LAB 4: SOURCES OF CONTAMINATION AND INFECTION

Airborne particles are very fine particles made up of either solid or liquid matter that can stay suspended in the air and spread with the wind. Those microorganisms are major cause of respiratory ailments of humans, can cause allergies, asthma and pathogenic infections of the respiratory tract. Airborne spores are also important agents of plant disease, and the means for dissemination of many common saprotrophic fungi. In the experiment, we found out the roles of airborne spores in crop diseases, some of important diseases of humans and the methods used to monitor spore populations in the air.

Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection.

Materials and reagents

Molten nutrient agar

Sterile water

Sterile petri dishes

Sterile clinical swab

Pipette and tips

Procedures

Air:

1.      The molten agar was poured into sterile petri dish and cool.

2.      The lid was removed from the plate and left it on the side of the plate, faced down. The plates were left for about 5 minutes.

3.      The lids were replaced and incubated at 37oC for 48 hours.

Hands:

1.      The hands were washed by using sterile water without used the soap.

2.      An automatic pipette was used to transfer 1ml of wash water to the petri dish.

3.      Molten nutrient agar was added to the petri dish.

4.      The lids of the petri dish was replaced and the dish was gently rotated until the wash water was thoroughly mixed with the molten agar. The agar did not allowed to contact with the lid of the dish.

5.      After the agar had set, the dish was inverted and incubated 37oC for 48 hours.

Ear:

4.      Molten agar was poured into sterile petri dish and cooled.

5.      A sterile swab moistened with sterile isotonic solution was rubbed into the ear of the subject.

6.      The swab was used to inoculate the labelled plate.

7.      Incubated at 37oC for 48 hours.

Normal breathing:

1.      Molten agar was poured into sterile petri dish and cooled.

2.      The lid was removed and the plate was held about 15 cm from the mouth. Breathe normally but directly onto the plate for one minute. Lid was replaced back onto the petri dish.

3.      Incubated at 37oC for 48 hours.

Violent coughing:

1.      Molten agar was poured into sterile petri dish and cooled.

2.      Lid was removed and plate was held about 15 cm from the mouth. Cough violently onto the agar. Lid was replaced.

3.      Incubated 37oC for 48 hours.

RESULT

Violent coughing

Hands

Ears

Air

Normal Breathing

DISCCUSSION

Different type of method will produce different type of bacteria which will cause the different looking colonies.

HANDS

Hands are part of our body that have the most contact to the outside. Hence it is extremely easy contact with microbes and transfer it to the hands. Microbes also may underneath the fingernails.

For example, hands may contain bacteria such as pseudomonas and Serrantia, fungus such as aspergillus and Cladosporium, yeast such as Candida and Rhodotorula.

EAR

Ear is comprised by 3 compartments:  outer, middle and inner. Because the ear is exposed to the outside environment, it also easy come contact with microbes.

Microbes that are known to at middle ear are Streptococci and most commonly Microbacterium.

Air

The bacteria in the air has direct relation to the amount of the dust. In fact, there are many bacteria are attached to the dust particles.

For example, Staphylococcus and staphylococcus epidermis.

Breathing

During breathing, we inhale the air that may contain varies kind of microbes.

For example, Cyanobacteria and Escherichia coli.

Coughing

Coughing is a repetitively reflex action that help to clear our breathing passages from secretion or microbes. Actually, microbes during breathing and coughing are similar, such as Cyanobacteria and Escherichia coli.

Conclusion

For the experiment above, we can state that there are many kind of bacteria from our part of body.

Reference

http://www.caes.uga.edu/departments/fst/extension/documents/FoodHandsBacteria-UGA.pdf

https://microbewiki.kenyon.edu/index.php/Ear

http://www.booksupstairs.com/Preventive-Medicine-and-Hygiene/Bacteria-in-the-Air.html

http://www.microbeworld.org/types-of-microbes/bacteria

LAB 3: PREPARATION AND STERILIZATION OF CULTURE MEDIA

In study of microorganisms, we need to know how the technique to isolate cells from natural sources and growing them in the laboratory on synthetic media. Thus, development of synthetic culture media is played important roles in this field. Microbes require nutrients to grow. These are supplied by either solid or liquid culture media. Solid media is used for the isolation of bacteria as pure culture. ‘Agar’ is most commonly used to prepare solid media. Agar is polysaccharide extract obtained from seaweed.

The broth contains:

1.5g/L “Lab-lemco” powder (a beef extract)

1.5 g/L yeast extract

5.0 g/L peptone (a nitrogen source)

5.0 g/L sodium chloride

15 g/L agar powder

An autoclave is a pressure chamber used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C (249°F) for around 15-20 minutes depending on the size of the load and the contents. Sterilization is the removal all microorganisms and other pathogens from an object of surface by treating it with chemicals or subjecting it to high heat or radiation.

