"Do bacteria survive longer on cutting boards made of wood as opposed to plastic?"
could carry out in a lab or even at home. You will develop the hypothesis, the method (design) for the experiment; a plan on how to collect the data, possible outcomes, and conclusions. In short, you will develop everything that needed for an experiment without actually testing it.
Please take a very close look at the rubric at the end of this document. It will help you to understand how you will be graded and expectations for in this assignment.
Since this is likely to be one of your first experiences in designing experiments that are not simply “cook-book” exercises, I have compiled a list of suggestions and guidelines that should help you to carry out this project successfully. Please read the following guidelines carefully, and spend some time planning your experiment accordingly.
The more focused your investigation is, the more likely you are to be successful in devising clear-cut experiments. For example, if you focus your experiments on answering the question “Do bacteria survive longer on cutting boards made of wood as opposed to plastic?”, you should be able to devise simple experiments that can clearly answer this question “yes” or “no”. On the other hand, if you focus on a more general question such as “How do bacteria survive?”, you will have a more difficult time deciding what experiments to do and how to carry them out.
Ideas for Research Projects
The following list is deliberately vague. I have suggested a number of possible projects, each of which can be varied considerably depending on your interests and ideas. This is by no means a definitive list; you may have other ideas for projects that do not appear here.
Quantitative Experiments. How many bacteria are in ________ (a kitchen sponge? a thoroughly washed hand? road sand? a gram of ground beef? etc.) This is one of the most straightforward, and yet surprisingly interesting, of experimental questions in microbiology. The basic procedures are simple: dilution series and viable count assays. One can modify these assays to even simpler, “semi-quantitative” assays for an initial screening.
Here are some possible applications:
* comparing the number of bacteria in a variety of water samples. This can be extended by looking for the presence of indicator organisms for fecal contamination: E. coli and Enterococcus faecalis .
* comparing the number of bacteria in eggs, meat, poultry, fish, or other foods. Samples are first weighed, then mixed with sufficient water to produce 1% solutions (1 gm/100 ml), and mixed thoroughly in a blender. Dilutions are assayed for total count. It is also possible to screen for the presence of certain pathogens (e.g. Salmonella) or fecal indicator organisms.
* comparing the survival of a pathogenic indicator organism (such as E. coli, an enteric bacterium that has similar survival abilities to pathogenic enterics such as Salmonella) on wood vs. plastic cutting boards. The FDA requires plastic cutting boards in food preparation, arguing that they are easier to clean. However, recent reports suggest that bacteria disappear from wood surfaces much faster.
* examining “microbiology in the home”. Where are bacteria found in greatest abundance? How contaminated is a sponge that is used several times a day to clean food preparation surfaces?
* examining the variation of numbers of bacteria in different habitats. You can investigate the distribution of S. aureus on different parts of the same person.
* examining variation over time. For example, we know that bacterial numbers on hands goes down after hand washing. But how soon does it come back up, and to what extent? A careful study, in which the same skin area was swabbed at different times and then assayed for total count, might be very revealing.
Write a typed, well-constructed (complete sentences, proper grammar / spelling) lab report of your experiment.
- Creativity is encouraged.
Include a reference section (as an additional page) with at least 4 citations including at least one published (journal or textbook) reference.
- Use resources such as microbiology text books, encyclopedias, HCC Library databases (e.g. Pro Quest Biology, Pro Quest Nursing), journals, and online medical sites to research these questions. Indicate the source of information either in ACS or MLA format. Do not forget to include in-text citations every time you borrow someone’s idea, even if you paraphrased it. Be sure to include the publication date.
- Comment on the reliability of the source (why you think this source is reliable … “because it is on the internet” is NOT a good answer) under each reference.
- All references must be cited, and direct quotes from the references must be indicated as such, using quotation marks. However, in science writing, direct quotes are seldom used. Instead, paraphrase the information in the reference, and supply the citation.
- In the case of plagiarism, all students involved will receive a “0” on this assignment. Thereafter, plagiarism will be handled according to the College’s Academic Honesty Policy.
Please submit your individual Theoretical Experiment through CANVAS. The deadline date is on the Canvas calendar online. Your work will be submitted through VeriCite for plagiarism.