1887

Laboratory Activity to Teach about the Proliferation of in Vegetables

    Authors: Massimiliano Marvasi1,*, Manika Choudhury1, Max Teplitski2
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    Affiliations: 1: Department of Natural Sciences, School of Science and Technology, Middlesex University, London, UK; 2: Soil and Water Science Department, University of Florida, Gainesville, FL, USA
    AUTHOR AND ARTICLE INFORMATION AUTHOR AND ARTICLE INFORMATION
    • Supplemental materials available at http://jmbe.asm.org
    • *Corresponding author. Mailing address: Department of Natural Sciences, School of Science and Technology, Middlesex University, The Burroughs, London NW4 4BT, UK. Phone: +44 020 8411 4902. E-mail: m.marvasi@mdx.ac.uk.
    • ©2015 Author(s). Published by the American Society for Microbiology.
    Source: J. Microbiol. Biol. Educ. December 2015 vol. 16 no. 2 230-236. doi:10.1128/jmbe.v16i2.948
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    Abstract:

    We designed a three-week laboratory experience that can complement any microbiology teaching laboratory to expand students’ knowledge of the ecology of human enteric pathogens outside of their animal hosts. Through their participation in this laboratory activity, students learned that vegetative and reproductive plant parts could be a natural habitat for enteric bacteria such as non-typhoidal strains of . This field was recently brought to the forefront of the scientific community and public interest by outbreaks of human illness linked to the consumption of fresh fruits and vegetables. Students were encouraged to develop their own testable hypotheses to compare proliferation of sv Typhimurium LT2 in different vegetables: cherry and regular-size tomatoes, onions, lettuce, and yellow and red bell peppers ( can be substituted for BSL1 laboratories). Upon completion of the laboratory experience, students were able to: 1) Develop testable hypotheses addressing the ability of a human pathogen, , to colonize and proliferate in vegetables; 2) Determine that different vegetables support the growth of to different extents; 3) Conduct statistical analysis and identify any significant differences. The teaching-learning process was assessed with a pre-/posttest, with an average increase in content understanding from ~15% to 85%. We also measured students’ proficiency while conducting specific technical tasks, revealing no major difficulties while conducting the experiments. Students indicated satisfaction with the organization and content of the practices. All of the students (100%) agreed that the exercises improved their knowledge of this subject.

References & Citations

1. Brandl MT 2006 Fitness of human enteric pathogens on plants and implications for food safety Ann Rev Phytopathol 44 367 392 10.1146/annurev.phyto.44.070505.143359 http://dx.doi.org/10.1146/annurev.phyto.44.070505.143359
2. Brandl MT, Cox CE, Teplitski M 2013 Salmonella interactions with plants and their associated microbiota Phytopathology 103 316 325 10.1094/PHYTO-11-12-0295-RVW 23506360 http://dx.doi.org/10.1094/PHYTO-11-12-0295-RVW
3. Cooley MB, Miller WG, Mandrell RE 2003 Colonization of Arabidopsis thaliana with Salmonella enterica and enterohemorrhagic Escherichia coli O157:H7 and competition by Enterobacter asburiae Appl Environ Microbiol 69 4915 4926 10.1128/AEM.69.8.4915-4926.2003 12902287 169118 http://dx.doi.org/10.1128/AEM.69.8.4915-4926.2003
4. Emmert E 2013 Biosafety guidelines for handling microorganisms in the teaching laboratory: development and rationale J Microbiol Biol Educ 14 78 83 10.1128/jmbe.v14i1.531 23858356 3706168 http://dx.doi.org/10.1128/jmbe.v14i1.531
5. Han S, Micallef SA 2013 Salmonella Newport and Typhimurium colonization of fruit differs from leaves in various tomato cultivars J Food Prot 11 1844 2003
6. Islam M, Morgan J, Doyle MP, Phatak SC, Millner P, Jiang X 2004 Fate of Salmonella enterica serovar Typhimurium on carrots and radishes grown in fields treated with contaminated manure composts or irrigation water Appl Environ Microbiol 70 2497 2502 10.1128/AEM.70.4.2497-2502.2004 15066849 383101 http://dx.doi.org/10.1128/AEM.70.4.2497-2502.2004
7. Lynch MF, Tauxe RV, Hedberg CW 2009 The growing burden of foodborne outbreaks due to contaminated fresh produce: risks and opportunities Epidemiol Infect 137 307 315 10.1017/S0950268808001969 19200406 http://dx.doi.org/10.1017/S0950268808001969
8. Marvasi M, George AS, Giurcanu MC, Hochmuth GJ, Noel JT, Teplitski M 2015 Effect of the irrigation regime on the susceptibility of pepper and tomato to post-harvest proliferation of Salmonella enterica Food Microbiol 46 139 144 10.1016/j.fm.2014.07.014 http://dx.doi.org/10.1016/j.fm.2014.07.014
9. Marvasi M, et al 2014 Effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to post-harvest proliferation of Salmonella enterica Food Microbiol 43 20 27 10.1016/j.fm.2014.03.017 24929878 http://dx.doi.org/10.1016/j.fm.2014.03.017
10. Marvasi M, Cox CE, Xu Y, Noel JT, Giovannoni JJ, Teplitski M 2013 Differential regulation of Salmonella Typhimurium genes involved in O-antigen capsule production and their role in persistence within tomato fruit Mol Plant Microbe Interact 26 793 800 10.1094/MPMI-09-12-0208-R 23489058 http://dx.doi.org/10.1094/MPMI-09-12-0208-R
11. Marvasi M, et al 2014 Ethylene signaling affects susceptibility of tomatoes to Salmonella Microb Biotechnol 7 545 555 10.1111/1751-7915.12130 24888884 4265073 http://dx.doi.org/10.1111/1751-7915.12130
12. Marvasi M, Davila-Vazquez YC, Martinez LC 2013 Laboratory activity to effectively teach introductory geomicrobiology concepts to non-geology majors J Microbiol Biol Educ 14 206 212 10.1128/jmbe.v14i2.578 24358384 3867758 http://dx.doi.org/10.1128/jmbe.v14i2.578
13. Newman M, Sundelin T, Nielsen JT, Erbs G 2013 MAMP (Microbe-Associated Molecular Pattern) triggered immunity in plants Frontiers Plant Sci 4 139 10.3389/fpls.2013.00139 http://dx.doi.org/10.3389/fpls.2013.00139
14. Swords WE, Cannon BM, Benjamin WH 1997 Avirulence of LT2 strains of Salmonella Typhimurium results from a defective rpoS gene Infect Immun 65 2451 2453 9169789 175341
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2015-12-01
2017-11-21

