M. Luteus Lab Report

DISCUSSIONIn the first part of the lab, since the effect of moist heat treatment on bacterial spores wasbeing investigated, the spores from Bacillus stearothermophilus was used. Using the three testtubes with spores, the first one (1) was autoclaved, the second (2) was boiled, and third (3)received no treatment. The fourth test tube (4) didn’t have a spore strip and served as a controlfor the effectiveness of the aseptic pipetting technique. As hypothesized, test tubes 1 and 4experienced no bacterial growth. Because tube 4 had no spore strips, it was predicted that nobacterial growth will be observed; had there been a presence of bacteria, it would mean that therewas some contamination during the pipetting process. It can consequently be said
Marcescens culture. Though there was anexperimental error, the effect of UV light radiation on bacterial cells was observed. Comparingboth plates from another group, it was noted that though both plates were subjected to the sameUV light exposure, the M. luteus experienced more growth; this is because M. luteus has a higherlevel of resistance to UV radiation than S. marcescens. The S. marcescens colony was expectedto turn pink instead of its usual red color because its pigment production can be influenced UVradiation; the longer its exposure to UV, the lighter its pigment becomes. The S. marcescens andM. luteus were used for this experiment because they have different levels of UV resistance.Filtration is a method used to physically remove bacteria, viruses and fungi from culturemedium. In test tube 1, where non-sterile glucose was used, growth was noted, whereas in testtube 2 (sterile glucose), no bacteria growth was noted. This proves that the filtration is asuccessful method of sterilization. Test tube 3, containing only TSB, and Test tube 4, containingsterile glucose without TSB, served as controls, and both experienced no bacterial growth; Forbacteria to grow, it needs to be in a suitable growth medium.T-streaking is a method used to isolate a pure bacterial strain from a co-culture. Asevident from the T-Streaking results, a pure bacteria colony was isolated from the mix culture.The colony isolated resembled a Staphylococcus aureus.CONCLUSIONThe aim of this lab, to identify the most effective sterilization method was achieved.From the first experiment, it was concluded that the autoclaving method of sterilization is veryeffective in sterilizing bacteria and spores, while the boiling method proves ineffective intreating contaminations by spores. Filtration, a method of sterilization, used to extract spores andbacteria from a liquid, was also effective. It was noted from the UV experiment that the longer