Isolation and identification of individual microbes and growth and monitoring of microbes.

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Assignment 2                Melanie Harris

MICROBIOLOGY


This assignment is divided into two sections, the first deals with the isolation and identification of individual microbes. The second part looks at the growth and monitoring of microbes.

Identification of microbes: A case study

Practical: Aseptic technique

Write a step-by-step guide on how to perform an aseptic technique, include a reason and explanation of the precautions taken.  Make reference to the health and safety legislation covering micro-organisms.

All of these steps are to ensure that cross contamination does not occur and cause the results to be misleading.

  1. Make sure bench is clutter free. So that belongings do not get contaminated / or the sample doesn’t get contaminated.
  2. Hair should be tied back. To avoid contamination or accidents, such as hair catching fire from a Bunsen burner.
  3. Lab coats should be worn. To avoid cross contamination
  4. Bags and coats should be stowed away under the bench or in a cloakroom. To avoid accidents / cross contamination
  5. Wipe bench down with alcohol. To sterilise working area before and after practical
  6. Collect all equipment and set it up. So that you are ready to begin and can work in an organised manner with out the risk of contaminating a clean area.
  7. Keep the lids of the petri dishes closed. So that they do not get contaminated with micro-organisms that are in the atmosphere
  8. Wipe any slides that will be used with alcohol. And place them in on the bench that has been cleaned with the alcohol. So that the are sterile
  9. Heat the inoculation loop in a Bunsen flame until it glows red and is sterilised. This will kill any micro-organisms that are present on the inoculation loop
  10. Sterilise the rim of the receptacle that the micro-organism is stored in, by moving it through a Bunsen flame. To kill any alien micro-organisms that might be present.

Streaking plates:

Starting at a ’12 o’clock’ point dip a sterile inoculating hoop into the sample, then making quick stokes, spread the sample on the media as in the above picture.  Be careful not to keep the petri lid of for to long, or to let your fingers touch the media, as this will introduce alien micro-organisms to the media.

(The government has set out guide lines to the use of micro-organisms, I have included this in the appendices.)

Association for Science Education (from www.ase.org.uk)

Emergency facilities

The location of fire extinguishers, emergency cut-offs, and the teacher should know eye washing facilities and fire exits.

Personal protection

Students, teachers and technicians should wear eye protection whenever the risk assessment for the activity requires it. Other protective or control equipment, such as safety screens or fume cupboards, should be used when required.

Coats and bags

These should be put well out of the way. Students will need frequent reminders. Ideally, there should be coat hooks in a quiet corner of the laboratory, and bags should not be allowed to clutter the floor.

Eating, drinking, chewing and smoking

These should not be permitted in the laboratory. If, exceptionally, a tasting activity is to take place, teachers must stress the special nature of this event and should adopt strategies to ensure that contamination cannot occur. Ideally, a home economics room or dining area should be used.

Hair

Long hair should be tied back and students should be warned that loose, flowing hair could make the hair more venerable to catching alight.

Clothing

Check that students’ clothing is suitable for the activity and does not, for example, present a fire hazard. Ties, scarves and cardigans should not be allowed to hang freely, as they could be a fire hazard or catch in machinery.

Bunsen burners

When they are lit but not being used, Bunsen burners should be adjusted to show the yellow flame. They should be positioned carefully to avoid igniting wall fittings or blinds and so that students are not tempted to lean across them. Students should also be warned against meddling with gas taps.

Containers

Containers should be clearly labeled, with an appropriate name, any hazards identified (for example by a symbol) and the date of acquisition or preparation. Technicians or students sometimes fail to remove old labels, which can be confusing and hence dangerous. When containers are labeled, It is important to remember that the hazards of a solution are likely to be different from those of the substances from which it was made.

Extended practicals

Practical activities extended over a period of time should always be clearly labeled and dated, with any hazards identified. Equipment, which is left, running, should have an appropriate warning notice

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Spills

Spills should always be cleared up immediately. While a few may need absorption and/or chemical neutralization using a spill kit (or disinfection or similar treatment), most minor spills can be dealt with by a damp cloth. For large spills of chemicals producing hazardous fumes, there may be a need to call the fire brigade. Students should be encouraged to report spills and breakages, so that they can be cleared up immediately, and not left to cause injury to the next class, or to a technician or cleaner.

Personal cleanliness

Students should always wash their hands after practical work with ...

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