Recognizing possible contamination
By the end of this lesson
- Describe visible changes before assigning causes
- Distinguish suspicion from confirmed identification
- Protect other cultures while investigating patterns
See it
Contamination may appear as colonies, cloudiness, films, unusual growth, odors after opening in appropriate settings, or changes in plant performance, but not every abnormal appearance proves a specific organism. Visual inspection is useful, yet some contaminants can be latent or difficult to detect.
Understand it
Describe visible changes before assigning causes
Describe what is visible before naming a suspected organism.
Describe what is seen first; visual appearance alone does not establish a contaminant's species or source.
Distinguish suspicion from confirmed identification
Isolate suspect cultures according to the lab's appropriate procedure.
Protect unaffected work while keeping suspect cultures traceable under the lab's appropriate procedure.
Protect other cultures while investigating patterns
A repeated pattern should trigger investigation of source and workflow.
An observation can support suspicion while retaining uncertainty about identification and spread.
Worked example
A jar has cloudiness and an unusual film. Record those visible findings and flag possible contamination. A photograph alone does not establish the organism’s species, and unaffected cultures should be protected according to the lab’s procedure.
Explain your decision before opening the worked reasoning below.
Show the worked reasoning
Visible inspection has limits; absence of an obvious sign is not proof that no contamination exists.
Repeated patterns justify investigation, but a pattern alone does not identify the organism or exact entry pathway.
Do not identify a contaminant species solely from a casual visual impression.
Try it
What should the example's first note say?
Use the worked example above to explain your answer in your own words before taking the quiz.
Lesson quiz
Assessment version: 2026-10-15-v2. Previous reading-completion markers are retained. This revised quiz has its own result.
Apply it
Use the worked example to write a short decision record: what did you observe, which rule did you apply, and what would you check before acting?
Completion marks reading progress, not a quiz pass or professional certification.