under effect of so called Brownian motion. Random pattern which is depend on mainly kinetic energy of any cell and concentration differences of them was observed as expected.
Hanging Drop Hanging Drop is microscopic technique used to determine whether the bacteria are motile or not. For this particular technique, we used a special kind of slide; depression slide by covering around of the hollow with Vaseline and prevent escape of bacteria with their flagellar motion. It provides three dimensional spaces for cell movement. Bacillus cereus was observed using this method it is rode shaped motile bacteria that can move by making use of its flagella. We expected so observe the movement and we did.
However, the movement is not very clearly observed since this technique is usually performed without the addition of any stains; therefore, we could not see properly. References How to Set Up a Temporary Wet Mount Slide, eHow. com, Retrived from: http://www. ehow. com/how_8500273_set-temporary-wet-mount-slide. html#ixzz2BicPc4hh http://www. mansfield. ohio-state. edu/~sabedon/black03. htm http://www. personal. psu. edu/faculty/k/h/khb4/enve301/301labs/Lab2_Simple_staining. html