Sunday, August 4, 2019
1) In the distribution of microorganisms lab, the largest number of colonies came from a mouth swab giving over 300 small yellow and white, punctiform and convex colonies. Hair came in next with 99 colonies on the plate of all different colors, sizes and shapes. The culture dish that sat out in the lab air gave a total of 15 colonies of all different types. The swab of disinfected bench gave a total of 9 colonies, one of which was very large. The control that was never opened and the swab of disinfected bench ended up having no colonies grown on them. Hair and air are the most realistic contaminants since your hair is openly exposed to the lab at all times and the air comes into contact with the sample whenever the sample is opened. However, the greatest potential source of contamination shown by the number of colonies is the mouth sample (optional source). This was expected because the human mouth is known to contain many bacteria. 2) Even though the 4x level of magnification on the microscope is not used often since it is such a small magnification, it may be used to start focusing the microscope although not much will be visible. The microscope is parfocal meaning Ã¢â¬Å"that the optical system is coordinated so that a specimen that is in focus for one objective is in approximate focus for the other objectivesÃ¢â¬ (Hayden McNeil Publishing, 2014), so once the 4x objective is focused, the other objectives should be coarsely focused. They will require some fine focus adjustment though. The 10x objective helps to increase the focus and will also make the specimen more visible and can be used to find the location of the specimen on the slide (Hayden McNeil Publishing, 2014). This objective is also known as the Ã¢â¬Å"low power objec... ...ed specimens (Hayden McNeil Publishing, 2014). Also, for pathogenic bacteria, once the structure is determined it can be attacked. Ã¢â¬Å"Gram positive bacteria are more susceptible to antibacterial agents that work by inhibiting the formation of peptidoglycan cross-links thereby weakening their cell wallsÃ¢â¬ (Hayden McNeil Publishing, 2014). 4) The species tested for spore formation were Bacillus subtilis and Corynebacterium glutamicum. Bacillus subtilis actually formed spores. The endospores that developed were a stress response to being treated with the toxic dye, malachite green. The bacteria, Bacillus subtilis, will produce endospores as a form of resistance against unfavorable environmental conditions such as toxins and heat. The Corynebacterium glutamicum does not form endospores in response to extreme environmental conditions (Hayden McNeil Publishing, 2014).