Record Keeping and Formal Written Communication for Microbiological Study
Welcome to this guide on record keeping and scientific reporting for A2 6: Microbiology! Whether you are tracking bacterial growth in the lab or writing up your portfolio, keeping clear, accurate records is one of the most vital skills of a professional microbiologist. In the pharmaceutical and healthcare industries, poor records can lead to contaminated medicines or misdiagnoses. By mastering these conventions now, you will not only gain top marks in your CCEA portfolio but also learn how real scientists ensure that their work is safe, reliable, and reproducible.
Don't worry if the rules seem strict at first. Once you break them down step-by-step, they become second nature!
---1. Laboratory Notebook Conventions & Standard Operating Procedures (SOPs)
What is a Standard Operating Procedure (SOP)?
A Standard Operating Procedure (SOP) is a detailed, step-by-step written instruction that describes how to perform a routine laboratory activity. Following an SOP ensures that every scientist in the lab carries out a procedure in the exact same way, guaranteeing consistent results and maximum safety.
In microbiology, SOPs are essential for aseptic techniques. Key SOP standards include:
• Autoclaving (Sterilization): Culture media, glassware, and hazardous waste must be sterilized in an autoclave. The standard setting is \(121^\circ\text{C}\) for \(15\text{ minutes}\) at \(15\text{ psi}\) (pounds per square inch of pressure). This combination of high heat and pressure kills all vegetative cells and resistant bacterial endospores.
• The "No-Touch" Technique: Never touch sterile surfaces, pipettes, loops, or the rims of sterile bottles with your fingers or unsterilized tools. This prevents accidental contamination of your cultures and the surrounding work environment.
Lab Book Rules: Maintaining an Industrial Audit Trail
In commercial laboratories and hospital testing facilities, lab books are legal documents. If a batch of antibiotics is contaminated, regulators look at the lab book to see what happened. This is called an audit trail.
To maintain a proper audit trail in your A2 6 portfolio, follow these golden rules:
• Contemporaneous Recording: Notes must be written at the time of the experiment, not remembered and written up days later.
• Dating and Signing: Every single page and entry must be clearly dated and signed by you.
• Correcting Mistakes: Never use correction fluid (Tipp-Ex/white-out) or scribble over an error. If you make a mistake, draw a single neat line through it and write the correction beside it. The original entry must remain readable so that anyone auditing your work knows nothing was hidden.
• Include Raw Data: Always keep your original, "messy" laboratory notes and raw counts. Examiners require raw data alongside clean tables as proof of authenticity.
Key Takeaway: Lab records must be contemporaneous, dated, signed, and corrected only with a single line. SOPs like autoclaving at \(121^\circ\text{C}\) for \(15\text{ minutes}\) at \(15\text{ psi}\) protect experimental validity and safety.
---2. Data Presentation Standards
Table Construction
When presenting microbial data in tables:
• Give the table a clear, informative title.
• Place physical quantities and units in the column headings only, using a solidus (forward slash). For example, write Time / hours or Zone of inhibition / mm. Do not repeat units in the body of the table.
• Record all raw measurements to the same degree of precision (same number of decimal places).
Expressing Microbial Counts
Bacterial populations grow rapidly into the millions. Writing out long strings of zeros is impractical and prone to counting errors. Microbiologists express cell numbers and Colony-Forming Units (CFU) using scientific notation.
For example, if a plate count yields \(3,500,000\text{ CFU per millilitre}\), record this as:
\(3.5 \times 10^6\text{ CFU/ml}\)
Graphing Standards
When transforming table data into graphs for your portfolio:
• Scale: Scales must be linear and span enough of the graph paper so that your data points occupy at least \(50\%\) of the grid in both directions.
• Axes: Independent variable on the x-axis, dependent variable on the y-axis, with full labels and units matching your table headers.
• Error Bars: If you have carried out repeat measurements (e.g., three replicates for each antibiotic concentration), calculate the mean and plot error bars to show the range or standard deviation of your data. Error bars demonstrate reliability and experimental variability.
Key Takeaway: Units belong strictly in table headers, microbial counts must use scientific notation (e.g., \(3.5 \times 10^6\text{ CFU/ml}\)), and graph scales must cover at least \(50\%\) of the grid with error bars plotted for repeats.
---3. Formal Scientific Report Format
CCEA requires your formal written communication in Unit A2 6 to follow the structure of a published peer-reviewed scientific paper. Here is the breakdown of each mandatory section:
1. Title
Must be descriptive, precise, and state both the independent and dependent variables (e.g., "An investigation into the effect of tea tree oil concentration on the growth of Escherichia coli in nutrient broth").
