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Effect of UV radiation on bacteria
By Tyler Zeik
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Problem Is bacteria growth significantly altered by exposure to UV radiation?
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Escherichia coli (E. Coli)
Some strains aid digestion Live in intestines Pathogenic strains commonly in uncooked meats
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Staphylococcus Aureus (Staph)
Most common cause of food poisoning Commonly found on surface of skin
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Ultraviolet Radiation
3 forms of UV UVB- enough energy to cause photochemical damage to DNA, not enough for ozone to absorb it UVC- rarely encountered by humans because it's absorbed by the ozone UVA- tans you. Wavelength makes it difficult to be absorbed by ozone but it provides Vitamin D
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Hypotheses Null- UV radiation will have no effect on the growth of bacteria Alternate- UV radiation will have a significant effect on bacterial growth
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Materials 105 bacteria ager plates
P200 Micropipette pump and sterile tips UV lamp Bacteria incubator Bacteria cultures Spreader bars Ethanol Matches
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Procedures Sterilize spreader bars with ethanol
Pipette 100 micro-liters of bacteria onto ager plates Spread solution evenly with spreader bars Remove lid and place under UV lamp Apply concentrations of UV and replace lids Let incubate for allotted time Count colonies
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Results # E. Coli Recorded Replicate Number Colonies Surviving
E. Coli P- value X 10-28
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Results # Staph Recorded Blue- 0 Sec Green 2 Sec Yellow- 5 Sec
Colonies Surviving Blue- 0 Sec Green 2 Sec Yellow- 5 Sec Orange- 10 Sec Red- 15 Sec Purple- 20 Sec Light Blue- 30 Sec Staph P-value X 10-21 Replicate Number
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Results # Resistant E. Coli Recorded Replicate Number
Colonies Surviving Radiation Resistant E. Coli X 10-14 Replicate Number
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Yellow- Resistant E. Coli
Results Bacterium Averages Colonies Surviving Yellow- Resistant E. Coli Green- Staph Blue- E. Coli Seconds exposed to UV
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Yellow- Resistant E. Coli
Results % Bacterium Surviving % Colonies Surviving Yellow- Resistant E. Coli Green- Staph Blue- E. Coli Seconds exposed to UV
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Conclusion The UV radiation had a significant effect on the growth of bacteria. The alternate hypothesis is accepted.
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Use more variety of bacterium for more data
Extensions Use more variety of bacterium for more data
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Sources and References
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Raw Data Anova: Two-Factor With Replication SUMMARY 0 sec 2 sec 5 sec
Total set 1 Count 5 35 Sum 1835 1038 388 11 6 9 7 3294 Average 367 207.6 77.6 2.2 1.2 1.8 1.4 Variance 609.5 937.3 5.2 0.7 4.7 6.8 ANOVA Source of Variation SS df MS F P-value F crit Sample 65535 Columns Interaction Within 9308 28 34
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Raw Data cont. STAPH Set 1 Set 2 Set 3 Set 4 Set 5 Average % surviving
0 sec 402 404 362 380 350 2 197 249 247 240 203 227 60 5 190 199 155 164 50 10 117 94 70 58 48 77 20 15 30 29 16 11 19 1 6 12 4 E. COLI 392 377 329 357 367 183 177 223 208 237 209 57 83 129 78 21 0.005 0.003 3 RESISTANT E. COLI 453 420 499 437 456 338 389 348 414 373 0.82 304 369 374 398 282 345 0.76 299 305 278 229 222 267 0.59 225 279 244 250 239 0.53 187 92 130 109 161 136 0.3 95 52 0.11
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