1.43: Unknown Bacteria Identification Project Report

Learning Objectives

• Write an organized and well formatted scientific report detailing the Unknown Identification Project.
• Understand expectations of the Unknown Identification Project Report and grading guidelines.

 

Instructions for Writing Unknown Bacterial Species Identification Project Report

 

Originality

 

TurnItIn

The words in your report must be 100% your own. To make sure that the report is 100% your own, you will submit this report using TurnItIn. TurnItIn compares your report with websites, books, publications, and the work of other students who have submitted their documents to TurnItIn. For your report to be acceptable, the similarity rating between your work and other works will need to be below 20%.

 

Citing Sources

You may use outside resources to provide information that will help you to write the report (e.g. information about Gram stains, oxidase test, starch hydrolysis test, etc.), but you must cite ALL the sources of information you used at the end of each sentence. The text must also be fully in your own words. Do not just change a couple words around. TurnItIn is smarter than this and will flag the text.

 

Example 42.1

Example of scientific writing using information from an external source:

The initial Gram stain was unsuccessful the first time since all of the cells appeared purple, indicating that the decolorization step was too short (Pakpour and Horgan, 2021). As a result, the initial Gram stain was repeated using a decolorization step that was 10 seconds longer than in the previous attempt. This produced a Gram stain where Gram negative rods and Gram positive cocci were apparent.

More Information about this Example

In this example, the authors' last names are Pakpour and Horgan and the work is from 2021. A full reference would then be provided at the end of the report in a "Works Cited" section.

 

Works Cited Section

A works cited section is found at the end of a scientific report. It lists the full references for all external resources cited throughout the entire report. There are many different ways to format a Works Cited section. What matters most is:

• you use the same professional formatting for your references (i.e. consistency)
• references are complete (with title, year, author name(s), publisher/journal/book name, URL (if applicable), page numbers/name (if applicable), etc.)
• references are listed in alphabetical order
• use at least three (3) different reputable sources (try adding "NCBI," "ASM," or "CDC" to a Google search to obtain some quality sources).

Example 42.2

Works Cited

Hartline, 2022. Starch Hydrolysis. Microbiology Laboratory Manual. LibreText. Accessed on 10/30/2022 from:

Pakpour and Horgan, 2021. Lab 3: Simple, Negative, and Gram Stain. General Microbiology Lab Manual (Pakpour & Horgan). LibreText. Accessed on

10/29/2022 from: https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Book%3A_General_Microbiology_Lab_ Manual_(Pakpour_and_Horgan)/Lab_03%3A_Simple_Negative_and_Gram_Stain

 

Quoting Sources

Quoting another author in the sciences is rare. As a result, in this report, quoting another author is not allowed. Take information from texts and put it into your own words and cite the source. Don't just change one or two words (Turn It In will flag this). You need to write your own sentence using the ideas you read. Or even better, synthesize your own ideas and results together with ideas from another source and then cite the source.

This type of synthesis is shown in the example above discussing the Gram stain. Events and results from the laboratory were synthesized together into the same sentence with the idea in the cited source that the decolorization step was too short since all the cells appeared purple.

 

Working with Your Partner

Since you and your partner worked together and will have done the same steps and will have the same results, it may be tempting to share parts of your reports with each other. TurnItIn will recognize the similarities between your reports and flag it as plagiarism.

You must write your own report without sharing text with your partner. However, you are encouraged to get your partner to proofread your report and give feedback and comments to help improve the report before you submit it. The images in your reports may be the same since you will share the same results and will want to choose the best photos for the report.

 

Organization of the Report

The report should be broken into the following sections. Each section should have a bold header with larger font that the text in each section. Do you see how this document is separated into sections with bold headers? This is how your report should look too, except name each section as follows:

• Introduction
• Methods
• Results & Discussion
• Conclusions
• Works Cited
• Activity Log

Example 42.3

Introduction

Introduction text / subsections here.

Methods

Methods subsections and text here.

Results & Discussion

Results and discussion subsections and text here.

Conclusions

Conclusion text here.

Works Cited

Full references here in alphabetical order.

Activity Log

Photos of activity log pages here.