Materials

Commercial nutrient agar

Balance

Distilled water

Scott bottles

Procedure:

400 ml Nutrient Agar

1.      The 5.0 g/L of peptone, 1.5 g/L of beef extract, 5.0 g/L of NaCI₂, 1.5 g/L of yeast extract and 15.0 g/L of agar were weighed.

2.      The peptone, beef extract, NaCI₂, yeast extract and agar were poured into a beaker.

3.      The 400 ml of distilled water was measured by using measuring cylinder.

4.      The 400 ml of distilled water was then poured into the beaker containing the peptone, beef extract, NaCI₂, yeast extract and agar.

5.      The mixture was stirred evenly until it was dissolved completely.

6.      The solution was poured into Scott bottles.

7.      The Scott bottles were labelled.

8.      The Scott bottles were recapped loosely and were set aside for autoclaving at 121°C for 15 minutes.

9.      After autoclaving, the media was removed. The broth preparation was cooled. The cap of each bottle was tighten.

400 ml Nutrient Broth Agar (self made)

1.      11g of commercial nutrient agar and 6g of agar were weighed.

2.      The broth (with agar) powder was poured into a beaker.

3.      The 400ml of distilled water was measured by using measuring cylinder.

4.      The 400ml of distilled water was then poured into the beaker containing the broth powder.

5.      The mixture was stirred evenly until the broth powder was dissolved completely.

6.      The solution was poured into Scott bottles.

7.      The Scott bottles were labeled.

8.      The Scott bottles were recapped loosely and was set aside for autoclaving at 121°C for 15 minutes.

9.      After autoclaving, the media was removed. The broth preparation was cooled. The cap of each bottle was tighten.

Brain Heart Infusion Agar (BHI)

1.      5.2000g of Brain Heart Infusion Agar was weighed.

2.      The broth powder was poured into beaker.

3.      The 100ml of distilled water was measured by using measuring cylinder.

4.      The 100ml of distilled water was then poured into the beaker containing the broth powder.

5.      The mixture was stirred evenly until the broth powder was dissolved completely.

6.      The solution was poured into a 100ml Scott bottle.

7.      The Scott bottle was labelled.

8.      The Scott bottle was recapped loosely and was set aside for autoclaving at 121°C for 15 minutes.

9.      After autoclaving, the media was removed. The broth preparation was cooled. The cap of each bottle was tighten.

Trypticase Soy Agar (TSAYE)

1.      4.0000g of Trypticase Soy Agar (TSAYE) was weighed.

2.      The broth powder was poured into beaker.

3.      The 100ml of distilled water was measured by using measuring cylinder.

4.      The 100ml of distilled water was then poured into the beaker containing the broth powder.

5.      The mixture was stirred evenly until the broth powder was dissolved completely.

6.      The solution was poured into a 100ml Scott bottle.

7.      The Scott bottle was labelled.

8.      The Scott bottle was recapped loosely and was set aside for autoclaving at 121°C for 15 minutes.

9.      After autoclaving, the media was removed. The broth preparation was cooled. The cap of each bottle was tighten.

 RESULT

1. We were asked to prepare 4 type of culture media.

2. Data of amount of broth dissolved in certain volume of distilled water is tabulated.

For 400ml self-made agar

1.5g of beef extract + 1.5g of yeast extract + 5.0g of peptone + 5.0g of sodium chloride + 15.0g of agar powder + 400ml of distilled water

For 400 ml commercial agar

11.2g commercial nutrient agar powder + 400 ml of distilled water

For 100 ml BHI

5.2g BHI + 100ml of distilled water

For 100ml TSAYE

4.0g TSAYE + 100ml of distilled water

DISCUSSION

1.      Before using the pan and the balance, the balance should be cleaned and the reading should become zero before the powders are weighed.

2.      The media which poured into the Scott bottled have to be stirred to make sure all the powder dissolved inside the distilled water.

3.      The cap of Scott bottle should recapped loosely to prevent it breaking.

4.      For an effective sterilization, the autoclave must not be overcrowded.

CONCLUSION

Autoclave process is a process that effective in conducting the sterilization process. With correct way of autoclave process, preparation of nutrient agar for culturing the microorganisms can be done.

REFERENCE

http://zkfaabioproses10.blogspot.my/2011/03/lab-3-preparation-and-sterilization-of.html

http://www.veinst.hr/en/organisation/branches/vzv/laboratory-for-culture-media-preparation-and-sterilization

http://www.cabri.org/guidelines/micro-organisms/M203Ap1.html