Edexcel A Level (IAL) Biology -6.1 Culturing Microorganisms- Study Notes- New Syllabus
Edexcel A Level (IAL) Biology -6.1 Culturing Microorganisms- Study Notes- New syllabus
Edexcel A Level (IAL) Biology -6.1 Culturing Microorganisms- Study Notes -Edexcel A level Biology – per latest Syllabus.
Key Concepts:
- 6.1 understand the principles and techniques involved in culturing microorganisms, using aseptic technique
Principles and Techniques of Culturing Microorganisms
🌱 Introduction
Microorganisms can be grown in the lab to study their behaviour, growth rate or response to antibiotics. To do this safely and without contamination, we use aseptic techniques and proper culturing methods.
🔬 Key Ideas You Must Know
1. What is culturing?
- Growing microorganisms under controlled conditions.
- Usually done on nutrient agar or in nutrient broth.
2. Why aseptic technique is important?
- Prevents unwanted microbes entering the culture.
- Protects you from potential pathogens.
- Ensures results are reliable and not affected by contamination.
🧪 Aseptic Technique: Core Principles
- Work close to a flame
Heat produces an updraft which carries microbes away. - Sterilise equipment before and after use
Use a Bunsen burner to heat loops until red-hot. - Minimise exposure time
Keep petri dish lids slightly open only when needed. - Disinfect work surfaces
Before starting and after finishing. - Wash hands and wear protective gear
Gloves, lab coat, tied hair, no loose sleeves.
🧫 How to Culture Microorganisms (Step-by-Step)
1. Prepare nutrient medium
- Nutrient agar or broth provides food for microbes.
- Heat to sterilise if required.
2. Sterilise all tools
- Inoculating loop
- Glassware
- Petri dishes (usually pre-sterilised)
3. Inoculate the medium
- Sterilise loop → cool it briefly
- Dip into the bacterial sample
- Streak gently across the agar surface in a zig-zag pattern
- Keep lid as close as possible to prevent airborne microbes entering
4. Seal and incubate
- Seal dish with tape (NOT fully closed to avoid anaerobic growth).
- Incubate at 25°C for school labs
- This temperature slows growth of harmful human pathogens.
5. Observe colonies
- After 1–2 days, look for colony shape, size and number.
- Do NOT open plates after incubation.
📋 Summary Table
| Concept | Short Reminder |
|---|---|
| Aseptic technique | Prevent contamination + ensure safe handling |
| Sterilisation | Flame loop till red, disinfect surfaces |
| Exposure time | Keep lids closed as much as possible |
| Inoculation | Use sterile loop to streak microbes |
| Incubation | 25°C in school labs, taped loosely |
| Observation | Look at colonies without reopening |
📌 Quick Recap
Grow microbes on agar/broth.
Use aseptic technique to avoid contamination.
Flame → Cool → Streak is the basic inoculation process.
Incubate at 25°C, tape two sides.