Abstract:

We designed a three-week laboratory experience that can complement any microbiology teaching laboratory to expand students’ knowledge of the ecology of human enteric pathogens outside of their animal hosts. Through their participation in this laboratory activity, students learned that vegetative and reproductive plant parts could be a natural habitat for enteric bacteria such as non-typhoidal strains of . This field was recently brought to the forefront of the scientific community and public interest by outbreaks of human illness linked to the consumption of fresh fruits and vegetables. Students were encouraged to develop their own testable hypotheses to compare proliferation of sv Typhimurium LT2 in different vegetables: cherry and regular-size tomatoes, onions, lettuce, and yellow and red bell peppers ( can be substituted for BSL1 laboratories). Upon completion of the laboratory experience, students were able to: 1) Develop testable hypotheses addressing the ability of a human pathogen, , to colonize and proliferate in vegetables; 2) Determine that different vegetables support the growth of to different extents; 3) Conduct statistical analysis and identify any significant differences. The teaching-learning process was assessed with a pre-/posttest, with an average increase in content understanding from ~15% to 85%. We also measured students’ proficiency while conducting specific technical tasks, revealing no major difficulties while conducting the experiments. Students indicated satisfaction with the organization and content of the practices. All of the students (100%) agreed that the exercises improved their knowledge of this subject.

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Figures

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FIGURE 1

Example of workflow of the experiments conducted over the three-week period.

Source: J. Microbiol. Biol. Educ. December 2015 vol. 16 no. 2 230-236. doi:10.1128/jmbe.v16i2.948
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FIGURE 2

Main findings reported after the three-week laboratory experience. Panel A, the yellow arrow shows an example of wound where a 3-μL drop containing was inoculated under the pericarp. Panel B, an example of colonies on XLD. Panel C, final results. Different letters represent significantly different means. Error bars are the standard error. Cherry tomatoes (small sizes) supported less than the larger-size tomatoes. Peppers are the most conducive, and onions are the vegetable with a significantly lower proliferation. XLD = xylose lysine deoxycholate agar.

Source: J. Microbiol. Biol. Educ. December 2015 vol. 16 no. 2 230-236. doi:10.1128/jmbe.v16i2.948
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Image of FIGURE 3

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FIGURE 3

Percent correct answers in the pre- and posttests to assess student learning after the three-week laboratory experience. All the comparisons between the pre- and posttests are significantly different (Student’s -test, = 0.05). Error bars represent the standard error. Please refer to Appendix 4 for the typology of questions.

Source: J. Microbiol. Biol. Educ. December 2015 vol. 16 no. 2 230-236. doi:10.1128/jmbe.v16i2.948
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Image of FIGURE 4

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FIGURE 4

Assessment for student performance. The scale ranges from very good (5), to good (3) to poor (1). Tasks assigned: A) The student is able to properly infect the fruit. B) The student can discriminate colonies on XLD. C) The student can properly plate the XLD plate. D) The student can properly use the stomacher. E) The student is able to pipette properly. XLD = xylose lysine deoxycholate agar.

Source: J. Microbiol. Biol. Educ. December 2015 vol. 16 no. 2 230-236. doi:10.1128/jmbe.v16i2.948
Download as Powerpoint

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