LAB 1 : Principles and Use of Microscope ( Part II )

B. Examination of cells

　　Introduction：

        Bacteria are not generally studied with the low-power or high power-power dry objectives because of their extreme minutes. Instead they are stained and observed with the oil immersion objective.

 　　The wet mount method enables you to study the sizes and shapes of the living microorganisms (drying or straining 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.　

　　Objective：

•          To provide an experience in the use of microscope．
•          To illustrate the diversity of cells and microorganisms．

　　　

　　　Materials and reagents：

• 　Culture
• 　Immersion oil
• 　Lens tissue
• 　Inoculating loop
• 　Bunsen burner
• 　Slide and cover slip

            Procedure: 

1. Bunsen burner is lighted up.
2. One hand is used to sterile the inoculating loop. Then leave it to cool down.
3. Other hand was used to hold the culture. With the same hand replace the culture with slide.
4. Inoculating loop is used to transfer culture into the slide.
5. The inoculating loop is put down and places the edge of cover slip onto the slide and lowered it gently to cover the drop of culture.
6. The slide is placed to the microscope stage and observed by using 4x, 10x, and 40x objective focus on the culture.
7. Immersion oil is applied onto the slide to be observed under 100x magnification.
8. Culture is observed was drawn.
9. This procedure is repeated with other culture.

                 

                 Result : 

             

                 The slide

       Observation :

      Lactobacillus sp. 

  
   From Observer :

Video :

Escherichia coli

From Observer :

Video :

        Discussion :

        Bacteria usually studied with the low-power dry objective. But in order to study their movement, size and shape, the wet mount must be used. This is because technique in preparing wet mount does not kill the bacteria. Simple technique of aseptically is used to transferred the bacteria from medium bottle to glass slide. Then, immersion oil is used at 100x objective lens unless the cell is very small and moving slowly.

The bacteria:

1. Lactobacillus acidophilus

The scientific classification

·         Kingdom : Bacteria

·         Division : Firmicutes

·         Class : Bacilli

·         Order : Lactobacillales

·         Family : Lactobasillaceae

·         Genus : Lactobacillus

·         Species : L.acidophilus

The morphology

·         Shape : rod shape

·         Color : grey

·         Size : 0.6-0.9 μm in width and 1.5-6.0 μm in length

2. Escherichia coli

The scientific classification

·         Kingdom : Bacteria

·         Division : Eubacteria

·         Class : Proteobacteria

·         Order : Enterobacteriales

·         Family : Enterobacteriaceaa

·         Genus : Escherichia

·         Species : E. coli

The morphology

·         Shape : rod shape

·         Color : red

·         Size : approximately 0.5 μm in width by 2 μm in length

References

1.              http://www.microbehunter.com/2010/08/13/making-a-wet-mount-microscope-slide/
2.              http://www.trueart.info/wet_mounting.htm
3.               http://en.wikipedia.org/wiki/Lactobacillus
4.               http://en.wikipedia.org/wiki/Lactobacillus_acidophilus
5.  .            http://en.wikipedia.org/wiki/Escherichia_coli