COMPARATIVE STERILIZATION OF ESCHERICHIA COLI THE TITLE SHOULD BE SPECIFIC
JONATHAN SO
DEPARTMENT OF BIOLOGICAL SCIENCES
SADDLEBACK COLLEGE
MISSION VIEJO, CA 92692
Because of the danger of pathogenic contamination in food production, medical and
laboratory research it is important to determine if(whether) microwave irradiation or submersion
in 100°C hot water bath is more efficient in regards to inactivation of E. coli. Inoculates of
Escherichia coli were subjected to submersion in 100°C hot water bath heating and microwaves at
2450 MHz for 30s and 60s. Inoculated in 2450MHz for 30 seconds and 60 seconds, samples were…
Samples of the treated inoculates were then streak plated and allowed to incubate for 96 hours after
which colonies were counted, recorded and analyzed via ANOVA. Post Hoc analysis indicated no
statistically significant difference between microwave irradiation at 2450 MHz and submersion in
100°C hot water bath.
INTRODUCTION?
Efficient sterilization of pathogens is of
interest to many fields; the food industry,
medical/hospital, waste and bio-hazard treatment,
because of its relative low cost microwave
irradiation is particularly appealing (Celandroni
et al. 2004; Górny et al. 2007; Latimer and
Matsen 1977). While other studies have focused
on the cellular effects, structural or metabolic of
microwave irradiation compared to those of
conventional heating (Celandroni et al. 2004;
Dreyfuss and Chipley 1980; Woo, Rhee and
Park 2000), the aim of this project is to compare
the efficiency of inactivation of E. coli by
microwave irradiation and by submersion in
100°C water.
MATERIALS AND METHODS
The microwave oven used in the
experiment was a consumer grade Sears
Roebuck,
Model
No.
5678701080
2,450MHz microwave oven manufactured in
1986.retype with efficient spacing E. coli
was used throughout the experiment. Fifty
two glass 13x100mm test tubes containing
5ml of Nutrient Broth were inoculated with
E. coli using as aseptic technique. Inoculates
were then incubated at 37°C for 24hours.
Inoculates were then exposed to
irradiation in the microwave by placing one
test tube at a time in the center of the
microwave oven and irradiating for 30s or
60s, n=10 per interval. Hot water bath
inoculates were subjected to submersion in a
100°C water bath for 30s and 60s.
Microwave irradiated and 100°C water bath
samples were then streak plated on Nutrient
Agar plates, and incubated for 96 hours at
37°C. Colonies produced by/of viable E. coli
on plates were counted and recorded. Data
were then analyzed with ANOVA followed
by Boneferri post hoc correction. Explain
the control.
RESULTS
Microwave irradiation did not result
in a statistically significantly greater
inactivation of E. coli than those treated in
hot water bath. (FIGURES 1, 2 and TABLE 1)
Insert the unit ex. Time(sec)
the paper. Just mention the mean value.
TABLE 1. effect of exposure Effects of exposure upon number of colonies of E. coli produced
30s
Number of colonies
Hot water
0
1
74
82
77
23
40
0
49
150+
bath
Irradiated
0
0
1
0
36
150+ 0
0
0
0
60s
Hot water
64
43
13
0
67
14
18
4
3
0
bath
Irradiated
0
0
0
0
0
0
3
0
0
0
0s
Control
150+ 150+ 150+ 150+ 150+ 150+ 150+ 150+ 150+ 150+
FIGURE 1. effect of exposure on E. coli
Dump the table while you’re at it also.
colonies produced. No raw data should be in
FIGURE 2. Bar graph of Effects of exposure upon mean colonies of E. coli produced In sert the
error bar. Enter the unit. Indicate what HWB and MI are.
DISCUSSION
Though the results of no statistically
significant difference between microwave
irradiation at 2450MHz and submersion in
100°C hot water bath differed from previous
findings by Gee and So (2009),which is? the
overall inactivation at 60s of irradiation
reflected those found by Latimer and Matsen
(1977) . The difference in findings between
this experiment and that of Gee and
So(2008) are most likely attributed to
greater number of intervals ran as well as
different statistical analysis. which is?
LITERATURE CITED
Celadroni F., Giannessi F., Ghelardi E., Longo I.,
Tosoratti N., Baggiani A., Salvetti S.,
and Senesi S. 2004. Effect of microwave
radiation on Bacillus subtilis spores.
Applied and Environmental Microbiology, 97:
1220-1227
Chipley J.R., Dreyfuss M.S. (1980) Comparison
of effects of sublethal microwave
radiation and conventional heating on
the metabolic activity of Staphylococcus
aureus. Applied and Environmental
Microbiology, 39: 13-16
Gee B. and So J. (2009) The Comparative
Efficiency of Sterilization by conventional
Heating And Microwave Irradiation On E.
coli. Saddleback Journal of Biology 7,119
Górny R., Harkawy A., Kasznia-Kocot J., Lis D.,
Łudzeń-Izbińska B., Mainelis G.,
Marzec S., Niesler A., Siwińska E.,
Wlazło A.(2007) Viability of fungal and
Actinomycetal spores after microwave
radiation of building materials. Ann
agric Environ Med 14: 313-324
Latimer J, Matsen M. (1977) Microwave oven
irradiation as a method for bacterial
decontamination
in
a
clinical
microbiology laboratory. J Clinical
Microbiology, 6: 340-342
Park H-D., Rhee I-K, Woo I-S. (2000)
Differential damage in bacterial cells by
microwave radiation on the basis of cell
wall
structure.
Applied
and
Environmental Microbiology, 66: 22432247
Review Form
Department of Biological Sciences
Saddleback College, Mission Viejo, CA 92692
Author (s):___________Jonathan So__________________________
Title: Comparative Sterilization of Escherichia Coli
_________________________________________________
Summary
Summarize the paper succinctly and dispassionately. Do not criticize here, just show that you understood the paper.
Microwave and boiled water was used to compare the sterilization against E. coli. One was placed in hot
water bath of 100ºC for 30 and 60 seconds. The other group was irradiated in a microwave for same
periods of time. After 96 hour of incubation period at 37 ºC, the colonies were counted and compared.
According to statistical analysis ran, there were no significant difference between the two groups in
ability of sterilization against E. coli.
General Comments
Generally explain the paper’s strengths and weaknesses and whether they are serious, or important to our current
state of knowledge.
The hypothesis tested was clear and strong but the result and discussion were weak. Specific values of
means and standard errors should be shown. The discussion should be more specific. Sterilization is very
important and it should state why the two groups were compared and what are the advantages and
disadvantages of the two groups. With more research, the statement could be much more strong and
the research could be very useful.
Technical Criticism
Review technical issues, organization and clarity. Provide a table of typographical errors, grammatical errors, and
minor textual problems. It's not the reviewer's job to copy Edit the paper, mark the manuscript.
This paper was a final version
xThis paper was a rough draft
Samples of the treated inoculates were then streak plated and allowed to incubate for 96 hours
after which colonies were counted, recorded and analyzed via ANOVA. (run on)
Inoculates of Escherichia coli were subjected to submersion(submerge) in 100°C hot water bath
heating and microwaves (microwaved) at 2450 MHz for 30s and 60s.
Fifty two glass 13x100mm test tubes containing 5ml of Nutrient Broth were inoculated with E.
coli using as aseptic technique (a specific technique).