 

Introduction

An introduction gives important background information to the reader. Don't write this report assuming that your instructor knows all of this information already and therefore you shouldn't include it. Instead, write the report as if you were writing it for a biology student who hasn't taken microbiology yet. Therefore, you will need to:

• Address the reasons why identifying bacterial species is important.
• Describe how (generally speaking) identifying bacterial species is done.
• Describe each of the microbiological tests and microbiological approaches that you used in this project including:
  • how each works
  • what each test tells about the bacteria
  • how you determine the results of a test
• Experimental Overview paragraph (see "Important" box below)

 

Example 42.4

For example, if you identified your bacteria as Bacillus subtilis and Escherichia coli, you will have different paragraphs or sub-sections in the Introduction on the following topics:

• Streak plate
• Gram stain
• Starch hydrolysis
• H₂S production
• Oxidase test
• Lactose fermentation

In the paragraph introducing the Gram stain (for example), you will need to discuss:

• How the crystal violet stain will remain inside a thick layer of peptidoglycan
• How the crystal violet stain will be decolorized from a thin layer of peptidoglycan
• How cells with the thin peptidoglycan layer are stained with a different color
• The structure of the cell walls of Gram-positive bacteria
• The structure of the cell walls of Gram-negative bacteria
• The color Gram positive bacteria appear in the microscope after the Gram stain
• The color Gram negative bacteria appear in the microscope after the Gram stain

Important

End the introduction with a paragraph that describes the basic premise and approach of this project and how this approach either resulted in the successful identification of both unknown bacteria, one identification was successful and the other unsuccessful, or that both were not correctly identified. Be sure to name the species you had and what species you identified them as.

It may seem like this is spoiling the ending of the paper - and it is! This is common among scientific publications to end the Introduction with a paragraph that tells the reader what they can expect to read about in the rest of it.

 

Methods

Methods will tell the approaches you used to conduct each test. The Methods section does not discuss the concepts of each test, the meaning of each test, or the results of the tests. The Methods section describes what you did with your bacteria in the laboratory for each test and how you did the tests. The Methods is written in paragraph form (do no bulletpoint or number steps - do not copy from laboratory protocals). Separate the Methods section into subsections.

 

Example 42.5

Continuing the example from above where you identified your bacteria as Bacillus subtilis and Escherichia coli...

Methods

Streak Plate

Text here about what you did to make your streak plates (e.g. using aseptic technique, using a Bunsen burner and loop, where bacteria were collected from [e.g. original Unknown culture, stock TSA slant, etc.], how the petri plate was streaked in quadrants while flaming loop in between, plate inverted and incubated at 37°C for 48 hours).

Gram Stain

Text here about what you did to make bacterial smears and conduct Gram stains.

Starch Hydrolysis Test

Text here about what you did to do the starch hydrolysis test.

H₂S Production Test

Text here about what you did to do the H₂S production test.

Oxidase Test

Text here about what you did to do the oxidase test.

Lactose Fermentation Test

Text here about what you did to do the lactose fermentation test.

 

Since you are only describing how you did a test (the steps you took in the laboratory to do the tests), each subsection in the Methds may be relatively short. The Methods section should not include any results and is not the place to discuss the theory of each test. It should simply state how each test/component was done.

 

Example 42.6

Methods

H₂S Production

To test whether Unknown Bacteria A produces H₂S, Unknown Bacteria A was aseptically transferred from the stock TSA slant into a SIM deep using an inoculation needle. This culture was incubated at 37 °C for 48 hours before it was examined to determine test results.

 

Results & Discussion

Separate the Results & Discussion section into subsections.

 

Example 42.7

Continuing the example from above where you identified your bacteria as Bacillus subtilis and Escherichia coli...

Results & Discussion

Isolation of Unknown Bacterial Species

Text & figures here about streak plate results and discussion

Identification of Unknown Bacterial Species #1

Gram Stain

Text & figures here about Gram stain results and discussion

Starch Hydrolysis Test

Text & figures here about starch hydrolysis results and discussion

Identification of Unknown Bacterial Species #2

H₂S Production Test

Text & figures here about H₂S production test results and discussion

Oxidase Test

Text & figures here about oxidase test results and discussion

Lactose Fermentation Test

Text & figures here about lactose fermentation test results and discussion

Important

Each Results & Discussion subsection should contain both results and discussion:

• Results: simply tells the observation(s) from each test.
• Discussion: interprets observations and the meanings of the results of each test.

