Laboratory Investigations in Microbiology
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Laboratory Investigations in Microbiology |
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Although many of our experiments are carefully pre-planned with a set protocol, every scientific experiment is based on a few underlying premises. Designing a research project intelligently requires you to identify these premises and to put the experiment in context, applying what we see in the laboratory to the real world. These guidelines are meant to help you on the way to writing a good solid research proposal - not merely reporting isolated facts, but interpreting and reflecting on the results.
Your written proposal will be modeled after the writing style of published scientific papers. See here for an example. We will omit the abstract, but keep the rest of the format. Your report will thus have 4 sections, plus a title page and a bibliography.
The Introduction. Scientific investigations usually begin with observations about a phenomenon or process and a question that arises out of these observations. The question that is asked can be as simple as "Does Bacillus subtilis break down cellulose?" or as complex as "What are the regulatory mechanisms by which E. coli regulates the synthesis of the enzyme beta-galactosidase?" However, behind every scientific test or experiment there is a question to be answered. Once the question is posed, the next logical step is to find out as much information as possible about the issue. This is called background information. In the case of starch hydrolysis, this would include information about the structure of starch, the process of hydrolysis, the enzyme(s) needed, the bacteria themselves, and the environment that the bacteria lives in. Collect as much information as you can find in your lab manual, text book and other places and make notes on a sheet of paper. Now, armed with this wealth of knowledge, you can begin making predictions about your problem that you are investigating. Such a prediction is called an educated guess (a hypothesis) because it is based on prior knowledge. Be sure that your hypothesis is supported by what you have written in the background section. For example, you might predict that Bacillus, which lives in soils, should have the enzyme amylase to break down starch. This prediction may be based also on what is known or published about Bacillus - that Bacillus is amylase-positive.
Materials and Methods. Examine the writing style of the materials and methods section in this reference. Notice that the methods are written in the past tense and the passive voice. The materials and methods section should be written in such a way that someone else in your class could repeat the experiment exactly the way you did it just from your description. It is sufficient to mention the precise names of your materials within the text of your methods section (e.g. starch agar plate, Gram's iodine) - you do not have to spell out each ingredient since you did not prepare the medium yourself! Note also that the materials and methods are written in paragraph form. A list of materials is not necessary and should be avoided. WRITE THIS SECTION AS IF YOU HAD ALREADY PERFORMED THE EXPERIMENT
Results. This section of the paper reports all the observations from the experiment. This may include measurements (e.g. absorbance), graphs, tables, photos, descriptions, calculations, etc. Note that the data is described in paragraph form. Figures and tables are used to illustrate the findings, but all important results must be described in written form outside of the figures & tables! Pay attention also to how figures and tables are identified/labeled. Tables are numbered 1, 2, 3... and include a heading above the table. Figures are also numbered sequentially (1, 2, 3...) and include a heading and description below the figure. SINCE WE WILL NOT BE ABLE TO COLLECT MUCH DATA, INCLUDE IN THIS SECTION THE (BLANK) TABLES AND WHAT PICTURES/FIGURES WOULD BE INCLUDED IF YOUR PROJECT WAS COMPLETED.
Discussion. All good things must come to an end, and so, at this stage of the lab report, you need to wrap things up. Re-state the important results of the experiment. Evaluate your hypothesis - do the data support it? How? If not, why not? Also, extend your discussion by speculating on what the significance of these findings is to the bacteria, to us, to the environment etc. WHAT OBSERVATIONS WOULD BE NECESSARY TO SUPPORT YOUR HYPOTHESIS?
© 2003 - 2019 José de Ondarza, Ph.D.