Lab 1: Yasmin Syafikah Bt Razali

INTRODUCTION

         Because of their extreme minuteness, bacteria are not generally studied with the low power or high 

power dry objectives. Instead they are stained and observed with the oil immersion objective.

         The wet mount method enables you to study the sizes and shapes of living microorganisms. It is 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

RESULT

1. Typical bacillus

100x magnification

400x magnification

40x magnification

2.  Lactobacillus fermentum

1000x magnification

400x magnification

3. Sacchamnyces arerisiae

1000x magnification

400x magnification

DISCUSSIONS

1. Stained cells

             From the observation of Typical bacillus we can classify it as the Gram positive bacteria. It is rod-shaped and has a thick cell wall made of peptidoglycan. It traps crystal violet in the cytoplasm and gives purple-black colour. The alcohol rinse does not remove the crystal violet, which masks the added red safranin dye.

    

            Bacteria cell walls contain peptidoglycan, a network of modified-sugar polymers cross-linked by short polypeptides. Gram-positive rods which often chain. Also, Bacillus spp. are catalase-positive, while Lactobacilli are not. Rod-shaped bacteria which form endospores, with two main division which is the anaerobic spore-forming bacteria of the genus Clostridium and the aerobic or facultatively anerobic spore-forming bacteria of the genus Bacillus. Use different magnification to observe the bacteria under microscope to get the clear view, which is 40x,100x, and 400x magnification.

 2.   Wet mount

                Wet mount helps to study the sizes and shapes of living microorganisms. In wet mount, the specimen suspended in drop of liquid located between slide and cover glass. Immersion oil is usually placed on top of glass cover. in this case the specimen does not get into contact with oil. It is also possible to submerge the specimen in the oil. The oil immersion objective is then rotate directly into the oil observation. By using it, it is a quick preparation and it is possible to observe living and moving organisms using different magnification which is 40x,100x,400x and 1000x magnification. When we use 1000x magnification, we need to use immersion oil, which is to get finer resolution and brightness. It can give clearer image. This characteristics are most critical under higher magnification.

              

                    Aseptic technique is used in this experiment by slow the heat the inoculating wire until it glow orange. Then cool it before attempting any bacteria. Heat the mouth of opening bottle to make sure the microorganisms contamination. 

                     Advantage of using wet mount is quick preparation, few artifacts, living and moving microorganisms and having natural colour. Disadvantages of using it are difficult to take a picture because of movement, evaporation, focus and wet mount cannot be stored over a long time.

   

                     Thus, in this experiment we observe Lactobacillus fermentum under 400x and 1000x magnification. The rod-shaped structure is observed and is moving. Gram-positive bacilli classified in the large family Lactobacillaceae. Often they are found as long, slender Gram-positive rods in long chains. Usually they are contaminating commensals that are readily recognized from colony morphology. Lactobacillus fermentum cannot be seen under 4x and 100x magnification because it is too tiny to be observe under that magnification. Yeast also need to be observe under 400x and 1000x magnification. Yeast does not contain chlorophyll. Shape of yeast is cocci or spherical. 

CONCLUSION 

                     The Gram stain is one of the most useful staining procedure in microbiology. It is one of the three differential staning technique, is used to identify divide bacteria into two groups, Gram-positive bacteria ang Gram-negative bacteria. These staining reaction take advantages of the facts that the cells or structure within the cell display dissimilar staining reactions that can be distinguished by the used of different dyes. A gram positive bacteria can be identified by retaining a purple colour dye within its peptidoglycan exterior. This staining technique is used to help identify various bacteria. The gram positive bacteria that are purple hold stain due to it's layered cell membrane. It contain a peptidoglycan layer acts as a lattice trapping the crystal violet-iodine dye complex. Typical bacillus has a rod-shaped and the average bacillus is 0.5-1.0 um wide by 1.0-4.0 um long. The family Bacillaceae are all gram positive. Rod-shaped bacteria which form endospore, with two main division:

•  the anaerobic spore-forming bacteria of the genus Clostridium
• the aerobic or facultatively anaerobic spore-forming bacteria of the genus Bacillus  

                    Some sample can be placed directly under microscope. However, many sample look better when use immersion oil. This is known as a wet mount. Oil helps support the sample and it fills the space between the cover slip and the slide allowing light to pass easily through the slide, the sample and cover slip. It has been found that some strain for Lactobacillus fermentum have natural resistances to certain antibiotics and chemotherapeutics. They are considered potential vectors of antibiotic resistance genes fro the environment to humans or animals to human.Lactobacillus fermentum can also be a normal inhabitant of human intestinal tract and some strain have been associated with cholesterol metabolism. Lactobacillus fermentum has been identified as potential probiotic. The use of gut microbes as probiotics in food is aim towards preventing and treating various health disease. We also use wet mount method to see yeast clearly under microscope using 400x and 1000x magnification.

REFERENCES 

1.  Pearson international Biology, 8th Edition, Campbell, Reece   


2.http://wiki.answers.com/Q/What_is_the_conclusion_of_a_gram- 
 stain_field_of_red_rods_and_purple_cocci_through_a_microscope

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