Example 42.8

Result for Gram stain Section: "The initial Gram stain showed a mixture of purple-colored cocci arranged in chains and pink-colored bacilli."

Discussion for Gram stain Section: "These results indicate that Unknown Culture #4 contains Gram-positive cocci, possibly Streptococci, and Gram-negative rods. The bacteria staining Gram-positive have a thick layer of peptidoglycan in their cell walls and lack an outer membrane. The Gram-negative bacterial species have cell walls with a thin layer of peptidoglycan and an outer membrane."

 

The Results and the Discussion should be synthesized together in paragraph form in each section.

 

Example 42.9

Example of a Gram Stain subsection of the Results & Discussion:

"After these bacteria were isolated using the quadrant streak-plate technique, the subsequent Gram stains showed one isolate appeared as purple cocci and the other isolate were pink bacilli. There was no evidence of pink bacilli with the purple cocci or purple cocci with the pink rods. This indicates that the two species that were examined in the initial Gram stain were successfully isolated and separated into their own cultures. The purple-staining cocci are a Gram positive bacterial species and will hereafter be referred to as "Unknown Bacteria A." The pink-staining rods are a Gram negative bacterial species and designated as "Unknown Bacteria B" in the remainder of this report."

"Unknown Bacteria A, since they were Gram positive, have cell walls composed of a thick layer of peptidoglycan that adhered to the crystal violet during the Gram stain making it appear purple. These bacterial also would have teichoic acid in their cell walls."

"Unknown Bacteria B, since they were Gram negative, have cell walls composed of a thin layer of peptidoglycan that decolorized when ethanol was added resulting in crystal violet being washed out of the peptidoglycan layer. When these bacteria were subsequently stained with safranin, this results in their pink coloration upon observation. These bacteria also have cell walls with an outer membrane which contains lipopolysaccharide, also known as endotoxin."

 

In the example text above, the description would be further supported with images of the Gram stain of Unknown Bacteria A, and the Gram stain of Unknown Bacteria B. These images will require captions to indicate what the image is. Images can be placed as separate figures, each with their own caption, or arranged together as a single figure with a single caption.

 

This is an example of multiple photos that have been put together as a single figure with one caption:

Figure 1: (A) Gram stain of mixed Unknown Bacterial Culture showing both species mixed together in this culture. (B) Gram stain of isolated unknown bacteria "A." (C) Gram stain of isolated unknown bacteria "B."

 

Conclusions

In the conclusions section of the report, including the following:

• Name the two bacterial species that you identified the species as from the laboratory tests you conducted.
• Tell if the bacterial species identified were in fact the species that you had in the unknown culture. If they were not what was identified, name the correct species.
• If there was a misidentification, tell what species you did have and reflect on and discuss sources of error or events during the project that might have led to misidentification.
• If you successfully identified the bacterial species, reflect on and discuss what likely contributed to your successful identification of the bacterial species.

 

Activity Log

Take clear photos of the activity log or scan these pages and include them in this section of the report.

 

Writing Style

 

Write in Third Person

Write in the third person. This means that you act as a narrator as if you were outside of the experiment and not involved in the experiment.

• First person (don't write this way): I examined my Gram stain and saw that the cells were pink.
• First person (don't write this way): We examined our Gram stain and saw that the cells were pink.
• Second person (don't write this way): When you examined the Gram stain, you saw that the cells were pink.
• Third person (write this way): Upon examining the Gram stain, pink cells were observed.

 

Write in Past Tense

Write in the past tense.

• Future tense (don't write this way): A Gram stain will be done.
• Present tense (don't write this way): A Gram stain is being done.
• Past tense (write this way): A Gram stain was done.

 

Proofread

Use Grammar and Spelling Checkers

Check all of your text for proper grammar and spelling. Make adjustments were necessary.

 

Write Early & Read Multiple Times Before Submitting

Complete your report at least a few days before submitting it. Read it a couple times after writing it (including on separate days). Make edits on each reading.

