Correlating Culture Turbidity with Cell count Lab Report

Correlating Culture Turbidity with Cell count Lab Report, consist of:



Methods and Materials ( should feature the “techniques” used to obtain data ).

Results and Discussion together



Check the files and read the instructions carefully for the lab report, and read the experiment manual.

Advanced Microbiology Lab Report

A good lab report has a format that includes five main sections. They are the introduction, methods and materials, results, discussion and conclusion, and citation. (See page 2 for lab report assignment instructions)


The introduction of a lab report states the purpose of your experiment. Your hypothesis should be included in the introduction, as well as a brief statement about how you intend to test your hypothesis.

To be sure that you have a good understanding of your experiment, some educators suggest writing the introduction after you have completed the methods and materials, results, and conclusion sections of your lab report.

Methods and Materials:

This section of your lab report involves producing a written description of the materials used and the methods involved in performing your experiment. You should not just record a list of materials, but indicate when and how they were used during the process of completing your experiment. All past tense – this is a report of what was done, what was used. This is not a recipe were you are telling someone what to do or giving someone instructions on how to do something.

Common lab procedures/techniques do not have to be explained, e.g. removing pipettes from package, how to draw liquid into the pipette, how to spread bacteria on an agar surface, etc.

The information you include should not be overly detailed, but should include enough detail so that someone else could perform the experiment by following your instructions using the usual standard lab techniques and procedures.

Results (or Results and Discussion together):

The results section should include all tabulated data from observations during your experiment. This includes charts, tables, graphs, and any other illustrations of data you have collected. You should also include a written summary of the information in your charts, tables, and/or other illustrations. Any patterns or trends observed in your experiment or indicated in your illustrations should be noted as well.

Discussion (or Results and Discussion together):

This section is where you summarize what happened in your experiment. You will want to fully discuss and interpret the information. What did you learn? What were your results? Was your hypothesis correct, why or why not? Were there any errors? If there is anything about your experiment that you think could be improved upon, provide suggestions for doing so.

Citation: (See Pechenik citation guidelines)

All references used should be included at the end of your lab report. That includes any books, articles, lab manuals, etc. that you used when writing your report.

Example APA citation formats for referencing materials from different sources are listed below (Pechenik).


Name of author or authors (last name, first initial, middle initial)

Year of publication

Title of book

Edition (if more than one)

Place where published (city, state) followed by a colon

Publisher name

For example: Smith, J. B. (2005). Science of Life. 2nd Edition. New York, NY: Thompson Brooks.


Name of author or authors (last name, first initial, middle initial)

Year of publication

Article title

Journal title

Volume followed by issue number (issue number is in parenthesis)

Page numbers

For example: Jones, R. B. & Collins, K. (2002). Creatures of the desert. National Geographic. 101(3), 235-248.

Jones, R. B. and Collins, K. 2002. Creatures of the desert. National Geographic. 101(3), 235-248. J. Bacteriol. 34: 345-56

BIO455 Advanced Microbiology Lab Report Instructions Fall 2017

Correlating Optical Density with Dilution/Cell Concentration

For this lab report use the basic format as detailed on Page 1 (similar to an “American Society for Microbiology” journal article).

See a few examples of ASM or similar journal articles on our BIO455 Bb.

Materials and Methods should feature the “techniques” used to obtain data. Example: For the plate count 1/10 serial dilutions were made using sterile peptone water. (You do not describe how a pipette is used, or how to take a cap off of a test tube). No recipes, report all techniques in the past tense (you are reporting what you did, not giving recipe instructions to someone else).

From your raw data collected in lab, prepare an OD vs. dilution (1/100 up to the undiluted) plot with the proper description and caption. Add an additional “scale” under the dilution axis for the cell concentration (cfu/ml – calculated from the results of the plate count/concentration of the original culture) at each dilution. Graph axes must be labeled. Draw a line through the data points and add the “expected” line to show the deviation from Beer’s Law.

Discussion should include why the actual data line does not continue straight.

From your graph indicate what OD value represents the cell concentration of 8 X 107 cfu/ml.

Include any references, and write an Abstract (limit 200 words) for the report (Abstracts are usually a single paragraph summary of the entire article/report).

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