Lab report from Soo Teng

Name : Chai Soo Teng
Matric No. : 111356
Lab 1: Principles and use of microscope
1.1 Setting up and using the microscope

Introduction: In order to be seen,microorganisms need to be magnified. Despite advances in                   other area of microscopy ,the light microscope is still the instrument most frequently used for viewing microorganisms.

Objective:    Learn to use a simple bright-field microscope correctly

Result:

i)                    Typical bacillus (40X magnification)

      ii)Typical bacillus (100X magnification)

iii) Typical bacillus (400X magnification)

Discussion:

1)      To observe the specimen,we begin with the low objective lens power which is 4x objective  ,followed by 10x objective and 40x objective.

2)      The total magnification of the image is calculated by multiplying the objective lens power by the eyepiece lens power.The microscope we use is 10x eyepiece.Thus,the magnification wecan get are 40x magnification,100x magnification and 400x magnification.

3)      We can seen  the colony morphology of Typical bacillus under the microscope.

     

4)      The colony morphology of Typical Bacillus:

Shape:rod-shape

Colour:red

Size:punctiform

Surface:smooth and shiny

Conclusion:The higher the magnification,the clearer the image of the                                                             specimen. Therefore ,we can get the clearly colony morphology of the Typical Bacillus under a high magnification.

References:

http://en.wikipedia.org/wiki/Bacterial_cellular_morphologies

1.2 Examination of cells


Introduction: Because of their extreme minuteness, bacteria are not generally studied with  the low-power or high power-power dry objectives. Instead they are stained   and observed with the oil immersion objective.
 The wet mount methods enables you to study the sizes and shapes of living   microorganisms (drying or staining microorganism distort them). It also enables you to determine if cells are motile. The wet mount method is quick  and easy, and does not require special equipment.

Objectives:  To provide an experience in the use of microscope.

         To illustrate the diversity of cells and microorganisms.

Results

100x objective lens x 10x eyepiece lens = 1000x magnification (with immersion oil)

i)Saccharomyces cerivisiae (yeast) (1000x magnification0

ii)                  Lactobacillus fermentum (1000X magnification)

Discussion:

1)      When we observe the specimen under 1000x magnification,we are using the oil      immersion lens.

2)      Oil immersion objectives are used only at very large magnifications that require high resolving power.

3)      Oil immersion can generally only be used on rigidly mounted specimens otherwise the surface tension of the oil can move the coverslip and so move the sample underneath.

4)      Two different types of microorganisms are observed by using immersion oil:
    -  Saccharomyces cerivisiae (yeast)
    -  Lactobacillus fermentum

5)      Colony morphology of  Saccharomyces cerivisiae (yeast):
    Shape: oval
    Size: tiny
    Surface: smooth and glistening
    Texture: moist
    Color: tannish cream

6)       Colony morphology of  Lactobacillus fermentum:
    Shape: rod 
    Size: punctiform
    Surface: smooth
    Texture: moist
    Color: grey

Conclusion: Oil immersion increase the resolution of a microscope.Under the oil immersion  lens with 1000x magnification,we can clearly seen the colony morphology  and   the  movement of the Saccharomyces cerivisiae (yeast) and Lactobacillus  fermentum.

References:

http://en.wikipedia.org/wiki/Lactobacillus_fermentum

http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae

http://en.wikipedia.org/wiki/Oil_immersion

P.F.Cannon and P.M.Kirk(2007)Saccharomycetaceae G.Winter1881 in Fungal Families of the World:320-321

Gerard J.Tortora,Berdell R.Funke,Christine L.Case (1992)Fungi,Algae,Protozoans,and Multicellular Parasites in Microbiology :298-299