 

Have a Classmate Proofread and Give Feedback

Complete your report early, print out a copy or email it to a classmate and ask them to read it over and make notes to help you to improve your report. Make edits that you deem will improve your report as suggested by your classmate.

 

Grading

Low Participation Activity Log Deductions

• Reports with activity logs that show 20% less work than your partner will receive a 10% deduction.
• Reports with activity logs that show 40% less work than your partner will receive a 20% deduction.
• Reports with activity logs that show 50%-70% less work than your partner will receive a 50% deduction.
• Reports with activity logs that show 75%-100% less work than your partner will receive an 80% deduction.

 

Grading Rubric

[ChatGPT-generated content]

	Excellent (100%)	Well Done (82%)	Good (70%)	Developing (55%)	Needs Improvement (40%)	Missing/ Unacceptable (0%)
Introduction (40 pts total)
Importance of Identifying Bacterial Species (10 pts)	Clearly explains the importance of bacterial species identification, linking it to real-world applications and the impact on public health, medical treatments, or the environment.	Effectively explains the importance of identification with good detail, and partly addresses some broader applications.	Provides a general explanation of the importance, but lacks detail or real-world context.	Mentions the importance but provides limited or unclear reasoning.	Vague or minimal explanation of the importance.	No explanation or completely off-topic.
Theory of Microbiological Techniques (25 pts)	Thorough explanation of the theory behind each microbiological technique used, emphasizing connections with bacterial biology (enzymes, genes, etc.).	Good explanation of most techniques, with adequate connections with bacterial biology, but lacks some depth.	Adequate explanation of the techniques, but with some gaps in scientific theory or biological features/ implications.	Limited explanation of the theory and biology of techniques.	Poor or incomplete explanation of techniques; lacks connection to biology of bacteria.	No explanation of microbiological techniques or completely incorrect.
Experimental Overview Paragraph (5 pts)	Provides a clear, comprehensive summary of the experimental design, including the procedures and tests used, and how they contribute to the identification of the bacterial species.	Good summary of the experimental design, with a clear outline of procedures and their purpose in the project.	Adequate summary of the experimental design, but lacks some clarity or key procedures.	The experimental overview is unclear, missing important steps or lacking detail on the tests performed.	The overview is vague, incomplete, or poorly structured, making it difficult to understand the experimental process.	No overview provided or completely irrelevant.
Materials and Methods (10 pts total)
Protocol Descriptions (10 pts)	The methods are described in clear, logical, and detailed steps. All laboratory techniques, reagents, supplies are mentioned, and is easy to follow.	The methods are described in a clear and organized manner, with only minor omissions in details about techniques, reagents, or supplies.	The methods are adequately described, but some details are missing or unclear, making it harder to fully understand the procedure.	The methods are partially described, with several missing steps or unclear explanations of key procedures.	The methods are poorly described, lacking clarity, important details, or the correct sequence of steps.	No description of the methods, or the description is entirely incorrect or unrelated to the procedure.
Results and Discussion (40 pts total)
Observations and Results (10 pts)	Results are clearly and accurately described with all observations included. Information is organized and easy to interpret.	Results are described clearly, with most observations included and well-organized, though some details may be missing or unclear.	Results are described, but some important observations are missing or not presented clearly.	Results are incomplete or poorly organized, with key observations missing or difficult to understand.	Results are poorly presented, with major observations missing or unclear.	No results described, or the information is completely incorrect or irrelevant.
Discussion of Implications of the Results (15 pts)	Each result is thoroughly discussed with emphasis on what it indicates about the bacterial species (e.g., enzymes, genetic factors). The discussion connects experimental results to biological principles.	Most results are discussed in detail, with some focus on their biological implications, but the analysis may lack depth or connection to certain biological aspects.	Results are discussed but with minimal detail or clarity regarding their biological implications. Some connections to the biology of the bacteria may be missing.	Results are partially discussed, but biological implications are vague or largely absent. Limited explanation of how the results relate to bacterial biology.	Results are not discussed in relation to bacterial biology, with minimal or no mention of the biological significance.	No discussion of results or biological implications provided.
