The Effects of Gamma Radiation on Microbial Life. Nolan Jacob 9 th Grade Central Catholic High School

Transcription

1 The Effects of Gamma Radiation on Microbial Life Nolan Jacob 9 th Grade Central Catholic High School

2 Gamma Radiation Produce extremely high frequency radiation Used in the food industry to control the growth of fungi and viruses that cause food to spoil Sterilization of medical instruments

3 Electromagnetic Spectrum

4 What is a linear accelerator? Radiation source used to treat cancer patients Focuses radiation on a small area

5 Escherichia Coli A rod-shaped bacteria Commonly found in the lower intestine of warm-blooded animals Most E. coli strains are harmless Can be grown and cultured easily and inexpensively in a laboratory setting Intensively investigated for over 60 years

6 Purpose The purpose of this experiment is to determine if gamma radiation has an effect on microbial life.

7 Hypothesis Null Hypothesis: Gamma Radiation will have no significant effect on the bacteria Alternate Hypothesis: gamma radiation will have a significant, negative effect on bacterial growth.

8 Materials LB agar plates LB media (0.5% yeast extract, 1% tryptone, 1% sodium chloride) Sterile pipette tips Micropipettes Escherichia Coli Sterile spreader bars Ethanol Incubator Sterile Dilution Fluid (SDF) (22mM Kh2O4, 100nM K2HPO4, 10mM MgSO4, 10nM MgSO4, 1mM NaCl Sterile test tubes Bunsen Burner Vortex Klett spectrophotometer A linear accelerator

9 Procedure 1. Bacteria (E. coli) were grown overnight in sterile LB media 2. Samples o the overnight cultures were added to fresh media in a sterile sidearm flask 3. Cultures were placed in an incubator (37 C) until a density off 50 Klett spectrophotometer unites was reached. This represents a cell density of approximately 10ᶺ8 cells/ml 4. The cultures were diluted in sterile fluid to a concentration of approximately 10ᶺ3 cells/ml µl was transferred into each plate and spread out 6. The proper doses of radiation were given to the bacteria 7. The plates were kept in an incubator for 24 hours, and the resulting colonies counted. Each colony is assumed to have arisen from one cell.

10 Gamma Radiation Effect on Colony Growth Number of Colonies Doses of Radiation(Gy)

11 Number of Colonies Gamma Radiation Effect on Colony Growth P-value= 1.69E Control Doses(Gy)

12 Dunnett s Test T-crit= 3.49 Doses of Radiation T-value Significantor Insignificant 25 Gy 1.24 Insignificant 50 Gy 1.74 Insignificant 100 Gy 3.07 Insignificant 150 Gy 4.97 Significant 200 Gy 4.91 Significant 500 Gy Significant

13 Conclusions The null hypothesis can be rejected The LD50 is about 250 Gy The t-values show that the 25, 50, and 100 Gy did not show a prominent enough difference 150, 200, and 500 Gy did have a large difference from the control

14 Limitations The plates were not all radiated at the same time The doses used were very high and so there was some variation of how much radiation was delivered The plates were transported through cold weather after being radiated Spread plating was slightly unsynchonized

15 Future Experimentations Test other species of bacteria Test mammalian and plant cells Test other sources of radiation such as X-Rays Wider range of exposures Remediation effects?

16 Citations "Gamma Irradiation in the Control of Pathogenic Bacteria in Refrigerated Ground Chicken Meat." Gamma Irradiation in the Control of Pathogenic Bacteria in Refrigerated Ground Chicken Meat. N.p., n.d. Web. 30 Nov "Effects of Gamma Irradiation on Bacterial Microflora Associated with Human Amniotic Membrane." Effects of Gamma Irradiation on Bacterial Microflora Associated with Human Amniotic Membrane. N.p., n.d. Web. 30 Nov Aquino, Ktia Aparecida Da Silva. "Sterilization by Gamma Irradiation." Gamma Radiation (2012): n. pag. Web "Maintaining and Preparing Cultures of Bacteria and Yeasts." Maintaining and Preparing Cultures of Bacteria and Yeasts. N.p., n.d. Web. 30 Nov "Bacterial Cell Culture." OpenWetWare RSS. N.p., n.d. Web. 30 Nov

17 ANOVA SUMMARY Groups Count Sum Average Va ri ance Column Column Column Column Column Column Column ANOVA Source of Variation SS df MS F P-value F crit Between Groups E Within Groups Total

18 Plate Plate Plate Plate Plate Plate