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Unit 1: Bleach Disnefectant

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Unit 1: Which is the best disinfectant to clean a kitchen surface Chemical or Equipment Micrococcus Luteus Bleach Vinegar Savlon Hazard Biohazard Toxic, Irritant Irritant Harmful Nature of Risk Could make you ill Could kill you Cause irritation Could cause harm Minimise Risk Wash your hands Do not eat Do not drink Wear goggles Do not drink Wash hands Wear goggles Emergency Procedure Seek medical attention Seek medical attention Seek medical attention Seek medical attention Disposal Auto clave Pour down sink Pour down sink Pour down sink Risk Assessment Apparatus Apparatus Reason Cotton swab To place the bacterial culture on the agar plate Agar plate To allow the bacterial culture to grow Beaker To place used swabs containing culture Tweezers To place the paper discs on the agar plate Bacterial culture To see how various disinfectants affect bacterial growth Paper disks To add disinfectants to, to see how they affect bacterial growth Stickers To document where each disinfectant is placed Pen To write on the labels where the disinfectants are Method Collect an agar plate and a culture of Micrococcus Luteus. ...read more.


Vinegar did disinfect to some degree, but not to the extent of bleach, as the mean clear space for this disinfectant was only 21.1 mm. Savlon was the second best disinfectant as it managed to leave a mean clear space of 27.3 mm, which is only slightly less than the bleach which achieved 29.1mm. The three disinfectants work in different ways, which will be described below: * Savlon makes the contents of a cell leak out. This is done by the -OH group of the molecule which bind to proteins which are located on the cell membrane of the bacteria, which disrupts the cell membrane * Bleach attacks the lipids in the cell wall, killing bacteria and micro-organisms. It also destroys the enzymes and structures inside the cell, oxidizing the cell, rendering it harmless * Vinegar is an acid, which bacteria do not grow well in. If vinegar is added to a culture of bacteria, it will limit the growth of the bacterial culture and kill off the bacteria Advanced Method Collect two agar plate and a culture of Micrococcus Luteus. ...read more.


These problems may have affected the results and the integrity of the results. One of the problems occurred was that it was impossible for the bacteria to be spread evenly throughout the agar plate. This problem could easily be solved if bacteria spreaders were used, which guarantee an uniform layer of bacteria throughout the plate. Another problem occurred was that it was difficult to place the paper discs in the centre of each quadrant for each different disinfectant. This, of course, could easily be fixed if a different agar plate had been used for each different disinfectant. Also, a scale could have been placed in the plate, which would have aided the placement of the discs. Some sources of error were also experienced when the examine took place. Some of the bacterial cultures did not grow as much as they should have, or not at all, which may made a disinfectant appear better than it actually was at killing bacteria. Also, it was difficult to measure the clear spaces, due to their irregular shape and the fact it was had use and manoeuvre around an agar plate. ...read more.

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