Progression of Identification Process (5 pt)	The progression of identification is clearly communicated, with each step logically leading to the next.	The progression of identification is clear, but may have minor gaps or lack some detail in explaining how each test contributed to the identification.	The progression of identification is generally clear, but some steps are missing or unclear, lacks detail and/or coherence.	The identification process is confusing or incomplete, with unclear progression between steps or missing tests.	The identification process is poorly explained or disorganized, making it difficult to follow or understand.	No explanation of the identification process is provided, or the process is entirely incorrect.
Figures and Captions (10 pts)	Figures are well-organized and clearly show each test result. Captions are detailed and explain what is shown.	Figures are provided and show most test results clearly. Captions are included but may lack some detail or explanation.	Figures are included but may not be clearly labeled or explained. Captions are brief or unclear.	Figures are poorly organized, incomplete, or not clearly labeled. Captions are minimal or missing.	Figures are poorly presented or absent; captions are vague or entirely missing.	No figures or captions provided.
Conclusion (10 pts total)
Bacterial Species and Evaluation of Correctness (5 pts)	Clearly and confidently identifies the two bacterial species with correct identification based on the results. A clear evaluation of the accuracy of the identifications is provided.	Names the two bacterial species with minor uncertainty. The correctness of the identification is stated.	Names the two bacterial species, but could be stated more clearly and confidently. The correctness of the identification is addressed, but may lack clarity.	Species are named, but unclear about what the species identified were versus the actual species.	Identifies only one or no species, and evaluation if species identified were the same as the actual species addresses one or neither.	No identification of species or completely incoherent. No evaluation whether species are correct is provided.
Factors Contributing to Successful Identification and Misidentification (5 pt)	Clearly identifies multiple factors (test results, methodology, environmental conditions) that contributed to successful identification and any potential misidentification. Demonstrates a comprehensive understanding of the process.	Identifies several factors contributing to correct identification and/or possible misidentification, but may lack some depth or detail.	Identifies a few factors that contributed to the identification or misidentification but misses some key details/ understanding of the process.	Mentions a factor that could have contributed to the identification or misidentification but lacks depth or clarity.	Identifies one or no factors contributing to the identification or misidentification.	No discussion of contributing factors, or completely incorrect.
Works Cited (10 pts total)
Citation Consistency, Formatting, and Source Quality (10 pts)	At least 3 professional sources are used and cited consistently throughout the paper. Citation and reference formats are professional, consistent, and complete with no errors.	At least 3 professional sources are used and cited consistently throughout the paper. Citation and reference formats are mostly professional, with minor inconsistencies or errors.	At least 3 professional sources are used, but citation and reference formatting has noticeable inconsistencies or errors.	Fewer than 3 professional sources are used, or citation format is inconsistent or incomplete.	Sources are incomplete or improperly formatted, or fewer than 3 professional sources are used.	No citations or completely incorrect citation formatting.
Report Quality (50 pts total)
Organization and Writing Quality (15 pts)	Writing is clear, concise, and highly organized; no grammatical or spelling errors.	Well-organized and clear writing with minimal grammatical or spelling issues.	Generally clear writing, but with several grammatical or spelling errors that detract from readability.	Writing lacks clarity or has frequent grammatical or spelling errors.	Writing is difficult to follow due to numerous grammatical or spelling errors.	Writing is incoherent or extremely difficult to understand.
Adherence to Guidelines (10 pts)	Fully follows all guidelines; report is well-structured and meets all requirements.	Follows most guidelines; minor deviations or omissions.	Adequately follows guidelines but with some notable omissions or deviations.	Does not fully follow guidelines; significant omissions or structural issues.	Lacks adherence to guidelines; many structural or content issues.	Completely ignores guidelines.
Overall Quality (15 pts)	The report is exceptionally well-done, clear, and professional in presentation.	The report is well-written and professional with minimal errors.	The report is adequate, but there are several issues with clarity or organization.	The report is incomplete or lacks clarity in several areas.	The report is poorly written or lacks essential content.	The report is unacceptable or not submitted.

 

OpenAI. (2025). Microbiology Class Assistant [ChatGPT-generated content]. Retrieved March 5-6, 2025.

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