2. Abstract
A concise summary of the entire study, typically between \(150\) and \(250\text{ words}\). It must briefly outline the aim, the method, the key quantitative results, and the main conclusion. It is written last, once the experiment and analysis are complete.
3. Introduction
Provides the biological context and theoretical background. Here you explain the underlying science, relevant metabolic pathways, or antimicrobial mechanisms, and state your research hypothesis.
Crucial Naming Rule (Binomial Nomenclature):
Whenever you name a microorganism, you must use the standard binomial system:
• The Genus starts with a capital letter, and the species starts with a lowercase letter.
• When typed, the name must be in italics (e.g., Escherichia coli or Staphylococcus aureus).
• When handwritten in your lab book, underline the name (e.g., Escherichia coli).
• After writing the full name once, you may abbreviate the genus to its initial (e.g., E. coli or S. aureus).
4. Risk Assessment
Microbiology involves working with live biological agents. Your risk assessment must clearly identify:
• Hazards: The agent or equipment causing potential harm (e.g., biohazard: bacterial culture; flame: Bunsen burner).
• Risks: How the hazard could cause harm (e.g., accidental ingestion or skin contamination leading to infection; burns from open flame).
• Control Measures: Specific steps taken to reduce risk (e.g., disinfect benches with Virkon before and after, work within \(20\text{ cm}\) of a blue Bunsen flame, incubate plates at \(25^\circ\text{C}\)).
5. Method
The method must be written in the past tense using the passive voice (e.g., write "The agar was inoculated using a sterile spreader..." rather than "I inoculated the agar...").
It must contain precise quantitative details so that another scientist could replicate your study exactly. Always state:
• The specific incubation temperature: in school laboratories, cultures are incubated at \(25^\circ\text{C}\) (never \(37^\circ\text{C}\), as this promotes the growth of human pathogens).
• The exact duration of incubation (e.g., \(24\) to \(48\text{ hours}\)).
6. Results
Present your processed data in clear tables and graphs. This section must also contain appropriate statistical analysis (such as Student's t-tests to compare two means, or correlation coefficients to assess relationships) to evaluate whether your observed differences are statistically significant.
7. Discussion and Conclusion
Interpret what your results mean in relation to your original aim and hypothesis. You must compare your findings with published values or theoretical expectations from textbooks and scientific literature. Highlight any anomalies, discuss experimental limitations, and suggest valid improvements.
Key Takeaway: A formal report requires a past-tense passive method, binomial names formatted correctly (Genus species), a risk assessment identifying biohazards and controls, and a \(150\)–\(250\text{ word}\) abstract summarizing the entire investigation.
---4. Common Pitfalls & How to Avoid Them
Examiners regularly report that students lose easy marks on the following details. Keep these in mind when preparing your portfolio:
• Confusing the Abstract and Introduction:
An Introduction sets the scene with background theory and does not contain results. An Abstract is a mini-summary of the entire paper and must include your final results and conclusion.
• Binomial Formatting Errors:
Writing "escherichia Coli", "E. Coli", or failing to italicize/underline is a common error. Always use Escherichia coli or E. coli.
• Vague Incubation Details:
Never simply write "the plates were incubated". Always state the exact temperature (\(25^\circ\text{C}\)) and time (e.g., \(48\text{ hours}\)).
• Discarding Raw Data:
Do not throw away your original tally charts or messy rough notes! Mount them neatly in your portfolio alongside your finalized computer-generated tables.
Quick Revision Checklist
Before submitting your A2 6 microbiology portfolio, verify that you have:
• Documented SOPs including autoclave conditions: \(121^\circ\text{C}\) for \(15\text{ minutes}\) at \(15\text{ psi}\).
• Followed the no-touch technique throughout.
• Crossed out lab book mistakes with a single line (no Tipp-Ex) and kept raw data.
• Formatted microbial counts in scientific notation (e.g., \(3.5 \times 10^6\text{ CFU/ml}\)).
• Drawn graphs with linear scales occupying \(\ge 50\%\) of the grid and included error bars.
• Formatted binomial names correctly in italics with a capitalised Genus.
• Written the method in the past tense, passive voice specifying incubation at \(25^\circ\text{C}\).
• Included an abstract of \(150\)–\(250\text{ words}\) covering aim, method, results, and conclusion.