Lab Report Essay

4246 Words Oct 25th, 2012 17 Pages
Kimmi Dodia- Biomedical Science- 1019971

Lab partner- Kim Harcourt

Lab report- Experiment 1: Microbial Genetics
Abstract
The objective of this experiment was to introduce the study of bacterial genetics in order to identify the potency of different mutagenic agents. Our primary aim was to demonstrate the different techniques needed to isolate biosynthetic auxotrophic mutants using chemical, physical and transposon mutagenesis. The second aim was to plan and execute an experiment designed to isolate catabolic mutants (Lac-) as well as conditional mutants (Temperature sensitive) using only a chemical treatment (EMS). Also, to make and characterize transposon-insertion mutants of KL14 using bacteriophage as a transposon delivery
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We followed the protocol as described in page 14-17 of the lab manual. However even though mutagenesis was achieved through EMS treatment, we would have to screen 100-1000 plates to isolate one mutant, therefore in part II of the experiment penicillin enrichment was used. We calculated that 10 µg of ampicillin would be added to the culture of mutagenised cells. The rest of the experiment was conducted as stated in the lab manual following part III onwards to part VIII, we screened for any biosynthetic auxotrophic mutants, picked cells from the mutant colonies, created pure mutant cultures and finally we identified the specific nutritional requirement of each of the mutants we obtained. When starting pure mutant colonies, we ensured that mutant colonies were firstly streaked onto a minimal medium and then a NA plate, this was so no additional nutrient was transferred onto the selective media when streaking the mutant onto two plates, otherwise the biosynthetic auxotroph would have grown on both plates. The second part of this experiment utilized UV light as the physical mutagenesis treatment on the cell culture. The duration that the cells were exposed for played a key role in determining the 99.9% killing of the cells. From analyzing each serial-dilution of the corresponding time-sample onto NA plates, we were able to identify 99.9% killing as a 1000-fold reduction in the cell

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