A light microscope (LM) is an instrument that uses visible light and magnifying lenses to verify small objects that are not visible to the naked eyes or in finer detail than the naked eye allows. A light microscope uses two or more lenses to magnify the specimen and it have two sets of lenses which is stage and ocular (Bregman, 1983). Specimens are magnified by the objective lens which is magnified 100 times. The specimen is illuminated by visible light from the light source (the illuminator) that is passed through a condenser, which directs the light rays through the specimen. Resolution (resolving power) is the ability of a microscope to differentiate between two points. The resolution became better if the wavelength of the illumination is …show more content…
A thin film of a microbial suspension, which is called a smear, is spread on the surface of a slide. Flaming the air-dried smear coagulates the microbial proteins and fixes the microorganisms to the slide so they do not wash off. The smear then can be stained. Basic dyes have a colored ion that is positive. It is helping them adhere to bacteria, which are slightly negative. Crystal violet, methylene blue, and safranin are the examples of basic dyes. Acidic dyes are having a negative color ion, are more attracted to the background than to the negatively charged bacteria. Thus, a field of colorless bacteria is presented against a stained background. This is an example of negative staining. An example of an acidic dye is eosin.
Staining is simply means artificial colouring method to facilitate the examination on microorganisms, tissues or other cells under microscope that emphasise certain structure of the cells. There are three type of staining that is simple staining, differential staining and specialized staining.
Simple staining is uncomplicated procedure that involve only one dye. Differentiation of bacteria is impossible. Example for simple staining is positive staining and negative staining.
Second type of staining is differential staining. It involve more than one stain and sometimes with heat fixation. Differential among bacteria
The distance between the target and first focal point (fs) of the standard lens were measured to give χ. The focimeter equation〖[F〗_t= F_(s^2 ) x] was used to work out the correct power of the lenses (Ft). A graph was plotted with Ft being the Y value (in dioptres) and χ being the X variable (in metres). Fs2 remained constant.
Differential media allows for the differentiation between two similar micro-organisms through how the bacteria may handle certain compounds found in the media or the different reactions that may take place when the bacteria is exposed to the medium (3). Selective media on the other hand allow only certain microbes to grow. This is due to the plate containing a limited amount of nutrients, compounds and chemicals that will deter the growth of certain bacteria (3). Dyes, antimicrobial substances, salts, certain growth inhibitors and, antibiotics are also found on this type of medium (3). The differential and selective media mentioned in this lab are as follows:
I expect to learn the biochemical differences in bacteria from this lab. Also, how to identify different species of bacteria. Material & Methods For the first day of the practical, an unknown specimen was provided
Crystal violet was then added for 60 seconds before being washed off with water. The mordant, Gram’s Iodine, was added for another 60 seconds before getting washed off with water. The heat fixed smear was then washed with 95% alcohol until the wash ran clear, leading to the final step of adding Safranin for 45 seconds before being rinsed with water. The slide was finally blot dyed with bibulous paper before it was placed under a microscope to observe the color and shape of the bacterium. 2.2 Litmus Milk Reaction
“ Christian Gram was the one who tried to develop the procedure of Gram staining by attempting to create a way to differentiate stains of schizomycetes from the other tissue cells”(Bartholomew).The Gram-staining was used to determine the morphology of the bacteria by using the cell wall structure. When the bacteria is viewed under a microscope, morphology was seen. Bacteria can have one of the three basic morphologies. The bacteria was cocci, rod, or spirilla morphology. If the result of the bacteria is purple, the bacteria has a thick peptidoglycan layer.
Each plate serves as a first step to identify the unknowns. The TSA (tryptic soy agar) can be used to do a gram stain, which differentiates gram-negatives from gram-positives, based on the structural make up of the cell wall (Carson, 2015). The blood agar plate is used to test for hemolytic activity, which is useful for distinguishing gram-positives. A MacConkey plate is selective by inhibiting the growth of gram-positives and differential due to the fermentation of lactose by certain gram-negative species. In the
DIY - What Is Life? How can you determine whether something is alive, dead, or non-living? Whenever we speak of life, we must think in terms of cells.
Place the slide on the microscope stage. Secure with the sample clips. 7. Focus and centre the specimen using the high objective lens. Adjust focus using the fine focus knob only.
The streaking technique used was a modified streaking for isolation with a heavy quadrant one. The result revealed that bacteria is alpha, with an incomplete breakdown of the medium with a susceptibility of 17mm from the bacitracin gamma hemolysis. That is why the organism represented by the bar graph was in low numbers because it was incomplete. The other test was DNase agar, it is an enzyme test used to identify if the organism has the enzyme DNA. The streaking technique is a single straight line down the middle of the plate.
A dye is a coloured substance that has an affinity, a bond with a physical surface, to the substrate to which it is being applied. Dyes are usually soluble in water. Dyes are used to change the perceived colour of an object. Dyes consist of 2 main parts: chromohore and auxochrome. Before 1856, all dyes were obtained from natural resources.
Background Information: The spectrophotometer is an
From the Unknown tube professor Cooper gave me, I scratched a little on the slant surface with the sterilized inoculating loop. Then I place it on a clean prepared slide which already had a slight drop of water. The two substances are mixed together in the middle of the slide and let dry completely. One extra step of “heat fix” is necessary to adhere everything to the surface of the slide. To start gram staining, I slightly pour crystal-violet all over the slide and let it sit for 30 seconds before wash it off with water.
The ammonia: 1-butanol (1:1) solvent was the appropriate solvent to use for the column chromatography of food dye because it exhibited the properties of a good solvent system. A total 8 colored eluents were collected. The eluents had colors of pink, dark red, dark blue, dark green, light green, yellow, orange and light yellow respectively and
Biochemical tests are the tests used for the identification of bacterial species based on the differences in the biochemical activities of different bacteria. Bacterial physiology differs from one species to the other. These differences in carbohydrate metabolism, protein metabolism, fat metabolism, production of certain enzymes and ability to utilize a particular compound help them to be identified by the biochemical tests. Gram’s stain was originally devised by histologist Hans Christian Gram in 1884. Gram-positive bacteria stain purple, while Gram-negative bacteria stain pink when subjected to Gram staining.
This can be tested by simply mixing the serum of suspected individual which contain the antibodies with the antigens of specific bacteria the accumulation of clumps confirms the presence of particular bacterial infection.[2] This test can be performed in various ways including slide agglutination reaction, tube agglutination reaction, indirect agglutination inhibition reactions etc. Another important practical application involves blood group test of